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CIRCUMFERENTIAL ACOUSTICSCANNING TOOL

(CAST-V)

SERVICE MANUAL

July 1997

Revision NW

Manual No. 770.00696



Notices

All information contained in this publication is confidential and proprietary property of

Halliburton Energy Services, Inc. Any reproduction or use of these instructions,

drawings, or photographs without the express written permission of an officer of

Halliburton Energy Services, Inc. is forbidden.

© Copyright 1997 Halliburton Energy Services, Inc.

All Rights Reserved.

Printed in the United States of America

The drawings in this manual were the most recent revisions and the best quality availableat the time this manual was printed. We recommend that you check your manual for

individual drawing clarity and revision level. Should you have equipment with revisions

later than the drawings in this manual, or should you require higher quality drawings

than the drawings in this manual, order replacements from the Engineering Print Room

in Houston.



07/97 770.00696-NW Revision Record

Revisions

Revision Record

Circumferential Acoustic Scanning Tool (CAST-V)

Service Manual

Date Description

07/97 Initial manual release (NW).



HALLIBURTON ENERGY SERVICES Manual No. 770.00696

Technical Communications - Houston Circumferential Acoustic Scanning Tool

P.O. Box 42800 (CAST-V)

Houston, Texas 77242-8034 Service Manual

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02/99 770.00696-NW Table of Contents i

Contents

Table of Contents

General Information...............................................................................1-1

Introduction............................................................................................................................................... 1-1Equipment Description ............................................................................................................................. 1-2

Top Assembly Drawings .................................................................................................................... 1-2

Major Assembly Drawings................................................................................................................. 1-2

Equipment List ................................................................................................................................... 1-4

Specifications ............................................................................................................................................ 1-5

Mechanical.......................................................................................................................................... 1-5

Electrical............................................................................................................................................. 1-5

Measurement ...................................................................................................................................... 1-5

Image Mode ................................................................................................................................. 1-5

Cased-Hole Mode ........................................................................................................................ 1-6

Safety......................................................................................................................................................... 1-6

Personal Safety................................................................................................................................... 1-6

Equipment Safety ............................................................................................................................... 1-6

Theory of Operation...............................................................................2-1

Introduction............................................................................................................................................... 2-1

Nature of the Measurement....................................................................................................................... 2-1

Physical Principles.............................................................................................................................. 2-1

Acoustic Waveforms .......................................................................................................................... 2-4

Tool Processing: Window Sum and Thickness .................................................................................. 2-5

Transit Time Calculations .................................................................................................................. 2-6

Acoustic Impedance ........................................................................................................................... 2-7

Directional Measurements.................................................................................................................. 2-7

Functional Description......................................................................................................... ................... 2-10

System Functions.............................................................................................................................. 2-10

Automatic Gain Control............................................................................................................. 2-10

Outputs: Scan Data Formats ...................................................................................................... 2-11

Slow Channel Data Acquisition................................................................................................. 2-12



ii Table of Contents 770.00696-NW 02/99

Inputs: Tool Commands............................................................................................................. 2-12

Scanner Assembly ( Drawing 707.55531)........................................................................................ 2-13

Description ................................................................................................................................. 2-13

Block Diagram ........................................................................................................................... 2-15

Transducers................................................................................................................................ 2-16

Directional Sub (Drawing 707.55572) ............................................................................................. 2-17

Description ................................................................................................................................. 2-17

Block Diagram ........................................................................................................................... 2-18Electronics Cartridge (Drawing 707.55598) .................................................................................... 2-19

Description ................................................................................................................................. 2-19

Block Diagram ........................................................................................................................... 2-19

Circuit Descriptions ................................................................................................................................ 2-23

Remote Telemetry Unit RTU-B (Drawing 3.85601) ....................................................................... 2-23

V40 CPU Board (Drawing 707.55666) ............................................................................................ 2-24

Commutator Board (Drawing 707.55559) ....................................................................................... 2-26

Circuit Description............................................................................................................ ......... 2-26

Compass Board (Drawing 707.55574) ............................................................................................. 2-28

Power.......................................................................................................................................... 2-28

Saturable Inductor...................................................................................................................... 2-28Circuitry ..................................................................................................................................... 2-30

Oscillator-Driver.............................................................................................................. .... 2-30

Sense Amplifiers ................................................................................................................. 2-30

Measurement Calculations......................................................................................................... 2-32

Factory Adjusts .......................................................................................................................... 2-32

Data Acquisition Board (Drawing 707.41002) ................................................................................ 2-33

Gain Control............................................................................................................................... 2-33

Reference Voltage.............................................................................................................. ........ 2-34

ADC ........................................................................................................................................... 2-34

Preamplifier/Fire Board (Drawing 707.55668) ................................................................................ 2-34

Generation Of The Ultrasonic Pulse .......................................................................................... 2-35

Recovering the Return Signal .................................................................................................... 2-36

Auxiliary Circuitry............................................................................................................ ......... 2-39

CAST-V Power Circuitry ................................................................................................................. 2-39


Instrument Power................................................................................................................. 2-40

Startup.................................................................................................................................. 2-42

Inverter ................................................................................................................................ 2-42

Preregulator ......................................................................................................................... 2-43

400-Vdc Circuitry................................................................................................................ 2-43

Motor Voltage............................................................................................................................ 2-44

R-to-D Board (Drawing 707.55561) ................................................................................................ 2-44

Circuit Description............................................................................................................ ......... 2-44Slow ADC Board (707.55587) ......................................................................................................... 2-47


Analog Circuitry.................................................................................................................. 2-48

Reference Voltage ............................................................................................................... 2-48

Negative 5-Vdc.................................................................................................................... 2-48

Input Selector....................................................................................................................... 2-48

Buffer................................................................................................................................... 2-49

Digital Circuitry ......................................................................................................................... 2-49



02/99 770.00696-NW Table of Contents iii

Strobe................................................................................................................................... 2-49

Counters............................................................................................................................... 2-49

EPLD ................................................................................................................................... 2-50

Internal Calibration.............................................................................................................. 2-51

RS-232 Data Output................................................................................................................... 2-51

Data Output.......................................................................................................................... 2-51

Output Waveform................................................................................................................ 2-52

Disassembly and Assembly..................................................................3-1

Introduction............................................................................................................................................... 3-1

Tools And Equipment Required ............................................................................................................... 3-1

Basic DITS Disassembly .......................................................................................................................... 3-2

Electronics and Directional Sub ......................................................................................................... 3-2

Basic DITS Assembly............................................................................................................................... 3-4

Electronics and Directional Sub ......................................................................................................... 3-4

Disassembly of the Cast-V Scanner.......................................................................................................... 3-5Reference Drawings ........................................................................................................................... 3-5

Oil Drain............................................................................................................................................. 3-5

Transducer Holder Removal...................................................................................................... ......... 3-5

Face Seal Removal ............................................................................................................................. 3-6

Housing Disassembly ......................................................................................................................... 3-6

Mud-Cell Removal ............................................................................................................................. 3-6

Motor Assembly Removal.................................................................................................................. 3-6

Slip-Ring Removal ............................................................................................................................. 3-6

Shaft and Bearing Removal................................................................................................................ 3-7

Assembly of the Cast-V Scanner .............................................................................................................. 3-7

Motor-Resolver Assembly........................................................................................................ .......... 3-7

Motor Mount Assembly ..................................................................................................................... 3-8

Shaft Assembly................................................................................................................................... 3-8

Slip-Ring Installation......................................................................................................... ................. 3-8

Face Seal Installation......................................................................................................... ................. 3-9

Keyed Sub and Motor Housing Assembly ....................................................................................... 3-10

Mud-Cell Assembly.......................................................................................................................... 3-10

Pressure Balance Assembly...................................................................................................... ........ 3-11

Motor Assembly and Keyed Housing Assembly ............................................................................. 3-12

DITS Upper Sub Assembly ........................................................................................................ ...... 3-12

Holder and Transducer Assembly .................................................................................................... 3-13

Oil-Fill Procedure ................................................................................................................................... 3-13

Pressure and Temperature Test ............................................................................................................... 3-14

Adjustment of the Motor/Resolver Assembly ........................................................................................ 3-15

Equipment Required......................................................................................................................... 3-15

Reference Drawings ......................................................................................................................... 3-15

Procedure.......................................................................................................................................... 3-15

Fixed Position Alignment .......................................................................................................... 3-17



iv Table of Contents 770.00696-NW 02/99

Electrical Zero Alignment.......................................................................................................... 3-18

Calibration and Verification ..................................................................4-1

Introduction............................................................................................................................................... 4-1

Calibration of the Directional Sub ............................................................................................................ 4-1

General................................................................................................................................................ 4-1Equipment........................................................................................................................................... 4-2

Magnetometer Adjustment ........................................................................................................ ......... 4-2

Adjustment Procedure........................................................................................................... ....... 4-5

Recheck of Magnetometer Adjustment ....................................................................................... 4-8

Inclinometer Adjustment........................................................................................................ ............ 4-9

Adjustment Procedure........................................................................................................... ....... 4-9

Quality Control Data Collection (And Temperature Testing)............................................................ 4-9

Page 1, Data Sheet Instructions ................................................................................................... 4-9

Page 2, Data Sheet Instructions ................................................................................................... 4-9

Directional Sub Check ............................................................................................................................ 4-14

Test Stand Setup............................................................................................................................... 4-14Installing The Directional Sub Chassis...................................................................................... 4-15

Magnetometer Check........................................................................................................................ 4-15

Inclinometer Check .......................................................................................................................... 4-16

Troubleshooting.....................................................................................5-1

Introduction............................................................................................................................................... 5-1

Required Equipment ................................................................................................................................. 5-1

CAST-V Testing ....................................................................................................................................... 5-2

Resistance Tests.................................................................................................................................. 5-2

Power Supply (Drawing 707.50606).................................................................................................. 5-3

Setup Procedure ........................................................................................................................... 5-4

Power Supply Adjustment ........................................................................................................... 5-5

Parallel/Serial RTU-B Board (Drawing 3.85601) .............................................................................. 5-6

Setup Procedure ........................................................................................................................... 5-6

Troubleshooting ........................................................................................................................... 5-6

R-to-D Board (Drawing 707.55561) .................................................................................................. 5-7

Setup Procedure ........................................................................................................................... 5-7

Troubleshooting ........................................................................................................................... 5-7

Commutator Board (Drawing707.55559) .......................................................................................... 5-7

Setup Procedure ........................................................................................................................... 5-8

Troubleshooting ........................................................................................................................... 5-9V40 CPU Board (Drawing 707.55666) .............................................................................................. 5-9

Setup Procedure ........................................................................................................................... 5-9

Slow ADC Board (Drawing 707.55587) .......................................................................................... 5-10

Setup Procedure ......................................................................................................................... 5-10

Troubleshooting ......................................................................................................................... 5-11

Preamplifier/Fire Board (707.55668) ............................................................................................... 5-11

Setup Procedure ......................................................................................................................... 5-12




02/99 770.00696-NW Table of Contents v

Data Acquisition Board (Drawing 707.41002) ................................................................................ 5-14

Setup Procedure ......................................................................................................................... 5-14


Acquisition Control and DSP Board (Drawing 707.55665)............................................................. 5-15

Setup Procedure ......................................................................................................................... 5-15

Gain-Range Testing.......................................................................................................................... 5-16

Test Procedure............................................................................................................................ 5-16

Heat Test and QC Data Collection ................................................................................................... 5-19Procedure ................................................................................................................................... 5-19

References .............................................................................................6-1

Introduction............................................................................................................................................... 6-1

Manuals..................................................................................................................................................... 6-1

DITS CAST Tool Upgrade to the CAST-V.............................................................................................. 6-1

Reference Drawings ........................................................................................................................... 6-1

General Information ........................................................................................................................... 6-2

Transformer Identification ................................................................................................................. 6-2Upgrade Procedure ............................................................................................................................. 6-2

Resistance Measurements ................................................................... A-1

Introduction...............................................................................................................................................A-1

Downhole End Resistance Measurements ................................................................................................A-1

Uphole End Resistance Measurements.....................................................................................................A-3

CAST-V PC Monitor Program ............................................................... B-1

Introduction...............................................................................................................................................B-1

Required Equipment .................................................................................................................................B-1

Operation...................................................................................................................................................B-1



vi Table of Contents 770.00696-NW 02/99

This page is intentionally left blank.



02/99 770.00696-NW List of Figures vii

Figures

List of Figures

Figure 1-1: CAST-V Tool......................................................................................................................... 1-3

Figure 2-1: Transducer Model .................................................................................................................. 2-2

Figure 2-2: Pressure Waves 14 µs After Firing........................................................................................ 2-2




Figure 2-6: Voltage Waveform, Open Hole........................................................................................ ...... 2-5

Figure 2-7: Voltage Waveform, Cased Hole ............................................................................................ 2-5

Figure 2-8: Azimuth and Relative-Bearing Diagram................................................................................ 2-8

Figure 2-9: Cased-Hole Waveform......................................................................................................... 2-10

Figure 2-10: CAST-V Scanner................................................................................................................ 2-14

Figure 2-11: CAST-V Scanner Block Diagram...................................................................................... 2-15

Figure 2-12: CAST-V Transducer .......................................................................................................... 2-16

Figure 2-13: CAST-V Directional Sub ................................................................................................... 2-17

Figure 2-14: Directional Sub Block Diagram..................................................................................... .... 2-18

Figure 2-15: Electronics Block Diagram ................................................................................................ 2-19

Figure 2-16: DSP Block Diagram........................................................................................................... 2-20

Figure 2-17: V40 Telemetry CPU Block Diagram ................................................................................. 2-21

Figure 2-18: Waveforms from a Commutator Board ............................................................................. 2-27

Figure 2-19: Saturable Reactor Flux Diagram......................................................................................... 2-28

Figure 2-20: Analog Waveforms from a Compass Board........................................................................ 2-29

Figure 2-21: Gate Timing versus Saturation Curve.................................................................................. 2-31

Figure 2-22: Fire-Pulse............................................................................................................................ 2-36



viii List of Figures 770.00696-NW 02/99

Figure 2-23: Gain and Frequency Response Curves ................................................................................ 2-38

Figure 2-24: CAST-V Power Circuitry Block Diagram ......................................................................... 2-41

Figure 2-25: Waveforms from the Oscillator and Resolver Transformer .............................................. 2-45

Figure 2-26: Amplitude Modulation Resulting from Rotation of the Scanner ......................................... 2-46

Figure 2-27: Timing Relationships of STROBE, CAL, and HOLDNOT............................................... 2-50

Figure 2-28: Timing Relationships of STROBE, CAL, and RS-232 Output............................................ 2-53

Figure 3-1: Removing the DITS Connector from the Pressure Housing.................................................. 3-3

Figure 3-2: Installing the DITS Connector into the Housing ................................................................... 3-4

Figure 3-3: Piston Seals........................................................................................................................... 3-12

Figure 3-4: Piston Gage Position ............................................................................................................ 3-14

Figure 3-5: Setup Connections for Resolver Adjustment with the CAST Tool ..................................... 3-16

Figure 3-6: Setup Connections for Resolver Adjustment with the Simulator Board ............................. 3-16

Figure 3-7: Relationship of the Keyway to the Orientation Hole at Electrical Zero.............................. 3-17

Figure 3-8: Run Connections for the Motor with the CAST Tool.......................................................... 3-18

Figure 3-9: Run Connections for the Resolver Setup with the Simulator Board ................................... 3-19

Figure 4-1: Test Stand Setup................................................................................................... .................. 4-3

Figure 4-2: Test Setup Wiring .................................................................................................................. 4-4

Figure 4-3: Gate Timing Relationships on the Compass Board ............................................................... 4-6

Figure 4-4: Signal Waveforms on the Compass Board. ........................................................................... 4-7

Figure 4-5: Vertical Stand Position......................................................................................................... 4-14

Figure 4-6: Stand Position for 90-Degree Inclination ............................................................................ 4-16

Figure 4-7: Stand Position for 5-Degree Inclination .............................................................................. 4-17

Figure 5-1: Bench Test Wiring Diagram .................................................................................................. 5-2

Figure 5-2: Block Diagram of the Cast-V Power Supply ......................................................................... 5-3

Figure 5-3: Load Resistances for Power Supply Testing.......................................................................... 5-4

Figure 5-4: Waveforms from Commutator Board FET Drains ................................................................ 5-8

Figure 5-5: Stand Test Target Setup (distances in in.) ........................................................................... 5-12

Figure 5-6: Fire-Pulse Waveform ................................................................................................ ........... 5-13

Figure 5-7: Gain Test Setup .................................................................................................................... 5-17

Figure 5-8: Oven Test Setup ................................................................................................................... 5-21



02/99 770.00696-NW List of Figures ix

Figure 6-1: Toroid Winding...................................................................................................................... 6-3

Figure 6-2: Wiring of Modified Transformer ........................................................................................... 6-4

Figure B-1: PC Monitor Program Main Menu ....................................................................................... ..B-2

Figure B-2: Waveform Data for Openhole Mode.....................................................................................B-3

Figure B-3: Waveform Data for Cased-Hole Mode .................................................................................B-6

Figure B-4: Scan Data for Openhole Mode ........................................................................................ ......B-7

Figure B-5: Scan Data For Cased-Hole Mode...................................................................................... ....B-8



x List of Figures 770.00696-NW 02/99

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06/96 770.00696-NW List of Tables xi

Tables

List of Tables

Table 1-1: CAST-V Tool Primary Components ...................................................................................... . 1-4

Table 1-2: Additional Equipment ............................................................................................................. 1-4

Table 2-1: Tool Data Scan Format............................................................................................... ........... 2-11

Table 2-2: Slow Channel Auxiliary Data................................................................................................ 2-12

Table 2-3: Input Select and First-Stage Gain Control ............................................................................ 2-37

Table 2-4: Second-Stage Gain Control ................................................................................................... 2-37

Table 2-5: CAST-V Power Conductor-to-Pin Identification.................................................................. 2-39

Table 2-6: Sequence of Bits Transmitted................................................................................................ 2-51

Table 5-1: Parameters in the V40 CPU Slow-Channel Data Processing................................................ 5-10Table 5-2: Slow ADC Voltage Reference............................................................................................... 5-11

Table 5-3: Gain Test, Increasing Attenuation and Decreasing Amplitude............................................. 5-17

Table 5-4: Gain Test, Decreasing Attenuation and Increasing Amplitude............................................. 5-18

Table 5-5: Gain Test, Mud-Cell Channel......................................................................................... ....... 5-18

Table A-1: Downhole End Resistance Measurements..............................................................................A-1

Table A-2: Uphole End Resistance Measurements ..................................................................................A-3

Table B-1: Tool Commands of the CAST-V PC Monitor Program .........................................................B-1

Table B-2: Tool Parameters of the CAST-V PC Monitor Program..........................................................B-4



Halliburton Energy Services

07/97 770.00696-NW General Information 1-1

General Information

IntroductionThis technical manual provides the theory of operation and maintenance for the

Circumferential Acoustic Scanning Tool (CAST-V). Study the manual closely to

develop a thorough understanding of the tool before operating or servicing the tool for

the first time. Observe all precautionary notes to minimize the risk of personal injury or

damage to equipment.

Tabbed sheets physically divide the manual into six sections and two Appendices.

Section 1, General Information, discusses the scope and arrangement of the manual,

describes the tool and explains its purpose, lists equipment specifications, and provides

safety information.

Section 2, Theory of Operation, presents the principles of operation of the CAST-V. A

functional description of the hardware accompanied by block diagrams and detailed

circuit descriptions is included.

Section 3, Disassembly and Assembly, contains step-by-step disassembly and assembly

procedures for the CAST-V. A list of tools and equipment required to disassemble and

assemble the CAST-V is provided.

Section 4, Calibration and Verification, contains both hardware and software procedures

for the CAST-V. A list of tools and equipment required to perform shop and field

calibration or verification of the CAST-V is provided.

Section 5, Troubleshooting, contains a series of circuit checks complete with

corresponding values (voltage, resistance, and others). These checks are provided to help

isolate electrical and electronic faults to a repairable level. A list of test equipment and

the appropriate setup is provided.

Section 6, References, contains material that may be helpful during operation,

maintenance, and troubleshooting of the CAST-V.

Appendix A, Resistance Measurements, contains resistance values for the uphole and

downhole ends for the CAST-V Electronics Chassis.

Appendix B, CAST-V PC Monitor Program, contains information for sending tool

commands and monitoring tool data without a surface system. A list of equipment is

provided.

Section

1



1-2 General Information 770.00696-NW 07/97

Equipment DescriptionThe Circumferential Acoustic Scanning Tool (Figure 1-1) is an ultrasonic tool designed

to provide high-resolution images in both cased and open boreholes. The tool contains a

high-frequency acoustic transducer that rotates in an interchangeable head at the bottom

of the tool. A second acoustic transducer is mounted in the scanner housing and is used

to measure characteristics of the borehole fluid. A directional sub is provided to orient

images to either the high side of the hole or to north. Images consist of 200 points

horizontally by 40 samples per foot vertically in the image mode and 100 points by 4

samples per foot in the cased-hole mode. The CAST-V is a DITS tool designed to

operate on multiconductor cables in trucks with the EXCELL 2000 series surface

systems.

In both cased-hole and image modes, the system can provide high-resolution images

indicating texture changes in the borehole wall or casing. Images provided by the higher

resolution image mode can be used to identify fractures or to find defects in casing. The

cased-hole mode is used primarily to determine cement bonding and to image channels

in the cement directly behind the casing. Images can be oriented to either the tool body

or the high side of the hole in any operating mode. Open-hole images can be oriented to

north using an internal compass.

The CAST-V tool must be run centralized in fluid-filled boreholes. It must be the bottom

tool in any combination. Its operation is limited by factors such as high mud density and

dissolved gasses that increase the attenuation of the tool’s acoustic pulses as they travel

through the borehole fluid.

Top Assembly Drawings

The CAST-V top assembly drawing number is 707.55600.

The DITS CAST tool upgrade to CAST-V is 707.55650

Major Assembly Drawings

The CAST-V major assemblies and their drawing numbers are listed below. Tables 1-1

and 1-2 show the primary components, additional equipment, and part numbers.

• Electronics Assembly (Instrument Section), 707.55598

• Electronics Assembly (DITS CAST Upgrade to CAST-V), 707.55567

• Directional Sub Assembly, 707.55572

• Scanner Assembly, 707.55531




Figure 1 -1: CAST-V Tool




Equipment ListTable 1 -1: CAST-V Tool Primary Components

DESCRIPTION PART

CAST-V Tool 707.55600

CAST-V Instrument 707.55598

CAST-V Directional Sub 707.55572

CAST-V Scanner 707.55531

CAST-V Transducer Heads

3-5/8 in. head assembly 707.55525

4-3/8-in. head assembly 707.55542

5-5/8-in. head assembly 707.55672

7-in. head assembly 707.55670

CAST-V Transducers

250-kHz cased-hole (white) 707.31495

350-kHz cased-hole (brown) 707.31449

450-kHz cased-hole (black) 707.31473

380-kHz openhole (brown focused face) 707.31408

Table 1 -2: Additional Equipment

DESCRIPTION PART

Oil Fill Gauge (used to check the Scanner oil fill) 707.55673

Chassis Insertion/Removal Tool, 3-5/8-in. DITS 3.30014

Thread Protector, Male, Standard DITS 3.29994

Thread Protector, Female, Standard DITS 3.29996

Calibration Stand Assembly 707.55635

DITS 19-Pin Breakout Box 3.48655

Spanner, 3-5/8-in. Standard DITS 0.96655

CAST-V Service Manual (order through Records andSupply in Houston, TX)

770.00696

Fanfold Paper 770.10577

Engineering Documentation Package (EDP) 770.00710

DITS 37-Pin Jumper Cable 3.48659

DITS 19-Pin Jumper Cable 3.48657

CAST-V Field Operations Manual - Image Mode 770.00700

CAST-V Field Operations Manual - Cased-Hole 770.00709



Click here for the current Tool Technical Specifications data sheet. - Cased-Hole Mode

Click here for the current Tool Technical Specifications data sheet. - Imaging Mode

http://halcape001.corp.halliburton.com/PublishedDocs/Specification_D00132777_1.doc







SpecificationsMechanical, electrical, and measurement specifications are included in this subsection.

Mechanical

• Maximum operating temperature: 350°F (177°C)

• Maximum operating pressure: 20,000 psi (137,900 kPa)

• Length: 17.9 ft (5.45 m)

• Diameter: 3-5/8 in. (9.2 cm)

• Electronics Assembly: 122.15 in. (3.1 m)

• Directional Sub Assembly: 36.5 in. (0.93 m)

• Scanner Assembly: 56.1 in. (1.43 m)

Electrical• 120 ±18 Vac, 60 Hz, 250 mA (W5)

• 150-Vdc, 1.5 A (Sorenson)

• Full load requirements: 30-Wac, 225-Wdc

Measurement

This subsection contains the measurement accuracy specifications for the CAST-V in

image and cased-hole modes. The minimum and maximum borehole diameters in which

the tool will operate are included.

Image ModeSensor Type: Piezoelectric on rotating head

Firing Rate (shots/scan): 200

Vertical Scan Rate: 40 scans/ft at 21 ft/min

Telemetry System: Digital Interactive Telemetry System

Compatibility: DITS (requires up to 288 words/frame)

Principle: Ultrasonic Pulse Echo

Azimuthal Sampling: 1.8°

Vertical Sampling (Software): 0.2 in.

Logging Speed: 21 ft/min

Primary Curves: Reflected Amplitude and Travel Time

Secondary Curves: Radius, Azimuth, Relative Bearing, Deviation, andFluid Transit Time

Minimum Diameter Hole: 4.5 in. (11.4 cm)

Maximum Diameter Hole: 12.50 in. (31.75 cm)




Cased-Hole ModeSensor Type: Piezoelectric on rotating head

Firing Rate (shots/scan): 100

Vertical Scan Rate: 4 scans/ft at 30 ft/min

Telemetry System: Digital Interactive Telemetry System

Combinability: FWST, CCL, NGRT, SDDT, and DSNT.

DITS (requires 48 words/frame)

Principle: Ultrasonic Pulse Echo

Azimuthal Sampling: 3.6°

Vertical Sampling: 6.0, 3.0, or 1.0 in.

Logging Speed: 60, 30, or 10 ft/min

Primary Curves: Reflected Amplitude, Radius, Acoustic Impedance,and Casing Wall Thickness

Secondary Curves: Deviation, Relative Bearing, Compressive Strength,Fluid Transit Time, and Mud Impedance

Minimum Diameter Hole: 5.5 in. (12.7 cm)

Maximum Diameter Hole: 13.375 in. (33.97 cm)

Safety

Personal Safety

Avoid electrical shock hazards. Disconnect power from the equipment before performing

maintenance and repairs.

Support the tool on dollies, sawhorses, workbenches, or other suitable tool supports

when servicing. Ensure that the tool is secured to the work surface to prevent it fromrolling.

Use the proper lifting technique when handling the CAST-V.

Equipment Safety

Use extreme caution when lifting the CAST-V Scanner Assembly. The Scanner’s motor

shaft can be easily bent or damaged if it is not handled properly. Lift and lower the

Scanner Assembly in the well separately from the CAST-V Electronic Assembly.

Use extreme care when handling the CAST-V transducers. These devices are sensitive to

shock and vibration. Avoid bumping or hitting these devices.Ensure that the CAST-V pressure-balance system contains oil to the proper level and that

the oil is contaminant-free after every logging job. Both contaminated oil or low oil

levels can cause severe damage to the tool even if the tool is operating in wells where the

temperature and pressure are within normal specifications. Contaminated oil and low oil

levels significantly reduce the operating temperature and pressure limits of the tool.

Do not exceed CAST-V pressure, temperature, or electrical limits during operation.

Do not “spud”; because damage to the motor shaft or face seal may occur.




07/97 770.00696 - NW Theory of Operation 2-1

Section

2

Theory of Operation

IntroductionThis section contains a discussion of the tool in increasing detail. Areas discussed in this

section include:

• A basic discussion of how the tool makes the measurement.

• A hardware functional description of overall equipment operation supported by block

diagrams. The block diagrams show major functional blocks; a discussion follows

the block diagram.

• A block description which explains the major functions but not the circuits.

• A circuitry description section that discusses the circuitry for each of the major

functions of the assembly. To make complex assemblies easier to read andunderstand, some circuit discussions are broken down into simpler schematics and

discussions.

Nature of the MeasurementThe CAST-V tool measures characteristics of the borehole wall or casing using a high-

frequency pressure pulse. During operation, transmitted ultrasonic pulses interact with

the borehole wall in a way that causes pressure waves to travel back to the tool. The

transducer used to transmit the original pulse then converts these pressure variations to a

voltage waveform. The digitized values of this waveform are the basis for all CAST-V

images and curves in both cased and open boreholes.

Physical Principles

A model of a transducer placed approximately 1 in. from the inner wall of a 0.3-in. thick

casing is shown in Figure 2-1.



2-2 Theory of Operation 770.00696 - NW 07/97

Figure 2-1: Transducer Model

Images computed using a model show a magnified view of how pressure waves

propagate in the area around the model after the transducer is fired in a cased borehole

(See Figures 2-2 through 2-5). Borehole pressure variations are presented in cross section

as changes in intensity. Pressure waves are shown for both free pipe and bonded pipe at

four different time intervals after transducer firing.

Figure 2-2 shows the pressure waves at approximately 14 ps after transducer firing and

before they arrive at the casing. The active area of the transducer is approximately 2.5

water wavelengths wide, causing the circular wavefronts shown. The greatest pressure

intensities occur in a triangular region in front of the transducer.

Figure 2-2: Pressure Waves 14 ps After Firing




Figure 2-3 is taken at approximately 24 us after transducer firing and just after the pulse

strikes the casing. The pressure amplitude in the zone behind the bonded casing is larger

than in free pipe as energy is transferred into the cement.

Figure 2-3: Pressure Waves 24 µs After Firing

Figure 2-4 shows the pressure waves traveling back to the transducer at approximately 29

ps after transducer firing. The curved wavefronts of the output waves have been changed

to flat ones because of the focusing effect of the casing. The wavelengths of the waves

behind the bonded casing are longer than those in free pipe because of the higher

acoustic velocity of cement relative to that of water.





In Figure 2-5, the reflected wavefronts arrive back at the transducer approximately 37 ps

after the initial transducer firing. The waves caused by the resonance ringing of the

casing follow behind the higher intensity reflected waves. This difference in amplitude

between the reflected and resonance waves is more than 10:1 and requires that the gain

be increased while the casing waveform is being recorded.


From the figures, it is apparent that the resonance waves (the area behind the reflected

waves) in the free pipe are of higher intensity than those in bonded pipe. This amplitude

difference is the basis of the bonding measurement. Cased-hole resonance waves are of

lower amplitude and fade more quickly than those in free pipe. Waveform recordings

start when the transducer is fired and last for a time that ensures that all pressure

disturbances have faded in the area around the tool.

Acoustic WaveformsFigure 2-6 shows the voltage waveforms at the transducer caused by pressure variations

in the borehole fluid. The starting point of the time axis is the time that the initial pulse

is fired from the transducer. All images created by the CAST-V tool are made by various

characteristics of these waveforms.

Two raw CAST-V measurements are taken directly from the waveform. The reflected

pulse amplitude and the total time of a pulse’s trip from the transducer to the borehole

wall and back are made in all operating modes and are the only measurements made inimage mode. The peak amplitude is used to image the borehole without further

processing. Fairly small textural features of approximately 0.05 in. can cause a detectable

change in amplitude. The transit time, on the other hand, has much lower spatial

resolution, but it can be used with the fluid velocity measurement to observe changes in

distance from the transducer face to the borehole wall on the order of 0.01 in.




Figure 2-6: Voltage Waveform, Open Hole

Tool Processing: Window Sum and ThicknessThe amplitude and transit time values are taken directly from acoustic waveforms and do

not require any further calculation by the tool itself. In the cased-hole mode, two

additional parameters are derived that do require processing. Downhole processing

reduces the amount of data sent uphole by a factor of 16:1.

All downhole calculations are made on a section of the waveform that starts 15 ps after

the initial parts of the reflection pulse arrive back at the transducer (Figure 2-7). This

delay allows most of the reflection to fade so that the majority of the signal is caused by

the vibrating casing. A period of 12.8 ps (64 ADC samples) are used in the measurement

window.

Figure 2-7: Voltage Waveform, Cased Hole




The simplest calculation on the resonance window is to simply add the 64 individual

sample values. Negative values are converted to positive values before addition. This raw

sum is the basis for all bonding measurements made by the CAST-V. The smaller the

raw sum value, the greater the degree of bonding.

The thickness calculation is the second, more complex calculation made on the resonance

window. It is calculated from the resonance frequency of the casing and the velocity of sound in steel. For any wave motion, the velocity of propagation is equal to the product

of its wavelength and its frequency. Most of the energy of vibration in the resonance

window is assumed to come from the pipe’s fundamental mode of resonance, in which

the thickness of the casing is equal to twice the wavelength. If the velocity of

propagation in steel is 19,029 fps, the thickness can be calculated from the frequency of

the waveform using:

The CAST-V processor first makes an estimate of the resonance frequency using the

average transit time for the 100 shots in a single horizontal sweep. This average iscombined with the fluid acoustic velocity to determine the nominal internal diameter of

the pipe. The outer diameter of the pipe is entered at the surface and then downlinked to

the tool. The first thickness estimate is then just one half of the difference between the

inner and outer diameters. This thickness is converted to a frequency by the use of the

relationship above.

The first resonance frequency estimate is then refined with the Fourier transform. The

magnitude of the frequency transform is calculated at steps corresponding to 0.002-in.

thickness changes. Magnitudes are calculated until a peak is found. This frequency is

then converted to thickness and encoded for transmission uphole. Much of the computing

time required in the tool’s high-speed microcomputer is used in the thickness calculation.

Transit Time CalculationsThe distance to the borehole wall, hole radius, tool eccentering, casing ovality, and fluid

acoustic velocity values are all calculated from the transit time of the main and mud-cell

transducers. The distance image is the product of the transit time from the main

transducer and the fluid acoustic velocity from the mud-cell transducer. The radius image

is a distance image corrected for tool eccentering, in which the points of reference for the

distance measurements are transposed from the center of the tool to the center of the

hole. Tool eccentering is the maximum difference between any two distance values that

are 180° apart. Ovality is calculated using the maximum difference of any two diameter

measurements that are 90° apart.Fiuid acoustic velocity is calculated from the transit time of the mud-cell transducer.

This transducer always fires at a target 1.25 in. from the face of the transducer. Fluid

velocity is given by:

where Tm is the round-trip transit time of the mud-cell pulse.




Acoustic ImpedanceThe apparent acoustic impedance of the material behind the casing is calculated uphole.

The value is obtained from the window sum value calculated by the tool. The sum is first

normalized to the amplitude of the reflected pulse to make a raw normalized sum value.

This step removes the effect of changes in fluid attenuation between shots.

The next step is to compare the normalized sum value at the point measured to that

observed in pipe bonded with a known impedance. Normally, this is totally unbonded

free pipe. This calibration step removes variations due to transducer sensitivity, casing

thickness, and casing size. The ratio value is used directly to calculate acoustic

impedance and is given by:

The value for the normalized sum at the calibration (cal) point can be obtained by

logging a section of free pipe, by obtaining measurements from a calibration fixture

containing the same size of casing as that being logged, or by mathematically modeling

the waveform expected at the cal point with the reflection waveform as an input.

The final step is to convert the calibrated ratio of normalized sums to acoustic

impedance. The relationship used is:

impedance in Mrayls = cal point impedance -10 x thickness x ln(ratio),

where thickness is in inches and the cal point impedance is 1.5 Mrayls in free casing with

water behind it.

Directional MeasurementsThe CAST-V tool includes a two-axis directional sub to orient acoustic images. The

surface software can also orient images with directional data from the SDDT. Figure 2-8

shows the orientation angles used in the CAST-V service.




Figure 2-8: Azimuth and Relative-Bearing Diagram

The directional sub contains two sets of sensors. One set measures the direction of the

earth’s magnetic field. The other set measures the earth’s gravity. Both measurements are

made in a plane perpendicular to the tool chassis and are referenced to the DITS

interconnection alignment pin. Values derived from the magnetic sensors are used to

provide the angle (azimuth) between the DITS pin and magnetic north. Values derivedfrom the gravity sensors (accelerometers) are used to calculate the location of the DITS

pin relative to the high side of the hole (relative bearing) and the deviation of the hole

from vertical. Each set of sensors consists of two sensors mounted at right angles to each

other.

Calculated angles are measured looking downhole from the indicated direction and to the

DITS button in a clockwise direction as shown in Figure 2-8.




If the tool hangs perfectly vertically, the accelerometer’s output voltage is near zero. The

indicated relative bearing becomes erratic, and the indicated deviation approaches 0°.

The relative bearing stabilizes with approximately 3° of tilt.

Azimuth reading cannot be used in casing because of the magnetic shielding of the tool

from the earth's magnetic field. In open hole, azimuth readings are useful unless the tool

centerline aligns with the earth's magnetic field, causing sensor output voltages toapproach zero.

The deviation and relative bearing are calculated as follows:

and

where

Gx = accelerometer x-axis output voltage.

Gy = accelerometer y-axis output voltage.

Gtot = the output voltage of either Gx or Gy when measuring a 1.0 gravity field. (4.00 V

in the case of the directional sub)

The Quadrant Angle is determined by examining the signs of Gx and Gy.




Functional Description

System Functions

Automatic Gain Control

Changes in mud attenuation and target reflectance cause the amplitude of the main

transducer signal to vary over a large range. The amplitude of the casing resonance

vibration is less than one tenth the amplitude of the reflected pulse. The differing types

of transducers used in the tool can vary in sensitivity by a factor of over 20: l. Automatic

gain switching is required to cover this large range of signal amplitudes at the

frequencies involved.

To measure the reflected pulse, the tool uses the amplitude of the current transducer

firing to set the gain of its amplifiers for the subsequent shot. Similarly, the tool can alsodetect the maximum amplitude in the resonance window and automatically set the gain

for that part of the waveform. The amplifiers in the tool are capable of changing gains

quickly. In the cased-hole operating mode, the system detects the reflected pulse and

changes the amplifier gain for resonance within the 15-ps period before the start of the

window. Figure 2-9 shows the actual cased-hole waveform as seen at the input to the

digitizer in the tool.

Figure 2-9: Cased-Hole Waveform

Amplifier gains are changed in 3-dB steps, each one multiplying the input signal by a

factor of 1.4. The gain of the system has a range of 32 steps or 96 dB. Waveform

amplitude-related values, such as the peak of the reflected pulse and the sum of the 64

ADC points within the resonance window, are sent uphole with the gain code related to

them.




Outputs: Scan Data Formats

Tool output data is logically organized into 407 word scans. A scan contains all the data

recorded by the tool for each horizontal sweep in the log images (Table 2-1). Scans are

recorded and stored in the tool at a rate set by the motor speed. They are sent uphole at arate set by the DITS. Untransmitted scans are overwritten. If a new scan is not available

when the telemetry system needs it, the last full scan recorded is sent again. Standard

DITS limits the logging speed in the image mode to approximately 20 ft/min. Processing

time requirements in the tool limit the cased-hole mode logging speed to 30 ft/min.

Table 2-1: Tool Data Scan Format

Word Uplink Data (Cased Hole) Uplink Data (Image Mode)

0 Scan Sequence Number Sequence number

1 Inclinometer X Inclinometer X

2 Inclinometer Y Inclinometer Y

3 Magnetometer X Magnetometer X4 Magnetometer Y Magnetometer Y

5 Slow channel ID Slow channel ID

6 Slow channel data Slow channel data

7 Peak Amp Gain/Peak Amplitude Peak Amp Gain/Peak Amplitude

8 Transit time Transit time

9 Resonant Window Sum Peak Amp Gain/Peak Amplitude

10 Resonant gain / thickness step Transit time

Peak Amp Gain/Peak Amplitude

Transit time

Resonant gain / thickness step

Resonant window sum

403 Peak Amp Gain/PeakAmplitude Peak Amp Gain/Peak Amplitude

404 Transit time Transit time

405 Resonant window sum Peak Amp Gain/Peak Amplitude

406 Resonant Gain / Thickness Step Transit time

0 Scan sequence number Scan sequence number

1 Inclinometer X Inclinometer X

2 Inclinometer Y Inclinometer Y

3 Magnetometer X 3 Magnetometer X

Scans are sent uphole in multiple DITS frames. The single DITS rates are the maximum

108 kbps for the image mode. This rate is also used in the cased-hole combination

service that includes the M305 FWST with the 3-ft and 5-ft receiver tip. A 27-kbps

telemetry rate is used in the cased-hole mode when the tool is run alone. The image

mode sends a scan uphole using 32 word blocks, 9 blocks per 50-ms frame. The cased-

hole mode sends scans uphole in 24 word blocks, 2 blocks per 50-ms frame.




A test mode is also available that sends a single raw acoustic waveform uphole with each

scan. This mode can be used before logging to observe the output of the transducer and,

if necessary, to adjust the gate opening point.

Slow Channel Data Acquisition

A number of auxiliary data values are sent uphole with the acoustic data (Table 2-2).

This information changes slowly and does not need to be reported to the surface system

as often as the acoustic and directional measurement. Slow channel data is sent uphole at

a rate of one word per scan. An offset value into the slow channel data is also sent.

Table 2-2: Slow Channel Auxiliary Data

Channel Description (Cased-Hole) Description (Image Mode)

1 Casing OD Casing OD (not used)

2 Effective tool radius Effective tool radius (not used)

3 Motor speed Motor speed

4 Motor voltage Motor voltage5 Motor current Motor current

6 Head ID (not used) Head ID (not used)

7 Temperature Temperature

8 Firmware version Firmware version

9 Tool mode Tool mode

10Mud-cell peak gain / Mud-cell peakamplitude (Hi Byte/Lo Byte)

Mud-cell peak gain / Mud-cell peakamplitude (Hi Byte/Lo Byte)

11 Mud-cell transit time Mud-cell transit time

12 Mud-cell sum Mud-cell sum (not used)

13Mud-cell sum gain / Mud-cell thicknessstep (Hi Byte / Lo Byte)

Mud-cell sum gain / Mud-cell thicknessstep (Hi Byte / Lo Byte) (not used)

14 Gate start Gate start

15 Waveform mode flag Waveform mode flag

16 RESERVED RESERVED

Inputs: Tool Commands

The CAST-V system is designed to use a minimum of required inputs from the surface.

All control inputs are set to a default value that usually works for logging. Two inputs

that must always be specified before logging cased-holes are the casing OD and the

effective head radius (the distance from the transducer face to the center axis of the tool).

The surface system reports an error until these values are entered.

Other commands include

• Set Operating Mode - select between cased-hole and image operating modes. This

command is usually sent automatically by the surface software based on the service

selected.




• Set Gate Opening Point - set the starting point in the waveform for the search for the

reflection peak. This command is sent in the openhole mode when the gate start

position is changed in the CAST-V tool menu.

• Toggle Waveform Display - toggle between normal operation and waveform

monitoring mode. This command is sent in either mode when the waveform

monitoring tool menu item is selected. The surface software disables waveformmonitoring while logging.

Scanner Assembly (Drawing 707.55531)

Description

The scanner assembly (Figure 2-10) contains the primary CAST-V acoustic sensors. A

brushless dc motor turns the main acoustic transducer. The electrical connection to the

main transducer is made through a slip-ring assembly mounted between the head and the

motor. A resolver, mounted above the motor, continuously senses the position of the

transducer face relative to the DITS alignment pin.

A second, fixed transducer is mounted above the motor and resolver with its face

exposed to the borehole fluid. This sensor continuously fires at a 0.3-in. thick plate

mounted 1.25 in. from the transducer. From this distance and the time of flight for each

pressure pulse, the acoustic velocity of the borehole fluid is calculated.

The motor and sensor in the CAST-V scanner operate in a bath of Exxon Turbo Oil 2380

(P/N 0.81792). A piston compensator maintains borehole pressure inside the scanner

assembly. A high-pressure bulkhead connector allows for the required electrical

connections.




Figure 2-10: CAST-V Scanner




Block Diagram

The two acoustic transducers in the scanner are of the pulse echo type (Figure 2-11). The

same transducer is used both as a transmitter and a receiver. Firing pulses and the

returning waveforms are connected by two wires from each transducer to the electronicscartridge. The mud-cell transducer is connected directly through the pressure bulkhead

and the 37-pin DITS type connector at the top of the scanner. The rotating main

transducer additionally goes through slip-ring contacts.

The three-phase, brushless dc motor has three wires. Power and ground are connected to

these wires by precisely controlled electronic switches, causing the motor to rotate

clockwise (as viewed downhole). Switch control is provided by circuitry reading the

motor shaft position from the resolver transformer fastened to the top of the motor. The

resolver and associated electronics determine the position of the motor rotor within 0.02°

. Motor speed is proportional to motor voltage, and motor torque is proportional to motor

current. Maximum motor ratings are 150-Vdc at 1.7 A.

Figure 2-11: CAST-V Scanner Block Diagram




Transducers

• Transducers used in the CAST-V tool are made up of three parts (Figure 2-12):

• • iezoelectric active element that converts pressure changes to and from voltage

changes

• • ound-absorbing backing material to prevent transmission of acoustic pulses intothe tool

• • poxy outer covering that encapsulates the transducer and protects it from

borehole fluids

Figure 2-12: CAST-V Transducer

The piezoelectric ceramic elements used are manufactured as both circular disks and as

rectangles. The thickness of the element determines the frequency of its maximum

output. Backing materials absorb pressure waves launched from the rear of thepiezoelectric element.

The transducers used in cased holes are significantly different from those used in open

holes. They have rectangular elements and an alignment groove that ensures proper

orientation. They are designed to have a wide-frequency bandwidth and short transmitted

pulse. This allows them to be used over as large a range of casing thicknesses as possible

and prevents the reflected waves from interfering with the acoustic waves generated by

the resonating casing. The openhole transducer does not have this requirement and is

designed primarily for maximum output.

CAST-V cased-hole transducers are manufactured with peak output frequencies of 250,

350, and 450 kHz. The type of transducer used is determined by the thickness of casing

to be logged, with thicker casings requiring lower peak frequencies. The openholetransducer has a peak output frequency of 380 kHz. The 450-kHz cased-hole transducer

can be used in boreholes containing high attenuative fluids; however, image resolution is

slightly reduced.




Directional Sub (Drawing 707.55572)

Description

The four-axis directional sub shown in Figure 2-13 is provided as a smaller, low-costalternative to the full six-axis SDDT. A directional measurement is required to orient

CAST-V images to a fixed point of reference, such as north. Images oriented with the

tool body alone rotate slowly as the tool rotates on the cable.

A two-axis flux-gate magnetometer is used to determine azimuth, the angle as measured

from north to the DITS alignment button. Signals from the magnetometer sensors are

processed by an analog compass board that provides two dc outputs. These outputs are

proportional to the magnitude of the earth’s magnetic field in each of two orthogonal

axes in a plane perpendicular to the center axis of the tool.

A similar function is provided by a two-axis accelerometer package. This self-contained

unit has both the sensors and the electronics required to provide two outputs proportional

to the magnitude of gravity in a plane perpendicular to the tool axis. When the tool isvertical, both sensors are nearly horizontal and read zero. This accelerometer package is

the same as the one used in the Pulse Echo Tool (PET).

Figure 2-13: CAST-V Directional Sub




Block Diagram

See Figure 2-14.

The analog signals and power for the directional sensors are carried through the compass

board. The directional sub itself contains all the required analog signal-processingelectronics. The main function of the compass board is to convert the 27-kHz signals

from the saturable inductor into voltages proportional to the earth’s magnetic field.

Power for the compass board is provided by power supplies in the electronics cartridge.

Output voltages from the inclinometer are adjusted on the compass board to values

suitable for the slow ADC in the tool electronics.

The directional sub also contains the through wiring necessary to connect the sensors and

motor in the scanner to the electronics cartridge.

Figure 2-14: Directional Sub Block Diagram




Electronics Cartridge (Drawing 707.55598)

Description

The primary function of the CAST-V electronics cartridge is to record and preprocess the

high-frequency acoustic waveforms from the main and mud-cell transducers. The

relatively high sampling rate required for imaging prevents the transmission of the entire

raw recorded waveform. The required waveform parameters are extracted by the tool, and

these values are sent uphole for further processing and display. The electronics cartridge

also drives the dc scanning motor, handles signals from the resolver, and acquires the

directional data.

Block Diagram

The electronics cartridge block diagram (Figure 2-15) shows the path of acoustic

information as it travels from the transducer to the RTU-B interface. Analog waveformsare amplified, digitized, and then preprocessed by this series of circuit boards. Processed

data are sent to the RTU-B for transmission uphole.

Figure 2-15: Electronics Block Diagram




The preamplifier/fire board provides the direct interface to the acoustic transducers. Two

transducers can be attached to the board, but only one can be selected at a time. Firing is

done with a 400-V, 1.2-µs pulse timed from the resolver position. The board also has a

receiver preamplifier with gains of -24, 0, and +24 dB. This gain is controlled

automatically by the DSP (Figure 2-16).

Figure 2-18: DSP Block Diagram

The preamplified waveform is then sent to the variable gain amplifier(VGA)/ADC. The

VGA has sixteen 3-dB gain steps that, when combined with the preamplifier gains, give

a total of 32 unique 3-dB system gain values. The automatic gain system provides a

nearly constant level analog signal to the input to the ADC. The ADC operates at a

sampling frequency of 5 MHz and has a range of +/- 2 V. The frequency range of the

CAST-V acquisition system ranges from about 40 kHz to greater than 1 MHz. The ADC

sends a continuous stream of 0.2µs, 8-bit samples to the DSP/gate array board. Logic, at

this point, determines which samples in the stream are recorded and processed.

All CAST-V waveform processing and much of the tool control are done by theDSP/gate array board. The firing cycle is initiated by a start pulse from the resolver-to-

digital (R-to-D) converter board. The DSP then sets the amplifiers in the tool to the

proper gain and sends a fire pulse to the preamplifier/fire board. Logic in the gate array

causes the ADC output values to be recorded in memory buffers. The two buffers

available are each capable of recording for up to 409.6 ps from firing. As the stream of

waveform samples passes through the gate array, they are searched for the reflection

peak. The magnitude and time from firing for this peak are saved in gate array registers.




In the cased-hole mode, the VGA gain is switched at the proper time in the waveform to

provide the extra gain needed to record the resonance section. The resonance window is

also searched for a peak in real time. This value is used by the DSP for control of the

resonance gain.

After firing the current shot, the DSP begins processing the data from the previous firing.

The first-arrival amplitude is tested to determine the gain needed for the next shot. Incased holes, the peak value in the resonance window is checked to set the next resonance

gain. The peak time values reported by the gate array are used as the starting point for a

search for the true transit time. The DSP searches backwards in the waveform buffer to

find the baseline before the first cycle of the reflection pulse. Transit time is defined as

the end of this baseline, as shown previously in Figure 2-6.

The DSP does further processing on the resonance window in cased holes. The absolute

values of the 64 resonance window samples are summed for the bonding calculation. The

peak frequency component of the waveform section in the window is calculated last. The

majority of the DSP processing time is required by the frequency calculation.

After processing, the DSP sends the results to the V40 telemetry CPU (Figure 2-17) to be

organized into scans. In the openhole mode, the reflection amplitude, reflection gain, and

transit time are sent. The cased-hole mode additionally sends the resonance sum,

resonance gain, and thickness. All DSP processing is done in the time between each

firing of the main acoustic transducer.

Figure 2-17: V40 Telemetry CPU Block Diagram




The V40 takes the DSP result data from each transducer firing and packages it into scans.

Auxiliary data are recorded and attached to the beginning of each scan. The board has

three scan-sized memory buffers. One is used to build a new scan as it is acquired from

the DSP. Another is used to freeze the scan data as it is sent uphole. The third buffer is

used to synchronize the acquisition process that operates at a rate determined by the

motor speed with the telemetry process, the rate of which is set by the DITS. The V40continuously stores DSP data to the input buffer. When a full scan is acquired, this buffer

is switched with the synchronizing buffer. The telemetry process continuously sends

blocks of data from the output buffer. When it reaches the end of each scan, it checks the

synchronizing buffer to see if a new scan is available. If a new scan has been acquired,

the output buffer is switched with the synchronizing buffer. If not, the output scan is sent

again. A counter in the header of each scan allows the uphole system to detect when this

occurs. Excessive scan duplications indicate that the motor is turning too slowly for the

current logging speed.

Output data from the output buffer are loaded into a first-in, first-out (FIFO) memory

part on the V40 board. The RTU-B takes data from this FIFO serially, one bit at a time.

Synchronizing signals are sent from the RTU to the V40 at the beginning of each

telemetry block.

A limited number of input commands can be sent to the tool to control its mode of

operation. These commands are sent from the RTU-B to the V40. Most commands are

then sent on to the DSP to control waveform processing.

The electronics cartridge also does several required auxiliary tasks. The R-to-D converter

board receives the sine and cosine outputs from the resolver in the scanner and calculates

a number between 0 and 1023 proportional to the angular position of the motor shaft.

This number is decoded on the R-to-D board to create a sync pulse at the zero point and a

start pulse at each firing position. At the zero point, the transducer is aligned with the

DITS connector alignment pin.

The slow ADC board contains a 12-bit resolution ADC used primarily to convert thefour output signals from the directional sub. Additional values measured include the

output of the temperature sensor in the accelerometer package, the motor voltage, and the

motor current. These measurements are sent directly to the V40 CPU through an

asynchronous serial link.

The power supply in the electronics cartridge provides power to all components of the

CAST-V tool, except for the scanning motor. Regulated voltages for various sections

include +5 Vdc and +/-15 Vdc. A 400-Vdc source is provided to fire the acoustic

transducers. DC power for the motor is routed directly to the commutator board from the

cable through the primary windings of the instrument power transformer.




Circuit DescriptionsThis subsection describes board-level operations of the CAST-V.

Remote Telemetry Unit RTU-B (Drawing 3.85601)

The RTU is the interface circuit in each tool that connects the tool electronics to the

telemetry sub at the top of the stack. The RTU-B has been designed to operate with

either the standard DSTU telemetry sub or the D2TS sub used in the DITS II system at

twice the telemetry rate. For a more detailed discussion of the RTU-B and the telemetry

system, refer to publication 770.00491, D2TS Service Manual.

Each RTU in a DITS toolstring has a unique address. Communication between a tool and

the telemetry sub is in half-duplex. The RTU only transmits on command from the

DSTU/D2TS. When a send data command is received, data words are requested from the

tool acquisition electronics. The data words are formatted according to the MIL-STD-1553 Manchester encoding used on the intertool serial bus and sent out to the telemetry

sub. Other downlink commands are sent to the tool by the telemetry sub and the RTU.

Tool commands (mode codes) can optionally include an additional command data word.

The RTU-B interface printed circuit board consists of

• 1553 bus interface transformer

• 1553 transceiver

• two Actel field-programmable gate arrays (U1 and U3)

• 5.2224-MHz oscillator

• header for JMP1 to JMP4, J4, J5, and J6

• two Positronic connectors (J1 and J2)

• filter circuit consisting of L1, C1, and C2

The Actel gate array U2 contains the 1553 encoder/decoder circuitry which converts

NRZ data from the tool to the 1553 Manchester format of the intertool bus and the

D2TS. Commands from uphole are decoded back to serial NRZ. Data can be taken in

either 8 or 16 bits parallel from header J4, shifted serially to header JMP1, and returned

to gate array U2 for encoding.

Gate array U3 contains the control logic for the RTU-to-tool interface. It validates

commands and data received from the D2TS and sets the proper flags for the tool to

indicate either transmit-receive data commands or transmit-receive mode commands. TheRTU address in each command is compared to that of the tool in the gate array before

any communication.

The 5.2224-MHz oscillator provides the master timing for the board, including setting

either the low- or high-speed ITB bit rates. DITS I tools are set to 217.6 kbps, while

DITS II tools are set to 435.2 kbps. The ITB rate is command selectable if the header

JMP4 is strapped from pin 1 to pin 8. The bit rate select command is XXE9H, in which

XX is the tool address. For example, if the tool’s address is 51H, then the command is

51E9H. The RTU-B always powers up at the 217.6-kbps rate as a default.




Header JMP1 must be strapped properly for correct operation of the RTU. If the RTU-to-

tool interface is serial and the tool can keep data ready on the serial input, then pin 1 is

strapped on JMP1.

The tool must be able to send data within 27µs after the send data command to use this

option. If the tool cannot respond this fast, then pins 2 and 7 are strapped on JMP1. This

gives approximately 92 ps for the tool to get its data ready. If the tool's interface isparallel, then pins 4 and 5 are jumpered on JMP1.

If the RTU-B is used to replace a single-board serial RTU, the Positronic connectors J1

and J2 are used. If the RTU-B replaces a two-board parallel RTU (data and control), then

headers J4, J5, and J6 are used instead.

Header JMP2 is used to select between 8- and 16-bit parallel operation. Header JMP3 is

set to the RTU-B address of the tool.

V40 CPU Board (Drawing 707.55666)

The V40 CPU board takes processed data from each firing of the acoustic transducerfrom the DSP board and stores it in memory. These data are collected into groups of 100

shots for the cased hole and 200 shots for the image mode. This group of information

corresponds to all the data recorded for each horizontal scan in the images presented on

the log. The following description of the operation of the V40 board is shown in the

block diagram in Figure 2-17.

The V40 CPU board consists of

• 6-MHz NEC V40 microprocessor with internal peripherals

• 32 kbytes of static RAM and 32 kbytes of EPROM

• Actel field-programmable gate array

• FIFO memory to temporarily hold telemetry data

The NEC V40 (U1) is an 8-bit microprocessor similar to the one used in the IBM PC.

The part has built-in peripherals including three 16-bit counter-timers, seven-level

programmable interrupt controller, three-channel DMA controller, and asynchronous

serial I/O port. The processor has 20 address bits that allow access to up to one megabyte

of external memory.

Most of the communication between the CPU and external memory or peripherals occurs

through a three-state address and data bus. To minimize the number of pins on the part,

the data bus and lower eight address lines share the same eight output lines. Latch U6

separates the lower address lines and buffers them. Similarly, bidirectional buffer U7

drives the data lines, and buffers U8 and U9 drive the control output lines and the

remaining address lines. All outputs from the bus taken off the board are buffered.

There are two memory parts on the V40 board. Static RAM U2 is used primarily to

accumulate the data from each shot until all the data for a complete image scan have been

received. EPROM U3 contains the operating program for the microprocessor. This

EPROM is also used for storage of the program for the AT&T DSP32C DSP on the

DSP/acquisition control board. A new program is loaded into the DSP at tool power-up

and when the operating mode is changed at the surface.




Gate array U4 is used to implement the interface between the V40 and the DITS. Control

and commands from the RTU are transferred through it. In addition, logic is included in

the gate array to decode the processor addresses and create address-select lines for both

the on-board peripherals and the DSP board.

The FIFO (U5) is used to temporarily store the information for a full horizontal scan

while it is sent uphole. The FIFO also provides the conversion between the 8-bit paralleldata of the three-state bus and the serial data required by the RTU-B. When the FIFO

becomes empty, it flags the V40 through the gate array. The V40 then transfers the last

complete scan acquired to it from the DSP. This telemetry-transfer mechanism is the

same in both the cased-hole and image operating modes.

Data are transferred from the DSP board to the V40 using DMA. The rate of data transfer

in the openhole mode is approximately five times that of the image mode and must be

handled by the hardware directly.

In the openhole mode, two data words are transmitted to the V40 with each firing of the

transducer. A new, 200-point horizontal scan line is acquired with each rotation of the

motor. This requires that data be transferred between the DSP and the V40 at a rate of

approximately 24 kbps. An internal DMA controller in microprocessor U1 transfers data

1 byte at a time as it becomes available from the DSP. Memory-enable signals on the bus

are generated by the hardware DSP controller without storing data for a new scan. At that

time, auxiliary information read from the slow ADC board serial line is stored with the

scan. Motor speed is calculated in the V40 by observing the rate at which these sync

pulses occur.

In the image mode, four data words are transmitted with each transducer firing. Scans are

100 points long and require five rotations of the head for acquisition. A new set of four

words is available approximately every 5 ms. The DMA cycle is used only to transfer the

four words from a single firing to a small temporary buffer. The V40 program polls the

DMA controller and, when a new shot is available, transfers the information to the

proper place in the scan buffer.

The two processes of receiving data from the DSP and sending data to the RTU happen

at different speeds. To keep them in sync, the V40 buffers scan data for both. If the

motor is turning at the proper speed, the acquisition process happens faster than the

telemetry process. The latest scan acquired is sent to the telemetry link when it needs

one. If a new scan is acquired before the previous one is sent, the old scan is discarded,

and the new one takes its place. (Each scan has a sequence number to uniquely identify

it.)

The V40 board continues to acquire and transfer scans as long as the motor is turning and

data are being requested by the RTU.




Commutator Board (Drawing 707.55559)

The commutator board provides the FET switches and driver circuitry to interface the

resolver board to the motor in the scanner of the CAST-V tool.

The commutator board has three sets of FET switches connected to switch voltage from

the auxiliary power connection of the tool to the motor windings. The motor requires that

this power be applied to the motor windings in a controlled manner determined by the

motor’s rotor position. Signals provided by a shaft-mounted resolver working with the

R-to-D board control the FET switches of the Commutator Board.

Refer to the "R-to-D Board (Drawing 707.55561)" for information about the

development of the logic level signals that control the timing of the closures of the FET

switches.

Circuit Description

The motor used in the scanner has three windings connected in a Y configuration. The

wires from the windings are connected through tool wiring to J2-13, J2-14, and J2-15 on

the commutator board. Each motor lead is connected into a pair of FET switches

configured to switch that particular lead to the motor power (V_MOT at J3-1 and J3-2)

or to ground. The top set of switches as shown in schematic 707.55559 (Q3 and Q2) and

the associated drivers are discussed as typical.

FET Q3 can connect the motor lead (MOT_1) to V_MOT. FET Q2 can connect the same

lead to ground. These FET switches are controlled by R-to-D board drive signals

(MOTR_A+ and MOTR_A-) connected to the board through connector J1. Drive voltage

from the resolver board is +15-Vdc when high and ground when low.

To connect MOT_1 lead to V_MOT, FET Q3 must be turned ON. Positive 15-Vdc isapplied to MOT_A+. Note that resistor R1 connects to -15-Vdc. Zener IN4749 drops 24-

Vdc from +15, setting the anode of VR1 and the base of Q1 to -9-Vdc. Resistor R1 is

dropping about 6 V under these conditions. Transistor Q1 draws enough current through

R2 to raise its emitter voltage to about 5.3 V above the -15-Vdc supply lead, pulling in

the process about 1.5 mA through resistor R5. Voltage drop across R5 is about 15-Vdc,

turning ON transistor Q3. The 18-Vdc Zener VR2 is for gate protection. Any voltage

above 7 or 8 across R5 is enough to turn on FET Q3. Drive voltage for Q3 is the same

(or nearly so) for all V_MOT levels from 10- to 200-Vdc.

To turn OFF Q3, the MOT_A+ lead is switched to ground. The -15-Vdc applied to R1 is

not enough to cause 24-Vdc zener to conduct. No voltage is dropped across R1, and Q1

draws no current through R5, leaving Q3 turned OFF. If it is desired to ground the

MOT_1 lead, a +15-Vdc signal is connected to J1-2. This lead is connected directly to

the gate of Q2 through resistor R6, causing the Q2 to turn ON.

Figure 2-18 shows the relationship of the gate-drive waveforms for one pair of switches

and the waveform observed at the collector. The top trace A is of the gate waveform of

the P-FET connected to V_MOT (Q3 in our example). Trace B is of the gate waveform

of the N-FET switching to ground (Q2 in our example). Trace C is of the waveform seen

at the MOT_1 lead. V_MOT is set to 50-Vdc. Note that the gate waveform for the P-FET

(Figure 2-18, trace A) never goes negative simultaneously with positive excursions of the




N-FET drive waveform (Figure 2-18, trace B). The sloped portion of the drain waveform

occurs when there are no transistors turned ON for that particular motor lead.

The spikes on the drain waveform are the result of the magnetic fields collapsing in the

motor. The peak amplitude of the spike is limited to the supply voltage by the parasitic

body diode of the opposite transistor to the one switched off, that is., the P-FET diode

catches the N-FET turnoff spike. This is normal and desirable because the energy of thespike is captured and returned to the power supply, increasing the overall efficiency. The

repetition rate of the drive waveform is related to the motor speed.

Note that the board is perfectly capable of shorting out the V_MOT input to ground if

both J1-1 and J1-2 are simultaneously connected to +15. The drive circuitry on the

resolver board never does this (Figure 2-18, traces A and B), but in tests, ground all

unused inputs on J1 through a 10-k Ω or lower resistor to prevent simultaneous turn-on.

Inspection of the schematic shows the other two motor leads (MOT_2 and MOT_3) to be

connected to similar circuitry as is connected to MOT_1.

Operational amplifier U1 is connected to sample the current sent to the motor through

Q2, Q5, and Q8. The total motor current is the sum of the currents through R7, R14, and

R21. The voltage across each of these current sense resistors is connected through a4990-Ω resistor into the sum junction U1-2. Voltage at U1-6 (C_SENSE) is coupled to

the slow ADC board in the tool to be measured and sent uphole in the telemetry stream.

The voltage at U1-6 is equal to the current drawn in amperes multiplied by -1 (350 mA

of current show as -350 mV at U1-6).

Figure 2-18: Waveforms from a Commutator Board




Compass Board (Drawing 707.55574)The compass board contains circuitry to work with a saturable inductor to produce a

magnetometer and some interface circuitry for an inclinometer. Outputs from the compass board

are directed to ADC circuitry in the DITS CAST-V tool. The magnetometer and inclinometerprovide directional information to the logging software.

Power

Power required for the compass board is provided by the CAST-V electronic package directly

above the directional sub. Voltages required are +15-Vdc only. Current drain is approximately 30

mA from the +15-Vdc input and 20 mA from the -15-Vdc lead.

Saturable Inductor

An external magnetic field (dotted lines in Figure 2-19) applied to the saturating core affects the

saturation of the core, making the core saturate easier on the side where the external flux aids

flux from the drive winding. On the opposite side of the core, where the external flux opposes the

flux from the drive winding, the saturation takes longer. When the saturation takes place on one

side of the coil faster than the other, a high-frequency directional burst of flux is generated. This

flux burst is detected by the voltage it induces in the sense coils. The two sense coils are at 90 to

each other (x- and y-axis). The direction of the high-frequency burst can be calculated from the

amplitude of the voltages from the two sense coils.

Figure 2-19: Saturable Reactor Flux Diagram




The inductor used in the magnetometer circuit has six leads connecting to three coils.

The unmarked terminals on the saturable inductor are the drive windings; the marked

windings are the sense windings. When a square-wave ac drive voltage is connected into

the drive winding through current-limiting source resistance, the current through the

drive winding is similar to that in Figure 2-20, trace C. This waveform was captured by

connecting a storage oscilloscope to TP-1 on the compass board. (The drive waveform is

drawn over the TP-1 signal for reference.) The drive coil supports the entire ac voltage aslong as the core is not saturated, causing little current flow. At the point of saturation, the

drive coil impedance drops drastically, essentially switching the drive signal directly into

R14, resulting in the waveform shown in Figure 2-20, trace C.

Figure 2-20: Analog Waveforms from a Compass Board




Circuitry

Circuitry to drive the saturable inductor coil and measure voltages induced in the sense

coil windings is located on the compass board. Refer to schematic 707.55574 during the

following discussion.

Oscillator-Driver

Chip U3 provides oscillator-driver functions for the magnetometer. Oscillation frequency

is set by resistor R37 (a factory adjust, or FA) and capacitor C16. Normal drive

frequency to the saturable inductor is between 24 and 30 kHz. Output from the chip at

U3-14 is coupled through resistor R42, capacitor C20, and terminal J2-8 to the saturabie

inductor drive winding. R42 is a fuse in case of a short circuit. Capacitor C20 prevents

any average dc current from flowing in the drive winding.

Sense winding signal outputs are amplified and applied through two analog switches to

integrators to get dc output signals. The analog switches U4/A and U4/D are closed only

for the moment that signals are present from the effects of core saturation. To ensure thatthe closure of U4/A and U4/D encompass the moment of saturation of the saturable

inductor, circuitry has been included to control the saturation point. Feedback circuitry

automatically adjusts the point of saturation to correspond to the closing of switches

U4/A and U4/D. Without this circuitry, the magnetometer would have severe drifts with

temperature.

Control of the saturation curve is accomplished by controlling the amplitude of the drive

signal to the saturable inductor. The closing of switch U4/C is synchronous to the drive

waveform’s positive excursion. Closing of switch U4/B is timed to encompass the

moment of core saturation. Closing U4/B occurs when the switch control voltage goes

negative (Figure 2-21, trace C), selecting the portion of the drive waveform (Figure 2-21,

trace D) containing the moment of saturation of the inductor core. Output of U4/C iscoupled by R16 into the operational amplifier integrator circuitry U1/B and C4. U1/B

amplifies the difference between the integrated output voltage and a dc reference voltage

(set by R4 into R3), which corresponds to the desired average dc signal from the output

of the analog switches. U1/B-7 output is coupled to transistor Q1, which adjusts the peak

amplitude of the drive signal to the proper level to center the moment of saturation in the

time window used by the sense amplifiers over a wide temperature range.

Sense Amplifiers

The two sense windings of the saturable inductor provide an output signal similar to that

shown in Figure 2-20, trace A. The peak height of the pulses shown depends on the

strength of the external magnetic field influencing the saturable inductor. The y-axissignal (from J2-3) is amplified by U2, and the x-axis signal (from J2-1) is amplified by

U5. Both amplifiers are adjusted to provide 21 x amplification of the sense winding

signals before coupling into synchronous switches U4/A and U4/D. Output signals from

U4/A and U4/D are similar to those shown in Figure 2-20, trace B. These switches are

controlled by the output of U6/B (pin 9). Output signal polarity depends on direction (the

negative-going pulse shown might be positive).




U6/A and U6/B are one-shots. A negative-going pulse corresponding to transition of the

drive signal is available from U3-4 (OSCOUT, Figure 2-21, trace A). This pulse triggers

U6/B, causing it to begin timing to the predicted time of inductor saturation. At this

moment, U6/B triggers (Figure 2-21, trace B) and holds switches U4/A and U4/D closed

for approximately 5 µs, permitting the amplified sense winding outputs (Figure 2-20,

trace A, is gated to yield Figure 2-20, trace B) to enter R/C filters R26/C6 and R15/C5.

The signal is further amplified by U1/D and U1/C before presentation to the ADCthrough J1-1 and J1-2.

Figure 2-21: Gate Timing versus Saturation Curve

The detection and amplification of the signals have been discussed without reference to

the Fas calibrating the magnetometer circuitry. The exact magnitude of output voltage of

the magnetometer is not required to be calibrated to the magnetic field strength passing

through the saturable inductor. The earth’s magnetic field varies from about 0.24 to 0.7gauss. The output voltage from the magnetometer with the approximate values indicated

in the setup procedure is approximately 1.5-Vdc in a 0.45-gauss field. As long as the

peak voltage from the y-axis of the magnetometer is equal to the peak value of the x-

axis, the absolute amplitudes are not important. Only the ratio between the amplitudes is

important.




Measurement Calculations

If the saturable inductor is rotated around its axis, output from the y-axis circuitry is

shifted from the x-axis output by 90°. As the inductor is rotated (by rotating the

directional sub in a test fixture), the x-axis voltage is at a maximum when the DITSbutton is pointed north. At this time, the y-axis voltage will be at a minimum. With the

DITS button pointed northwest, both voltages are the same. With the DITS button

pointed east, the y-axis voltage is at a maximum, and the x-axis voltage is at a minimum.

The voltages from these detectors may be thought of as sine and cosine waves relating to

the rotation of the inductor. The peak amplitude of the sine and cosine waveforms is

determined by the magnetic field strength. The equation below indicates how the

voltages are used by the tool to indicate direction.

where

A = peak amplitude of MAGX or MAGY

• A*Cos(θ) = MAGX = Signal at J1-25 (upper DITS connector)

• A*Sin(θ) = MAGY = Signal at J1-24 (upper DITS connector)

θ = angle measured from magnetic north

φ = rotator to place the angle in the right quadrant

The operator 4 is obtained by examination of the polarity of the voltages seen at the x-

axis and y-axis output. For the magnetometer circuitry we are discussing, is determined

as follows:

• If MAGX is positive,

• and MAGY is positive, then φ = 0

• and MAGY is negative, then φ = 360

• If MAGX is negative,

• and MAGY is negative, then φ = 180

• and MAGY is positive, then φ = 180

Factory Adjusts

The resistors adjusting the amplifiers are adjusted in a particular sequence. This sequence

is described below;

1. Resistor R37 is used to set the operating frequency to the saturable inductor.

2. Resistor R19 is used to set the positive and negative swings of the x-axis sense

circuitry to the same peak magnitude.

3. Resistor R20 is used to set the positive and negative swings of the y-axis sense

circuitry to the same peak magnitude.




4. Resistor R18 is usually kept at the same value (10 k Ω). R18 can be changed to adjust

the y-axis peak amplitude to a new value. However, changing R18 requires that the

entire setup be repeated with the new resistor in place.

5. Resistor R1 1 is used to match the peak amplitude of the x-axis output to that of the

y-axis output.

6. Resistor R1 is used to rotate the x-axis signal to get exactly a 90° phase shift fromthe y-axis signal. Always set this resistor equal to R2 during the early stages of the

setup.

7. Potentiometer R8 allows the peak amplitude of the inclinometer y-axis signal to be

set to 4.00-Vdc.

8. Potentiometer R10 allows the peak amplitude of the inclinometer x-axis signal to be

set to 4.00-Vdc.

Data Acquisition Board (Drawing 707.41002)

The data acquisition board for the CAST-V tool consists of an 8-bit flash ADC,amplifiers to optimize the input voltage level to the ADC, and other parts to provide

support. Gain of the amplifiers can be adjusted from 1x to 181x in 1.414x increments

(1.414 = √2 =3.01 dB). Inputs to the board are signal- and digital-control signals.

Outputs from the board are a digital representation of the analog signal, with

measurements on the input signal taken at 200-ns intervals.

Refer to schematic 707.41000 during the following discussion. A circuit description of

the Data Acquisition Board components follows.

Gain Control

Quad-latch U8 is driven by the tool digital electronics to select the gain provided for theADC. Four gain controlled amplifiers (V1, U3, U4, and U6) are cascaded to provide 16

gain steps of 1.414x each. Each gain-controlled amplifier has analog switches connected

to set the amplifier to either unity gain or a greater gain. The 16x stage (U1) with its

controlling analog switch U2 is discussed as typical.

The input signal for U1 is from the preamplifier/fire board through connector J1. The

gain of U1 is controlled by setting the amount of negative feedback provided. To get

unity gain, switch U2/A (pins 1, 2, and 3) connects U1 output (pin 6) to the U1 negative

input (pin 2). To get 16x amplification, switch U2/A is opened, and U2/B is closed,

causing the junction of R3 and R4 to be connected to U1-2. Gain is nearly equal to (R3+

R4) / R4, x15.87. Resistor R38 trims the gain to exactly 16.

Analog switches U2/A and U2/B are controlled by one section of quad-latch U8.

Instructions from the tool processor are connected to pin J2-3 to turn the 16x stage ON or

OFF. This instruction is placed on lead J2-3 by the processor and latched into U8 by a

positive strobe applied to J2-8. If 0 is on J2-3 at the moment of latch U8-2 reaches 0,and

U8-3 reaches 1 (+5-Vdc). The analog switch control voltage requires a 0 to close and a 1

to open. Thus, U2/B is closed; U2/A is opened (note that U8 provides a latched,

noninverted output on pin 2, and a latched inverted output on pin 3). U2/B connects the

R3/R4 junction to the negative input of U1, and the gain reaches 16x.




Amplifier stages U3, U4, and U6 work in similar manner. Each stage gives either unity

gain or a higher gain set by the resistive divider in the negative feedback path.

In the last stage of amplification, U7 provides a signai inversion and an offset voltage.

The offset voltage is provided to allow the 4-V peak-to-peak bipolar ac signal from the

U1, U3, U4, and U6 amplifier to appear as a 4-V single polarity signal to the ADC.

(When the ac signal is at a -2-V peak, the ADC is presented with a +4-V peak. When theamplifier output is at +2 V, the ADC measures 0 V.) The offset voltage is generated by

dividing the ADC reference voltage (4-Vdc) by 2 and applying the voltage to the positive

input of U7 (pin 3). The divider is formed by resistors R18 and R20. Actual division is

set slightly off one half (R18 is 19.6Ωk instead of 20 k Ω) to keep the ADC MSB from

oscillating too much with zero input signal.

Reference Voltage

Reference voltage for the ADC is provided by U9, reference zener VR1 and associated

circuitry. Zener VR1 provides a 6.4-Vdc temperature-compensated voltage amplified by

U9/A to get a 10-Vdc output at U9-1. The 10-Vdc is divided down to 4-Vdc by resistors

R26 and R34 and buffered by U9/B. The buffered 4-Vdc is applied to the REF input to

the ADC (U10-17) and to divider (R18/R20), which provides the 2-Vdc of offset to the

signal input to the ADC. FA resistor R31 allows the 4-Vdc to be trimmed to exactness. If

the manufacture’s tolerance on the zener is excessive, R24 may have to be adjusted as

well. The zener VR1 is chosen for temperature stability, not initial precision.

ADC

The MP7684 ADC chosen for this tool takes an 8-bit measurement each time the clock

lead goes negative. The clock applied to the MP7684 (U10-1) is 5 MHz, resulting in a

measurement every 200 ns.

Chips U11 and U12 buffer the output of the ADC before presenting it to the other

circuitry in the tool.

Preamplifier/Fire Board (Drawing 707.55668)

The preamplifier/fire board for the CAST-V provides 400-V peak pulses which drive the

mud-cell and scanner transducer. Interface circuitry is also provided to condition the

recovered signals.

The 400-V peak pulse is set to a 1.2-µs pulse width. After the transducer is fired, the

drive circuitry is turned off, and the same transducer is used to receive the reflected

signal. The signal is further conditioned by the data acquisition board before presentationto the ADC. Overall gain of the entire signal path from transducer to ADC is adjusted to

optimize the signal level to the ADC input range. The timing of the firing of the

transducer is controlled by the acquisition control and DSP board.




Generation Of The Ultrasonic Pulse

Refer to schematic 707.55668. There are two fire circuits on the preamplifier/fire board.

One circuit consists of Q5 and associated circuitry used for the mud-cell, and the other

consists of Q4 and associated circuitry used for the rotating transducer. Q4 andassociated parts are discussed as typical.

U1 EPLD contains gates arranged to take a pulse at U1-2 (TP-2) and gate it to U1-9 or

U1-10. The output at U1-10 is used to fire the rotating transducer, and the output at U1-9

is used to fire the mud-cell transducer. Selection of which transducer to be fired is

controlled by voltage level on U1-3 (TP-1). The U1-3 signal is a positive-going pulse

used to switch the mud-cell to the signal path for enough time to get an entire waveform.

The mud-cell is read only once every 10 scans. Input signals controlling the firing and

selection are received from the DSP and acquisition control board.

Assume that a typical, positive-going, 1.2-µs, 5-V fire pulse is coupled into U1-2. The

pulse is inverted and gated to U1-10. U1-10 is connected into U4, pins 5 and 8. Device

U4 functions as a high-current buffer and level shifter. The output from U4, pins 10 and11, is a negative-going 15-Vdc pulse coupled into the gate of Q4 by parallel connected

capacitors C21, C22, and C23. Q4 turns ON, connecting +400-Vdc and charged

capacitor C34 to the transducer (through connector J2) for the duration of the pulse. After

Q4 turns off, C34 recharges to +400-V through resistor R24, and the charge present in

the transducer (electrically similar to a capacitor) is drained by resistor R40 and the

network R34, R35, R32, R31, and associated parts in HY1's input circuitry. The resulting

pulse shape is shown in Figure 2-22.




Figure 2-22: Fire-Pulse

Transistor Q5 and associated parts fire the mud-cell. Electrically, they function in a

similar manner to Q4. When the mud-cell is to be fired, the level seen at TP1 (U1-3)

switches to +5 V for the time required to fire the mud-cell and recover the sonic signal.

Positive 5-Vdc on U1-3 causes the fire pulse to exit U1 through pin 9 into U4 pins 1 and

3. Output from U4-12 and U4-13 couples to Q5 through C18, C19, and C20 and fires the

mud-cell transducer connected to J1.

Recovering the Return Signal

The rotating transducer signals are coupled to the amplifiers and signal-conditioningcircuits through input resistors R34, R35, R31, and R32 from the transducer connection

at J2. The hybrid HY1 can be set up to provide a loss of 0.0635x (-24 dB), unity gain, or

a gain of 15.86x (+24 dB). The hybrid also contains the gating circuitry that switches the

return sonic signal to the measuring circuitry.

Gating of the sonic signal is controlled by an input to U1-6. This signal goes negative

while the fire pulse is generated, and while the ring-down effects from the fire pulse are

present. The signal can be adjusted in length by the software for the tool, but typically a

20-µs, negative-going pulse with the leading edge synchronized to the fire pulse is




observed at U1-6. The inverted gate pulse exits U1 on pin 20, enters HY1 on pin 27, and

controls an analog switch in the signal path.

Control signals from the tool processor set the various gains according to Table 2-3.:

Table 2-3: Input Select and First-Stage Gain Control

HY1-31 HY1-32 Result

0 0 0-dB gain, mud-cell unity gain

0 1 -24-dB gain, mud-cell 0.06345x

1 0 0-dB gain, rotating transducer unit gain

1 1 -24-dB gain, rotating transducer 0.06345x

A second-stage amppifier in the hybrid (in the lower right of the hybrid in schematic

707.55668) provides unity gain or +24-dB gain according to the Table 2-4.

Table 2-4: Second-Stage Gain Control

HY1-28 Result

1 0 dB unity gain

0 +24 dB 15.86x

Assume that the tool processor has setup the preamplifier/fire board to provide high gain

(+24 dB) on the rotating transducer. To get +24 dB, the first-stage gain is set at unity,

and the second-stage amplifier gain is set to 15.86x (+24 dB). Digitally, the setup is as

follows:

1. HY1-28 is set to 0.



The two- to four-decoder in HY1 with the above input levels connects the signal path

from the unity gain amplifier (third amplifier on the left in the HY1 schematic

707.55668) to HY1-36. The signal from HY1-36 is coupled back into the hybrid to the

second-stage amplifier through HY1-25.

The second amplifier stage in the hybrid (circuitry at the lower right of the hybrid in

schematic 707.55668) is programmed by setting HY1-28 to 0-Vdc. Gain provided with

HY1-28 at 0 V is +24 dB (15.86x). The output signal from HY1-21 is routed to Q3 by

board wiring.

Q3 is an active glitch suppressor to help remove undesirable switch glitches from the

signal. From Q3, the signal passes through a high-pass filter consisting of U5 and

associated parts to a low-pass filter consisting of U3 and associated parts to connector J3,

the output signal connector of the board. Response characteristics of the board, including

and primarily dependent on the filter characteristics, are shown in Figure 2-23.




Figure 2-23: Gain and Frequency Response Curves

If the hybrid is programmed to provide unity gain, the amplifier in the lower left of the

hybrid is programmed to 1x gain. All other parts of the signal path are the same as the

previously discussed +24-dB setup. Digital setup is as follows:

• HY1-28 is set to 1 (sets second-stage gain to unity).

• HY1-31 is set to 1 (with HY1-32, sets input gain to unity).

• HY1-32 is set to 0 (with HY1-31, sets input gain to unity).

To apply a gain of -24 dB (0.06345x) to the rotating transducer signal, the second-stage

amplifier is programmed to 1x; the input amplifier is switched from the amplifier with

the 5-k Ω feedback resistor to the amplifier with the 500-Q feedback resistor. Digital

setup is as follows:




• HY1-28 is set to 1 (sets second-stage gain to unity).

• HY1-31 is set to 1 (with HY1-32, sets input gain to -24 dB).

• HY1-32 is set to I (with HY1-32, sets input gain to -24 dB).

For a -24-dB gain, the signai from J2 enters the hybrid through R32 and R31 into HY1-

10. The gain of the first-stage is R32 (3400 Ω) plus R31 (3480 Ω) plus 1000 Ω (inside

hybrid) divided into 500 Ω (the feedback resistor inside hybrid). The gain would be

0.06345, or -24 dB. Note that the unity gain input amplifier and the -24-dB input

amplifier are both always connected to the transducer.

Auxiliary Circuitry

Transistors Q1 and Q2 and dual amplifier U2 are connected as regulators to provide +7-

Vdc to power HY1. Reference voltage for the regulators is provided by zener VR1. U2/A

is adjusted to amplify the zener voltage to +7-Vdc by setting the size of FA resistor R7.

Q1 is mounted to a heat sink to help absorb the power dissipated during regulation.

U2/B is connected as an inverting amplifier, causing Q2 to turn on until the current

through R5 matches the current through R6. FA resistor R6 is set to cause this current

match when the output of Q2 is at -7-Vdc. Q2 is mounted to a heat sink to absorb the

dissipated power.

CAST-V Power Circuitry

This section discusses the powering of the CAST-V tool (assembly 707.50606 and

associated chassis mounted components), including operation of the following circuits:

• power interface to the tool bus

• inverter and control circuit for local +5-, +15-, -15-, and 400-Vdc power supplies

• motor voltage

Circuit Description

Power enters the tool through pins 13, 14, 16, and 19 (refer to the block diagram in

Figure 2-24). These pins correspond to cable conductors as shown in Table 2-5.

Table 2-5: CAST-V Power Conductor-to-Pin Identification

Conductor Pin Color

1 13 BRN

2 14 ORG

4 16 YEL

5 19 BLU




60-Hz 120-Vac power for the instrument section is fed into large chassis-mounted

transformer T1, with 120-Vac applied across the BRN and ORG leads and across the

YEL and BLU leads. The 60-Hz power is phased and balanced so that the two center taps

(RED and GRN) on T1 do not show voltage when ac power is applied. Application of ac

power in this manner is W5 mode. The surface system can also feed dc voltage down the

center taps of conductors 1 and 2 versus conductors 4 and 5. Application of power in this

manner is W2 mode. Power applied in W2 mode is used to operate the scanner motor of the CAST-V. The operation of the instrument power circuitry running from the W5 mode

is discussed first, followed by a discussion of the operation of the W2 mode motor

power.

Instrument Power

Instrument power is obtained from the W5 mode power supplied by the wireline. A

chassis-mounted transformer and two printed circuit boards (707.50603, preregulator,

and 707.50600, inverter) convert the W5 power into voltages appropriate for tool

operation.

60-Hz power at approximately 120-Vrms is applied to windings W1, W2, W3, and W4.

The voltage is coupled by the transformer to W5 (141-Vrms nominal) and to W6 (27.6-

Vrms nominal). Windings W6 and W5 are connected series opposing to get an output

voltage of (141 - 28) or 113-Vrms which is rectified and fed to the DC-DC inverter,

which develops the tool operating voltages. T1 winding W7 provides the 27 V used for

starting the inverter.

The normal DITS operating range for instrument power is 120 V +/-15%, which means

from 102 to 138 V. Output from T1 ranges from 86 to 117-Vrms at the input of the

bridge rectifier.

The 86- to 117-Vac from the transformers is rectified by a CR1-CR4 on the preregulator

board and filtered by inductor chassis-mounted L1 and C2 before passing through

transistor Q1 to the inverter. Transistor Q1 is controlled by an error amplifier sensing the

+5 V output. The 5-Vdc output is the only low-voltage source on the tool in a tightly

controlled regulator circuit. The +15- and -15-V output of the inverter are much more

likely to drift with temperature and load. The 400-Vdc that fires the transducer is also

tightly regulated.




Figure 2-24: CAST_V Power Circuitry Block Diagram




As power is applied to the chassis-mounted T1 several things happen:

1. When voltage in winding W7 gets high enough, the inverter starts.

2. The inverter, drawing power from pass transistor Q1 begins generating voltages at

the various outputs.

3. Regulator circuitry senses the increasing voltage from the 5-Vdc inverter output andbegins regulating the inverter input voltage through Ql to hold the 5-Vdc output

steady.

4. A step-up transformer, running from ac coupled from the main inverter circuitry,

generates 460-Vac which is rectified, filtered, and regulated to 400-Vdc for firing the

transducer.

Startup

Refer to schematic 707.50600. AC voltage from winding W7 connects to J1-1 and J1-9.

Rectified output from W7 passing through R5 and R4 turns on transistor Q1. Q1 emitter

increases voltage until the turn-on voltage (10 V) of zener CR3 is reached. Voltage is fedthrough CR5 to provide 9 V on the power leads of U1. U1 begins oscillating, feeding

square-wave drive voltage into the gates of Q2 and Q3. The startup circuit disconnects

whenever the voltage at the cathode of CR6 becomes higher than the 9 V supplied by the

startup circuitry. After startup, the power to operate U1 comes through CR6, and CR5 is

reverse biased.

Inverter

The inverter consists of Ul, Q2, Q3, T1, and associated parts. Chip U1 is a general-

purpose oscillator/FET driver designed for use in switching regulators. U1 is used to

provide square-wave drive voltage at high-current for transistors Q2 and Q3. Oscillation

frequency is set by R7 and C3. R6 provides a dead time (neither Q2 or Q3 conducting) tomake the turn-on and turnoff times of FETs Q2 and Q3 less critical. Resistors R14 and

R15 prevent parasitic oscillations by FETs Q2 and Q3.

Q2 and Q3 begin switching power through transformer T1, generating ac voltage at the

output windings of board-mounted T1. The voltages are rectified and coupled to filter

networks consisting of L1, L2, L3, and their associated capacitors. These networks

remove inverter noise from the output voltages.

The TSC15C25 device used for U1 is designed for use in a wide variety of switching

regulator circuits, and much of the internal circuitry is not used. Some of the circuitry is

used as a current limiter, however, to limit the supply dissipation if a short occurs on one

of the output voltages. The operation of this limiting circuitry is discussed next.

Current drawn by the inverter is sensed by a 0.5-Q resistor (R16) between the source lead

of FETs Q2 and Q3 and ground. As current is drawn by the tool, the voltage at the

junction of R16/R11 increases at 2 V/A. This voltage modifies the voltage at the

negative input (U1-1) of an internal operational amplifier in U1. If the voltage at the

negative input passes a fixed reference voltage (1.25-Vdc) at the positive input (U1-2),

the supply begins current limiting by causing the ON times of Q2 and Q3 to drop. This

current limiting occurs at about 400 mA of tool current. Normal voltage across R16 is

about 90 mV.




Note Experience with this circuit has shown that prolonged short circuits on the low-

voltage outputs cause failure in the input filter capacitors for the shorted output.

The operating current for the current limiter voltage reference (Zener CR2) is supplied by

diode CR1 and resistor R1. CR1 is a 1-mA current diode; it provides 1-mA of operating

current for CR2 over a wide range of input voltage variation.

Diodes CR7 and CR8 catch the spikes generated by the power transformer at the moment

the FETs are switched. Energy in the spike is fed back into the power input to the supply

through R17.

Preregulator

The preregulator board contains the control circuitry for the inverter, the rectifiers for the

60-Hz input power, and the circuitry to develop the 400-Vdc used to fire the transducer.

Diodes CR1 through CR4 (refer to schematic 707.50603 and to Figure 2-24, block

diagram) are used to rectify the output voltage from chassis mounted T1. The rectified

and filtered voltage is connected to the Q1 chassis-mounted drain. This transistor is

turned on by current flowing through R1 and R3 into the gate. The output of the FET

(“82 V Regulated” on schematic 707.50603) is coupled to the inverter for conversion to

lower voltages as required for the tool electronics. Off-board mounted CR17 is a 91-V

device used to prevent excessive overvoltage to the tool electronics if the preregulator

fails.

Control of pass transistor Q1 is accomplished by comparing the +5-Vdc output of the

supply to a zener-stabilized voltage and adjusting the conduction of Q1 to provide just

enough power for 5 V output.

Reference zener CR11, a 6.4-Vdc device, provides a low-drift 6.4-Vdc source. The

voltage from this zener is amplified to get a 10-V output. R34 is used as an FA to set the

output of U1 to exactly 10-Vdc. This 10-Vdc is the reference for all the output voltages

of the supply.

10-Vdc is fed into the input of U1/A through a voltage divider consisting of R12, R13,

and R10 into R11. After adjustment of R13, the final voltage at the R10-R11 junction

(the positive input of U1/A) is +5-Vdc. Negative input U1/A is connected to the +5-Vdc

output of the supply through R9. When the reference voltage is larger in magnitude than

the sensed output voltage at R9, the operational amplifier output goes positive, turning

Q2 OFF. As Q2 is turned OFF, Q1 is turned ON by resistors R1 and R3, raising the

input voltage to the inverter and all output voltages from the inverter. When the

5-Vdc output of the inverter matches the 5-Vdc reference voltage, the operational

amplifier adjusts the conduction of Q1 through Q2 to exactly hold that level of

conduction to maintain the 5-Vdc out. Components R8, C5, C4, R6, and C3 are used toprevent the amplifier from oscillating.

400-Vdc Circuitry

When the inverter and preregulator are functioning correctly, the ac voltage swing at all

points on the inverter transformer is predictable. An ac signal is taken from the secondary

of the main power transformer and connected to step-up transformer T1 (not the 60-Hz

T1 but rather a small transformer shown on the preregulator schematic). T1 provides a




large step up in voltage. The output of T1 (near 465-Vac) is rectified by CR13-16,

filtered by L1 and the components shown clustered around L1, and applied through

resistor R32 to a shunt regulator circuit consisting of Q3, Q4, U1, and associated parts.

Resistors R21 and R20 cut down the dissipation required in Q3. Q3 gate is grounded and

control of the FET is accomplished by lowering the drain of Q3 by Q4 enough below

ground to cause Q3’s grounded gate to turn on the FET. Control of Q4 gate isaccomplished by a section of quad amplifier U1. The 10-Vdc reference voltage is

connected to the positive input (pin 12) of the operational amplifier. The 400-Vdc output

is connected to a voltage divider set to give 10 volts at the negative input (pin 13) of the

amplifier. If the output voltage gets too high, the output of the amplifier goes negative,

turning on Q4, which turns on Q3, which loads down the output voltage until the divider

provides exactly 10-Vdc at pin 13.

Motor Voltage

Refer to Figure 2-24, the block diagram. The RED and GRN wires from the center taps

of the instrument power transformer are the source of motor power in the tool. Two large

chassis-mounted 150-pF capacitors, C1 and C4, are connected across motor power to act

as reservoirs to handle the surge currents of the motor commutation circuits. The GRN

wire, corresponding to the center tap of J1-16 and J1-19, is connected to ground in the

tool and is the negative power input lead. (Note that this connects armor in parallel with

lines 4 and 5 for W2 power.) The RED wire, connected to C1+ and C4+, is the positive

power input lead corresponding to the center tap of J1-13 and J1-14. Motor voltage and

current are monitored by circuitry in the commutator and slow ADC boards.

R-to-D Board (Drawing 707.55561)

The R-to-D board contains circuitry to control commutation for the scanner motor of the

CAST-V tool. Commutation is the act of switching current through field windings tocause the rotor of the motor to rotate efficiently. The actual switching of the drive

voltage to the motor is accomplished by the commutator board (707.55559). The R-to-D

hoard provides control signals to the commutator board. The R-to-D board also provides

circuitry to set the pattern of the sonic pulses as the head rotates.

Circuit Description

Refer to schematic 707.55561 during the following discussion. It is necessary to know

the position of the rotor of the motor to select the correct way to of energize the motor

windings to get rotation. The position of the rotor is sensed by a resolver fastened to the

shaft coming out of the motor. There are three windings on the resolver, a rotating drivewinding and two signal-output windings. The resolver drive signal REFA can be seen at

J2-4. REFA is obtained from a sine wave oscillator on the R-to-D board. The resolver is

wound to provide a sine- and cosine-output signal which is a function of the shaft

rotation. The two output signals from the transformer are connected to J2-7 and J2-5 of

the R-to-D board.




The signal to drive the resolver is provided by a sine wave oscillator made with U8, U7,

Q1, Q2, and associated parts. A 5000-Hz (approximate, any frequency in the 4500- to 6-

kHz range) sine wave appears at the emitters of Q1 and Q2. Oscillation results from

positive feedback from Q1/Q2 emitters through R3 into low-pass active filter U8. U7 is

also connected as a low-pass filter. The amplitude of the oscillation is maintained by the

clipping of CR1 and CR2. Frequency of oscillation is determined by the phase shift and

amplitude characteristics of the low-pass filter elements. The distortion created by theclipping of the diodes is removed by the low-pass filtering of U8 and U7. An oscillator

of this type is sensitive to component values. Take care in selecting components for

repair.

The resolver transformer drive waveform (REFA) is shown in Figure 2-25.

Figure 2-25: Waveforms from the Oscillator and Resolver Transformer

On Figure 2-25, the COS waveform was taken at the same time as the drive waveform.The sine waveform is very similar to the COS. At any given moment, the COS

waveform is almost in phase or almost out of phase with REFA.

The amplitude of the COS waveform varies as the motor rotates, as is shown in Figure 2-

26.




Figure 2-28: Amplitude Modulation Resulting from Rotation of the Scanner

At the points where the COS waveform seems to go to zero, the phase of the 5000 Hzinverts. The sine input (U1-7) is at zero at the time the transducer face points at the DITS

button. At that moment, the COS input to U1 goes to maximum amplitude. Slightly

clockwise of DITS, the sine waveform is in phase with REFA. Slightly counter-

clockwise of DITS the sine waveform is out of phase with REFA.

The 5000-Hz sine wave is connected to the drive winding on the resolver through J2-4.

The 5000-Hz signal is also connected to the REF input of U1 for phase reference in

determining the orientation of the resolver.

The inner workings of U1 (AD2SSO) are not discussed here, its purpose is to convert the

sine and cosine analog signals into a digital number proportional to the current rotor

shaft position. The resistor-capacitor networks connected to U1-2 an U1-3 connect an ac

error signal (U1-3) into an internal phase-locked loop. The resistor-capacitor networks onU1-37, U1-39, U1-38, and Ul-40 shape the response curve of error amplifiers within the

device. Pins with signals of interest are the BUSY (U1-33) and RCLK (U 1-35). RCLK

provides a pulse whenever the BIT outputs are all 0, which happens only once per

revolution. BUSY (Ul-33) is low when the data lines (BITO - BIT15) are valid.

Data lines B15 through B6 are connected to the address lines of EPROM U2. U2 is

programmed to provide drive signals to operate the FET switches on the commutator

board. These signals appear on U2 output leads Q1 through Q6. As the digital output

from U1 changes to reflect the position of the rotor of the motor, programming in U2




selects the appropriate commutator board FET switches to operate. As the rotation takes

place, the START lead (Q8, U2-19) is programmed to provide a pulse whenever the rotor

is at the appropriate place for a sonic pulse. Three of U2’s address lines (RATE0 at U2-

21, RATE1 at U2-23, and RATE2 at U2-2) are connected to the tool’s microprocessor

through U11, J1-6,

J1-13, and J1-12. The RATE lines allow the microprocessor to change the pattern of thesonic pulses. Another output provides a pulse (TACH/REF) once per revolution for

synchronizing purposes.

U3 is a latched buffer controlled by U4-14 that ensures that output signals are not

enabled during the moments when the EPROM output is changing. The latch signal from

U4-14 corresponds to U1-33, the BUSY signal from the AD2SSO chip. An input into U4

from the microprocessor provides an additional latch signal to ensure that the motor has a

valid pattern at startup.

U9 and U10 are level shifters to raise the digital signal levels to 15-Vdc which is more

appropriate to the commutator board input circuitry. Enable lines U9-2 and U10-2 are

controlled by a flip-flop in U4 that is SET or RESET by a pulse on SEL0, qualified by

the state of IOWR or IORD. Whenever IOWR and SEL0 are simultaneously LOW, theMOTSW lead of U4 goes high, turning the motor ON. When IORD and SEL0 are

simultaneously LOW, the motor turns OFF.

Integrated circuits U5 and U6 provide a serial output (POS DAT at J1-10) reflecting the

position of the resolver. Readings of U6 and U5 are controlled by the tool

microprocessor. Loading of U5 and U6 is done by the buffered BUSY output of the

AD2S80. Currently, the output of U5 and U6 is not used.

Slow ADC Board (707.55587)

The slow ADC Board is designed to function as an eight-input voltmeter. The slow ADC

is presently connected to measure the following signals:

• motor voltage

• motor current

• magnetometer x-axis

• magnetometer y-axis

• inclinometer x-axis

• inclinometer y-axis

• inclinometer temperature

• Head ID is not currently used

The slow ADC board sends one voltmeter reading to the microprocessor each time it is

strobed by the processor. Data are sent to the serial port of the V40 microprocessor as 2

bytes of data, where 3 bits are a tag for the location of the reading and 13 bits are the

reading from the ADC (12 bits of magnitude and 1 as a sign). Each transmitted reading is

actually the last done by the ADC. If the ADC is strobed when the input selector is set to

read the Magnetometer x-axis, you get the motor current reading. The Magnetometer x-

axis reading comes from the next strobe.




Circuit Description

A circuit description of the slow ADC board components follows.

Analog Circuitry

Analog circuitry consists of the following parts:

• reference circuitry for ADC

• regulator to provide -5-Vdc to the ADC

• analog switch to select the measurement

• buffer amplifier

Refer to schematic 707.55587 during the following discussion.

Reference Voltage

Reference voltage (4.5-Vdc) for the ADC U4 is provided by LT1019-4.5 (U3). Outputfrom U3 is coupled to the ADC through capacitor bypass circuitry C16, C17, and R7.

LT1019 output drift directly affects the reading of the ADC. If the LT1019 drifts down in

voltage, the reading of the ADC drifts up by the same percentage. Typical drift of the

LT1019 is about 0.3% at 175°C.

Negative 5-Vdc

The CS5014 requires -5-Vdc at about 14 mA as one of its supply voltages. Because this

voltage is not a normal output of the CAST-V tool power supply, it was provided to the

CS5014 by a local regulator from the -15-Vdc provided by the CAST-V tool power

supply. Negative 15-Vdc enters the regulator through R8, where some of the waste

power is absorbed. Transistor Q1 is controlled by U2/B. U2/B’s positive input (pin 5) isgrounded; all control is through the negative input at pin 6. Approximately 99.3 µA of

current is fed from the+4.5-Vdc regulator through R6 into U2-6, causing the U2-7 output

to go negative, bringing the base of Q1 negative until the Q1 emitter pulls enough

current through R9 to exactly counterbalance the current through R6. The operational

amplifier adjusts its output voltage to maintain the negative input at exactly the same

voltage as the positive input. When the amplifier is working correctly, U2-5 and U2-6 are

at the same voltage. This condition occurs when emitter Q1 is at -5-Vdc.

Input Selector

Analog switch U1 is connected to multiplex eight inputs to one output. The various input

voltages to be measured are divided by resistor networks (R1 into R2 is typical) to get avoltage in the 0- to 5.0-volt range. Each input resistor network is coupled to a 1-µF

capacitor, which provides stability to the voltage reading at the moment the measurement

circuit is connected. If the measurement is of a voltage of absolute magnitude below

5.0-Vdc, the input network does not have a divider resistor to ground. The voltage

selected by the switch appears at U1-8 to be coupled to buffer input U2-3. Selection of

which input to measure is controlled by EPLD counter circuitry (U11/B) coupled to U1

address lines ADR0, ADR1, and ADR2.




Buffer

Amplifier U2-A is wired as a unity gain buffer. Resistor-capacitor network R4/C15 does

not affect the gain but does provide some input bias current compensation for U2-A.

Output from U2-1 is coupled through R10 into R11 and the ADC. The voltage divider

action of the two resistors raises the 4.5-V measurement range of the ADC to 5 V.

Diodes CR1 and CR2 prevent the ADC from receiving a voltage significantly higherthan the ADC operating voltages.

Digital Circuitry

The slow ADC board is designed to transmit a measurement to the CAST-V

microprocessor board whenever strobed by the processor. When this strobe occurs,

several things happen:

1. The previous measurement value and location is latched into a shift register.

2. The ADC switches from self-calibration mode to measure mode.

3. The ADC latches a new analog value to be measured.4. The new analog value is measured by the ADC.

5. The previous measurement is clocked out to the microprocessor at 9760 baud.

6. The ADC is put into self-calibration mode, in which it remains until the next strobe.

Since everything happens as a result of a strobe, processing of the strobe is discussed

first.

Strobe

A negative-going strobe is applied to J1-13 (SPARE0). The strobe is qualified by the

IOWR signal from the microprocessor at J1-16. Qualification is accomplished by U11/S,U11/U, and U11/F in the EPLD U11. The strobe applied through J1-13 originates at the

microprocessor board. Qualification means that the strobe line must go negative at the

same time as the IOWR line before the ADC begins a measurement. The qualified strobe

connects to U5-1, U6-1, and U7-1, and the three shift registers that clock out the 2 bytes

of data to the microprocessor. The strobe causes the shift registers to latch the last

measurement held at the output of the ADC. The strobe also clears several flip-flops in

the EPLD U11 and preloads U8 in preparation for the transmission of the measurement

to the processor.

Counters

Preloading U8 sets the CO/ZD output of U8 to 1, allowing counter U10 to begincounting. The RCO output of U10 is used to enable U11/D. The clock for U11-D is the

same as U10, and U11/D may be regarded as an extension of U10, making a 5-bit

counter out of a 4-bit counter. Output from U11/D times the shift rate of U5, U6, and U7.

Each shift clock is counted by U8. When 24 shift clocks occur, U8-14 goes low, which

stops the counting of U10 until the next strobe from the tool processor. The shift clocks

coupled to the shift register occur at 9760 Hz.

Counter U11-B in the EPLD counts once for each measurement cycle. Its outputs are

directed to the address lines of U1 to select the channel to be measured. The counter




outputs feed shift register U5-4, U5-3, and U5-14 simultaneously. Thus, the strobe pulse

that loads the shift registers with the ADC reading also loads a tag about where the

measurement was made. The first three data bits shifted out of the shift register are the

location of the reading.

EPLDThe remainder of the parts in U11 not already discussed are used to provide timing

margins for the signals used on the assembly. Flip-flop U11/R only allows U11/L and

U11/M to function after a delay time set by the connection to counter output U9-12. Flip-

flop U11-L and U11/M provides a signai to latch the next analog voltage into the ADC

after it has recovered from the transition from calibration to measurement (Figure 2-27).

Some parts (U11/Y, U11/X, U11/2, and U11/AA) are used to gate a monitor program

and ADC into the V40 board. Gating is controlled by U8-14. (The monitor program is

only used in the design phase of the tool and is not available to the field.) The ADC has

uncontested access to the V40 board whenever a measurement is transmitted.

Figure 2-27: Timing Relationships of STROBE, CAL, and HOLDNOT




Internal Calibration

The CS5014 ADC has an internal calibration routine built into the chip. This calibration

routine begins whenever the CAL input (U4-35) is high. On this board, the ADC is idle

for most of the time between strobes from the microprocessor. The CO/ZD output of U8

is low during this idle time. The CO/ZD output from U8-14 is inverted by U11/H andconnected to the CAL input of the ADC, thus causing the chip to self-calibrate during the

time between measurements.

RS-232 Data Output

Data Output

The RS-232 format requires that data be produced with a plus and minus voltage swing.

The data stream produced by this board has the same arrangement of ones and zeros but

uses a 0- to 5-volt, logic level signal format instead of the bipolar RS-232 format.

The slow ADC card uses three shift registers, US, U6, and U7, to generate the pseudo-

RS-232 signai. The three chips are daisy-chained together by connections from U7-9 to

U6-10 and from U6-9 to U5-10. The U5-9 output is connected to U11-20. EPLD parts

U11-Y, U11-X, U11-Z, and U11-AA are connected to gate the slow ADC into the V40

processor after a measurement has been made and to allow a monitor program to

communicate with the V40 when the ADC is idle. Final output to the V40

microprocessor is from U11-16.

By examination of inputs to the shift registers, the sequence of the bits transmitted can be

seen and are shown in Table 2-6.

Table 2-8: Sequence of Bits Transmitted

Bit No. Device Pin Bit Function

1 U5-6 STOP BIT always high

2 U5-5 START BIT always low

3 U5-4 ADR0 LSB measurement address

4 U5-3 ADR1

5 U5-14 ADR2 MSB measurement address

6 U5-13 DB3 LSB measurement address

7 U5-12 DB4

8 U5-11 DB5

9 U6-6 DB6

10 U6-5 DB7






Table 2-6: Sequence of Bits Transmitted (concluded)

Bit No. Device Pin Bit Function



15 U6-12 START BIT always low

16 U6-11 DB8

17 U7-6 DB9

18 U7-5 DB10

19 U7-4 DB11

20 U7-3 DB12

21 U7-14 DB13

22 U7-13 DB14

23 U7-12 DB15 MSB measurement value

24 U7-11 STOP always high

Note The CRYSTAL CS5014 pin labeled "DB15" is actually the 13th bit of data

transmitted (DB0 through DB2 are missing in the table above).

Output Waveform

Figure 2-28 shows the transmitted waveform from the slow ADC board when all inputs

are at 0. As indicated in the previous table, the first bit transmitted is a STOP bit, or the

first output is a high. The next shift gives a low, or start bit. The third shift gives theLSB of the address until the end of the first byte. Then four stop bits are transmitted, a

start bit, the rest of the data, then a stop bit, and then the output is tristated, as indicated

by the decay curve after the last stop bit. Observation of the waveforms produced by a

working slow ADC Board shows the ADDRESS and DATA bits to be changing

continuously.




Figure 2-28: Timing Relationships of STROBE, CAL, end RS-232 Output




07/97 770.00696-NW Disassembly and Assembly 3-1

Disassembly and Assembly

IntroductionThis section provides detailed instructions for basic DITS tool and CAST-V scanner

assembly and disassembly.

Tools And Equipment Required• Spanner wrench - P/N 3.42484

• Chassis insertion and removal tool - P/N 3.30014

• DITS contact insertion and removal tool - P/N 3.29991

• Vise

• Miscellaneous handtools

• 18-in. crescent wrench or channel lock pliers

• Soldering iron and H.M.P. solder• RTV sealant - P/N .21102

• Loctite #620 - P/N .80953

• Loctite #242 - P/N .81785

• Loctite #290 - P/N .81784

• Loctite Primer "T" - P/N 789.00265

• Exxon Turbo Oil 2380 - P/N .81792

• Vacuum pump and accessories - (see 770.00013, Evacuation Procedure)

• Oil-fill gage - P/N 707.55673 (supplied with scanner)

• Oil-fill tube - P/N 707.55581 (3 are supplied with scanner)

• Hand pressure pump (Enerpac or equivalent) - P/N .88774

• Threaded ring tool - P/N 707.55578 (supplied with scanner)• Shrink tubing - clear - P/N .83755

• Oil treatment - P/N .22933

• Bearing tool - P/N 707.55615 (supplied with scanner)

• Seal sizing cylinder - P/N 707.55624 (supplied with scanner)

• Wire markers from kit - P/N .60009

Section

3



3-2 Disassembly and Assembly 770.00696-NW 07/97

Basic DITS Disassembly

Electronics and Directional Sub

Use the appropriate engineering drawings for reference when disassembling the tool

section assembly.

1. Place the tool section assembly on a clean, stable work surface.

2. Remove the female thread protector from the top of the tool section assembly.

3. Adjust the T-handle on the insertion and removal tool to retract its three tabs into the

cylinder. See detail A of Figure 3-1.

4. Insert the insertion and removal tool into the bottom of the tool housing, fitting the

wide slot of the insertion and removal tool over the wide tab of the connector. See

detail B of Figure 3-1.

5. Carefully match the alignment slot on the collar of the insertion and removal toolwith the alignment slot on the housing.

6. Pull back slightly on the T-handle (see detail B, Figure 3-1) and press the release

spring at the bottom of the handle. The spring action pushes in the handle about 0.5

in.

WARNING Be careful not to pinch your fingers when releasing the spring. Thespring moves toward and into the collar when released.

7. Rotate the T-handle 90° in either direction. When the handle reaches the 90°position, the release snaps into the locking position as shown in detail C of

Figure 3-1.8. Push in the spring-loaded release rod until it bottoms. See detail D of Figure 3-1.

The spring-loaded release rod pushes in the button on the connector so that the

button clears the housing.

Note You may need to push in the T-handle to relieve pressure on the release rod.

CAUTION When removing the connector from the housing, be sure to hold in the spring-loaded

release rod until the entire insertion and removal tool has cleared the housing. Releasing

the rod too soon could cause the button on the connector to damage the inner housing.




RELEASE ROD

RELEASE SPRING

ALIGNMENT SLOT

DITS BUTTONA INSERTION / REMOVAL TOOL

B

C

D

E

Figure 3 -1: Removing the DITS Connector from the Pressure Housing

9. With the release rod pushed in to its maximum depth, pull on the T-handle to ease

the electronics chassis out of the housing. As soon as the button on the connector

clears the housing, the release rod springs back into the locking position. Support the

I beam as it is removed.




Basic DITS Assembly

Electronics and Directional Sub

Use the appropriate engineering drawings for reference when assembling the tool section

assembly.

1. Adjust the T-handle on the insertion and removal tool to draw the three tabs into the

cylinder. See detail A of Figure 3-2.

2. Align the wide slot of the insertion and removal tool with the tabs on the connector.

See detail A of Figure 3-2.

3. While holding the insertion and removal tool and connector together in one hand,

use the other hand to pull back slightly on the T-handle and press the release spring

(see detail B of Figure 3-2) to let the T-handle move forward.

WARNING Be careful not to pinch your fingers when releasing the spring. Thespring moves forward and into the collar when released.

Turn the T-handle 90° in either direction to lock the insertion and removal tool to the

connector. See detail B of Figure 3-2.

4. Carefully match the alignment slot on the collar of the insertion and removal tool

with the slot on the housing. See detail B of Figure 3-2.

Figure 3 -2: Installing the DITS Connector into the Housing




5. Push in the release rod in to maximum depth, and hold it so that the button on the

connector does not damage the inside of the housing. Push the connector, with the

electronics chassis attached, into the housing. (See detail C of Figure 3-2.)

Note Make sure the button on the connector (spring loaded) is locked into the proper

position before releasing the insertion and removal tool.

CAUTION When you are inserting the connector into the housing, be sure to hold in the spring-

loaded release rod until the entire insertion and removal tool has cleared the housing.

Releasing the rod too soon could cause the button on the connector to damage the inner

housing.

6. With the release rod pushed in to maximum depth, press the release spring at the

bottom of the T-handle, and rotate the handle to place the spring below the T-handle.

7. Carefully pull the insertion and removal tool out of the housing.

Disassembly of the Cast-V Scanner

Reference Drawings

• Scanner assembly - 707.55531

• Housing assembly - 707.55532

• Motor assembly - 707.55530

Note Oil inside the scanner is at low pressure. Remove the oil plug slowly and shield

any oil spray with a rag.

Oil Drain

Remove the lower oil-fill plug on the scanner body (Loc. 25) and drain the oil. Remove

the upper oil-fill plug and check the valve (Loc. 25 and 47).

Transducer Holder Removal

Refer to drawing 707.55532.

1. Remove the head by loosening three set screws (Loc. 70) and unscrewing the collar

(Loc. 66). Remove the head carefully to avoid damaging the transducer leads.

2. Remove the terminal board (Loc. 73) and unplug the slip-ring wires.

3. Remove the head base and collar by removing the socket head cap screws (Loc. 71).




Face Seal Removal

Using an 18-in. crescent wrench, remove the seal retainer (Loc. 63). Carefully remove

the face seal assembly (Loc. 62) and spacer (Loc. 60). Take special care to avoid

damaging the face seal mating surfaces.

Housing DisassemblyNote The keys (Loc. 17) are threaded 5/16-18-UNC inside the two bolt holes. Thread a

bolt into these threads to aid in removal of the key.

1. Remove the cap screws and keys at the top of the tool (Loc. 17 and 18), and separate

the DITS sub (Loc. 16) from the keyed housing (Loc. 23).

2. Remove the small retaining ring on the hermetic connector (Loc. 20) to remove the

insulating wafer. Pull straight out on the wire bundle to unplug the wafer. Unsolder

the sockets, and remove the wafer.

3. Remove the bolts and keys (Loc. 17 and 18) and separate the keyed housing (Loc.

23) from the motor housing (Loc. 37). Carefully pull the wire bundle from the keyedhousing.

Mud-Cell Removal

To remove the mud cell transducer (Loc. 31) use tool P/N 707.55578, and unscrew the

threaded ring (Loc. 36). Using a 4-in. long 1/4-20 bolt or all-thread, remove the backup

plate (Loc. 35) and the wave-washer (Loc. 33). Gently push or tap on the front face of

the transducer to remove it.

Motor Assembly Removal1. Remove the bottom set of keys and bolts (Loc. 17 and 18) and carefully remove the

motor, slip ring, and keyed sub assembly.

2. Unsolder wires from terminals (Loc. 48) and loosen the coupling set screws (Loc.

50). Remove the motor-resolver assembly (Loc. 38) from motor mount (Loc. 49) by

removing the four screws (Loc. 75) from the motor mount.

Slip-Ring Removal

Remove the four screws (Loc. 75) attaching the motor mount (Loc. 49) to the keyed sub

(Loc. 59) and remove the mount. Remove coupling (Loc. 50) and pin (Loc. 51) from theslip-ring (Loc. 54) and shaft (Loc. 58). Carefully slide the slip-ring off the shaft while

removing the wires from the shaft bore.




Shaft and Bearing Removal

Use tool P/N 707.55578 to remove the two threaded rings (Loc. 56) from the keyed sub

(Loc. 59). Remove the shaft (Loc. 58) by lightly tapping on the end of the shaft with a

rubber mallet. The shaft drops out with one bearing attached. Remove the other bearing

in the keyed sub.

Assembly of the Cast-V Scanner

WARNING Do not use O-Lube on components during assembly. It is notcompatible with Turbo Oil.

Note All seals, except where noted, are to be lubricated with Exxon Turbo oil 2380.

Use Loctite #242 on all screws unless otherwise noted. Use Loctite #620 only where

noted because of high strength.

Motor-Resolver Assembly


1. Mount the resolver assembly on the end of the motor that contains the motor wires.

2. Loctite the keystock (Loc. 2) onto the motor shaft. Install, but do not Loctite, the

extension shaft (Loc. 6) onto the motor shaft.

3. Loctite the resolver rotor (Loc. 1) to the extension shaft (Loc. 6) using Loctite #620,

and push the rotor on until the end of the extension shaft is flush with the top end of the rotor. Use the keystock (Loc. 2) to align the resolver rotor and shaft.

4. Install the resolver mount (Loc. 5) to the motor as shown on 707.55530. Install but

do not tighten the two screws (Loc. 7) in the extension shaft. Install the resolver

stator.

5. Install the resolver retainers (Loc. 3), making sure they are flush with the OD of the

resolver mount (Loc. 5). They must lock into the groove on the OD of the stator.

6. Using a thin-bladed screwdriver, adjust the extension shaft through the 0.5-in. hole

in the resolver mount so that the top of the magnets in the rotor are exactly flush

with the top of the magnets in the resolver stator. Tighten the screws (Loc. 7) to

secure.7. Refer to setup procedure 770.00103 for resolver adjustment.

8. When properly set, the resolver rotates the motor shaft clockwise when seen

downhole.

9. Install the resolver cover (Loc. 9).

10. Wire the motor and resolver according to the wiring diagram on drawing 707.55532.




Motor Mount Assembly


1. Loctite the dowel pins (Loc. 46 and 52) to the motor mount (Loc. 49).

2. Install the eight terminal studs (Loc. 48).

3. Loctite the keystock (Loc. 53) to the motor shaft keyway.4. Slide the flexible coupling (Loc. 50) onto the motor shaft but do not tighten the set

screw.

5. Bolt the motor mount (Loc. 49) to the motor (Loc. 38).

6. Adjust the coupling so that the set screw is visible through the mount access hole

under the solder terminals. Tighten the coupling to the motor shaft.

Shaft Assembly


1. Loctite the dowel pin (Loc. 46) to the scanner shaft (Loc. 58) and the keyed sub

(Loc. 59).

2. Using a scribe or pick, remove the snap ring and shields from each side of the

bearings (Loc. 57). Clean out the packing grease, but do not spin the bearing dry

with shop air. Lubricate the bearings with Turbo oil.

CAUTION Do not use the threaded retainer ring (Loc. 56) to seat the bearings (Loc. 57) in the keyed

sub (Loc. 59). Use the bearing installation tool. Do not thread the retainer rings by hand

into the sub before installation of the shaft. If the retainer ring does not thread to bottom

easily, check the threads for burrs, especially around the area where the milled slot and the

threads meet. Use a small three-cornered file to clean the threads.

3. Use bearing installation tool 707.55615 to install the lower (downhole) bearing (Loc.

57) in the keyed sub (Loc. 59). Thread the retaining ring (Loc. 56) in place by hand.

4. Install the shaft (Loc. 58) into the sub.

5. Install the upper bearing (Loc. 57) onto the shaft and seat in the sub. Install the

retaining ring. Tighten both retainer rings using assembly tool 707.55578. Use hand

torque only. Do not wrench on this tool. Lock the rings in place by using a center

punch to stake or lock the threads of the ring to the mating threads of the sub. This is

done by center punching the ring on the top face near the thread area. Do not center

punch the keyed sub surface.

6. Install the O-ring (Loc. 55).

Slip-Ring Installation


1. Locate the slip-ring (Loc. 54), and slide a 2-in. long piece of shrink tubing over each

wire that exits the center rotor. Slide the tubing up to the rotor housing, and shrink with

heat.




2. Remove the existing vendor wire labels, and label each wire with markers from the

package (P/N .60009). Cover with clear shrink tubing to retain.

3. Install the slip-ring assembly onto the scanner shaft, and note the position to line up the

3/32-in. hole in the slip-ring hub with the hole in the shaft. Route each wire through the

angled holes in the shaft and out the end so that the labels are visible.

4. Secure the slip-ring to the shaft with pin (Loc. 51). Be careful if pulling the slip-ring

wires out the ID of the shaft so as to not nick or cut the wires.

5. Trim the wires 2-in. from the end of the shaft.

6. Loctite the keystock (Loc. 53) to the shaft.

7. Line up the slot on the OD of the slip-ring body with the dowel pin (Loc. 52) on the

motor mount. Align the shaft with the coupling, and route the wires from the slip-ring

through the 1-in. hole in the motor mount.

8. Bolt the keyed sub and the motor mount together using screws (Loc. 75).

9. Tighten the coupling screws (Loc. 50).

10. Solder the slip-ring wires in numerical order to the terminals. Secure the wires with

high-temperature lacing cord.

Face Seal Installation

Refer to drawing 707.55532).

CAUTION Use extreme care when handling the face seal components. Scratches on the sealing

surfaces cause the seal to leak oil.

1. Lightly lubricate the seal end of the shaft as well as the ID of the rubber bellows (Loc.

62) with S.T.P. Oil Treatment (P/N .22933). Install the seal spacer (Loc. 60) over the

output end of the shaft with the short end facing downhole. Slide the seal assembly

(Loc. 62) (spring and bellows assembly) onto the shaft. Slide the seal along the shaft

several times to ensure the rubber bellows seal lip has not rolled on the shaft.

CAUTION The primary ring must be installed correctly. The tapered end must face downhole to

contact the polished surface of the mating ring.

2. Locate the primary ring, and apply a thin film of silicon grease to the back face of

the ring. Install the primary ring over the shaft, and align the notches on the ring

with ears on the bellows retainer. The grease contacts the rubber bellows, keeping

the primary ring secure against the bellows assembly.

3. Apply a thin film of Turbo Oil to the face of the primary ring.

4. Lubricate the mating ring face and O-ring (Loc. 72) with Turbo Oil and install in the

retainer (Loc. 63) with the polished face uphole toward the primary ring and bellows

assembly.

5. Install the O-ring (Loc. 61) onto the retainer. Thread the retainer in the keyed sub

and tighten.




Keyed Sub and Motor Housing Assembly


1. Loctite the three dowel pins (Loc. 67) in place, and install the O-rings (Loc. 68 and

69) in the head base (Loc. 65).

2. Slip the collar (Loc. 66) over the base, and pull the slip-ring wires through the hole

in the center of the base (Loc. 65). Align the dowel pin (Loc. 46) and install the baseto the scanner shaft (Loc. 58) with the four screws and lock washers (Loc. 71 and

85). Use Loctite #290 on these screws.

3. Solder the pins (Loc. 86) to the slip-ring wires according to Note 17 on the drawing

and plug the wires into the correct numbered socket on the terminal board (Loc. 73).

Cover both the pin and socket with a length of shrink tubing according to Note 18 on

the drawing.

4. Secure the slip-ring wires to the motor OD with high-temperature lacing cord

according to Note 15 on the drawing.

5. Slide the motor assembly into the motor housing (Loc. 37), and align the grooves on

the OD of both housings.6. Install the keys (Loc. 17) using the bolts (Loc. 18).

Mud-Cell Assembly


1. Install the O-ring (Loc. 30) onto the mud-cell transducer (Loc. 31) and solder a 24-in.

length of wire (according to the wiring diagram). Cover the joint with RTV.

2. Install the transducer into the housing (Loc. 23) according to the drawing.

3. Install the transducer protector plate (Loc. 32), the wave spring (Loc. 33), and thebackup plate (Loc. 35). A small amount of silicon grease holds the wave spring to the

backup plate during installation. The transducer wires pass through the slot in the

bottom of the backup plate. The dowel pin aligns in the slot in the back of the

transducer.

4. Thread the retainer ring (Loc. 36) in place (the transducer wires must pass through the

center of the retainer ring), and tighten the ring with assembly tool 707.55578. Route

the wires according to notes on the wiring diagram.




Pressure Balance Assembly


Note The CGT ring assembly (Loc. 43) must be properly sized before installation into the

pressure balance cylinder (Loc. 40).

1. The CGT ring seal assembly consists of three parts: the two backup rings, the energizer

ring, and the cap seal. See Figure 3-3. Install the energizer ring and the two backup

rings onto the piston (Loc. 42). Place the cap seal into boiling water, and allow it to

soak for approximately 1 min. Remove the cap seal from the water, and carefully

stretch it over the piston and onto the top of the energizer ring and between the backup

rings. Use a piece of lacing cord to stretch and work the cap seal over the piston, but do

not overstretch. After the cap seal is located over the energizer ring, carefully squeeze

the cap seal with your hand to form-fit it around the energizer ring.

CAUTION Insure that the piston is square with the cylinder before insertion. If not square, the cap seal

will be damaged. If the piston is square with the cylinder, the piston slides into the cylinder

easily.

2. Place the piston assembly, without slydring (Loc. 41) installed, into cold water for

about 1 min. Lubricate the ID and ends of sizing cylinder 707.55624 with Turbo Oil

and carefully slide the piston assembly, seal end first, into one end of the cylinder.

Allow this assembly to sit for about 1 min and then remove the piston from the sizing

cylinder, and install the slydring (Loc. 41). Install the piston assembly into the pressure

balance cylinder (Loc. 40) as shown on the drawing.

3. Install the O-rings (Loc. 24 and 27) onto the piston compensator sub (Loc. 39).

4. Thread the sub (Loc. 39) into the cylinder (Loc. 40), and tighten it.

Note The pressure balance cylinder (Loc. 40) is thin-walled material. Do not clamp or

wrench on the OD.

5. Place the spring (Loc. 44) on the back side of the piston and screw on the spring

retainer (Loc. 45). Carefully thread this assembly into the housing (Loc. 23), and

tighten.




Slydring

Backup Ring

Energizer Ring

Cap Seal

Figure 3 -3: Piston Seals

Motor Assembly and Keyed Housing Assembly


1. Route the wires from the motor section through one of two small holes in the keyed

housing. See the wiring diagram for details.

Note The resolver wires must be routed separate from the motor wires.

2. Carefully mate the two housings aligning the grooves on both housings. Install the

keys and bolts (Loc. 17 and 18).

DITS Upper Sub Assembly


1. Route the color-coded wire from the motor-resolver assembly through the properly

numbered hole in the hermetic connector wafer, and solder onto the socket. See the

wiring diagram.




2. Install the O-rings (Loc. 68) onto the hermetic connector (Loc. 20) and seat the

connector in the housing.

3. Install the retaining ring (Loc. 22).

4. Install the O-ring (Loc. 21) onto the sub and install the DITS hardware. Wire the

DITS connector to the hermetic connector according to the wiring diagram.

5. Plug the wafer from the motor assembly into the hermetic, and install the waferretaining clip.

6. Complete the wiring according to the wiring diagram.

7. Mate the upper sub to the motor assembly, and install the two keys and cap screws.

Holder and Transducer Assembly


1. Refer to assembly drawing 707.55531 for the holder and transducer selection and

installation.

2. Plug the transducer leads to the proper socket on the terminal board (Loc. 73), and

cover both the pin and socket with a piece of shrink tubing.

Oil-Fill Procedure1. There are two evacuation ports on the scanner body and one on the transducer

holder. The upper port on the housing is threaded deeply for a removable check

valve (Loc. 47) as shown on drawing 707.55532. Remove the check valve assembly

when evacuating the tool.

2. Install three oil-fill tubes (P/N 707.55581), and evacuate the tool. Then fill the tool

with Exxon Turbo Oil (P/N .81792) according to Specification 770.00013.

WARNING Do not apply silicon grease around the shaft to seal a vacuum leak atthe face seal. The vacuum leak sucks the grease inside the tool anddamages the sealing surfaces of the face seal. If a leak persists,remove the fill-tube at the bottom of the head, and install the oil plug.Stand the tool vertically with the head in a large can filled with TurboOil. The oil level must completely cover the face seal area. Securethe tool vertically, and continue evacuation.

3. After the tool is oil filled, remove the fill tubes and replace the lower scanner plug

(Loc. 25) and head plug. Install the check valve (Loc. 47) in the upper fill port, andreinstall a fill tube.

Note The check valve must bottom out in the housing to allow room for the plug to be

installed above it.

4. Install a piece of ¼-in. Tygon tubing (or similar tubing) to a hand-pressure pump

filled with Turbo oil. Stroke the pump several times to bleed any air out of the

tubing, and top off the fill tube with oil. Secure the tubing to the fill tube with a

small hose clamp.




5. Pump the piston back with oil until the score mark on the oil fill gage P/N 707.55673

is aligned with the inside face of the spring cap (Loc. 45). See Figure 3-4 and

drawing 707.55531 for piston set dimensions and gage position.

6. Bleed the pressure off the pump. Remove the oil-fill tube, and install the fill port

plug. It is not uncommon for the check valve to leak a small amount of oil. If the

check valve leaks excessively and does not hold pressure, then remove it and clean

out the valve by depressing the ball and blowing air or soaking the valve in solventto remove any debris between the ball and seat. If the valve continues to leak, use a

small brass flat tip punch to strike the ball from the washer and spring side. Striking

the ball increases the seat sealing area. If the check valve continues to leak

excessively, remove and wrap the threads with Teflon tape. Wrap only the thread

area, and trim away any excess tape.

7. Install the cover (Loc. 28).

OIL FILL GAGE

GAGE MARK

Figure 3 -4: Piston Gage Position

Pressure and Temperature Test

Note This test is for Fort Worth Manufacturing only.

WARNING Do not pressure test the scanner in cold water. Such testing couldcause the transducers to fail.

1. Install the scanner in the chamber.




2. Ramp temperature and pressure to 175°F and 10,000 psi, according to Section 5,

Paragraph 3 of Halliburton Engineering Specification 770.10012.

3. Stabilize the temperature and pressure. Hold these settings for 10 min.

4. When the chamber internal temperature has dropped 125°F or below, the chamber

pressure can be reduced to ambient pressure and the tool removed.

Adjustment of the Motor/Resolver AssemblyThis section provides instructions for positioning the resolver in the motor-resolver

assembly 707.55530.

Equipment Required• CAST-V electronics or simulator board

• DC power supply (current capacity at least 1.0 A)

• Oscilloscope

• 120-Vac, 60-Hz supply

Reference Drawings• 707.55530 Motor Assembly - Scanner

• 707.55567 Modification - Chassis Assembly - DITS CAST to CAST-V

• 707.55595 Chassis Assembly - Electronics - CAST-V

Procedure

Note This procedure is intended to be used with the motor-resolver assembly

707.55530 with no additional hardware attached to the output shaft of the motor.

After the resolver has been mounted to the motor, resolver wires REFA (RED/WHT),

SIN (RED), COS (BLU), and RGND (BLK, YEL & YEL/WHT) are connected to the

CAST-V electronics chassis (refer to Figure 3-5) with connector pins P1-21, P1-14,

P1-15, and P1-22, respectively.




BLU

RED/WHT

Motor

1 Ampere Capacity Bench Supply20 Vdc Maximum

P1-14

P1-22

P1-15

P1-21

(RGND)

(RGND)

YEL/WHT

YEL

BLK

Resolver

MOT2BLK

MOT1RED

MOT3GRN

(SIN)RED

(RGND)(COS)

(REFA)

INSTRUMENTPOWERSOURCE

PIN 13PIN 14

AC VoltageInput

VariableVoltage

Transformer

IsolationTransformer

V40 DSPDATAACQ.

PREAMP/FIRE

– +

Figure 3 -5: Setup Connections for Resolver Adjustment with the CAST Tool

If the simulator board is used, make the resolver connections as shown in Figure 3-6.

Figure 3 -6: Setup Connections for Resolver Adjustment with the Simulator Board




Fixed Position Alignment

The following steps align the motor rotor and stator to a fixed position. This fixed

position ensures that the commutation sequence and direction of rotation is correct.

1. Rotate the rotor by hand until the rotor keyway is aligned with the orientation hole

located under the resolver mounting flange (Figure 3-7).

MOTOR HOUSING

RESOLVERSTATOR

WIRES

Figure 3 -7: Relationship of the Keyway to the Orientation Hole at Electrical Zero

2. Connect motor wires 2 (BLK) and 3 (GRN) together.

3. Using a dc power supply with sufficient current capacity (> 1.0 A), connect motor

wire 1 (RED) to the positive terminal, and connect motor wires 2 (BLK) and

3 (GRN) to the negative terminal.

CAUTION Motor windings have low resistance and require less than 8 V to develop 1 A of current.

Keep the current below 1.5 A.

4. Turn on the dc power supply. Apply 1 A to the motor to lock the rotor in place. The

rotor keyway aligns exactly with the motor orientation hole upon the application of

power. The motor rotor and stator are now aligned. Proceed immediately to Step 3

while maintaining power to the motor.




Electrical Zero Alignment

The following steps align the resolver stator with the resolver rotor to obtain electrical

zero (EZ). At EZ, a +5-V pulse is generated at pin U1-35 on the R-to-D board

707.55561.

1. Use a scope probe to monitor the voltage level at U1-35 on the R-to-D board. Set the

scope to AUTO TRIGGER to view only the steady-state dc level at this pin.

2. Rotate the resolver stator by hand until the voltage at U1-35 shifts to +5-V as

observed on the scope.

3. While maintaining the voltage level at +5-V, tighten the clamps that hold the

resolver stator in place. The +5-V output voltage is sensitive to the orientation of the

resolver rotor and stator.

4. Turn off the dc motor power supply and the ac tool power supply.

5. Disconnect the motor wires from the dc power supply. Separate motor wires 2

(BLK) and 3 (GRN). Connect all three motor wires to the tool chassis by P1, as

shown in Figure 3-8, or to the simulator board as shown in Figure 3-9.

BLU

RED/WHT

Motor

1 Ampere (or Greater) Capacity0 to 150 Vdc Maximum

P1-14

P1-22

P1-15

P1-21

(RGND)

(RGND)

YEL/WHT

YEL

BLK

Resolver

(SIN)RED

(RGND)

(COS)

(REFA)

INSTRUMENTPOWERSOURCE

PIN 13PIN 14

AC VoltageInput

VariableVoltage

Transformer

IsolationTransformer

V40

MOT + MOT –

DSPDATA

ACQ.PREAMP/FIRE

+ –

P1-36

P1-35

P1-37

MOT2BLK

MOT1RED

MOT3GRN

Figure 3 -8: Run Connections for the Motor with the CAST Tool




– +

+

RATE0TACHRATE2RATE1START

Resolver

Motor

COMMUTATORJ1-15

J2-5 J1-9

J2-10

J1-13

J2-4 J1-8

J2-9

J1-12

J2-3J2-15

J1-3

J2-8

J1-8

J2-2J2-14

J1-2

J2-7 J1-15

J1-6

J2-1J2-13

J1-1

J2-6 J1-10

-15+15+5GND

POWER SUPPLY

COS

SIN

RGND

REFAORG

YEL

GRN

BLU RED

BLK,YEL,YEL/WHT (3 WIRES)

BLU

RED/WHT

150uF

J 3 7

J 3 7

J 3 8

J 3 8

J 3 9

J 3 9

J 3 6

J 3 2

J 3 5

J 3 1

Power Supply0 to 150 Vdc at 1 amp

MOT A+MOT A –

MOT B+

REF A

COS

RGND

SIN

MOT B–

MOT C+

MOT C–

BLK

RED

GRN

MOT2

MOT1

MOT3

WHT/YEL

WHT/ORN

WHT/RED

Figure 3 -9: Run Connections for the Resolver Setup with the Simulator Board

CAUTION When examining signals on the commutator board do not touch the chassis while

touching the case of transistors Q1, Q4, or Q7. The commutator drive waveform will

become unbalanced, allowing high surge currents to blow FETs.

Turn on the tool power (120-Vac). As a quick check to monitor the EZ setting, rotate the

rotor by hand until the rotor keyway is roughly aligned with the orientation hole under

the resolver mounting flange (refer to Figure 3-7). As previously in Step 3, monitor the

EZ voltage with an oscilloscope or voltmeter. As the rotor keyway passes through the

location of the orientation hole, there should be a +5-Vdc pulse at U1-35 on the R-to-D

board (707.55561).

Note This step is only meant to serve as a visual check. However, if the angular

difference between the rotor keyway and the orientation hole is noticeable when the +5-

V pulse occurs, loosen the resolver stator clamps, and repeat Steps 3 through 5.

Apply dc motor power sparingly. The motor begins to spin at around 3-Vdc.

Note Do not spin the motor at high speeds or for an extended time at low speeds.

Motor bearings are only lightly lubricated. This spinning could damage bearings.

Motor-resolver setup is now complete. Disconnect the motor and resolver wires from the

electronics, and complete the assembly of the scanner.




07/97 770.00696-NW Calibration and Verification 4-1

Calibration and Verification

IntroductionThis section contains instructions on calibration.

Calibration of the Directional SubThis subsection discusses the calibration and testing of directional sub chassis assembly

(707.55562) used in directional sub assembly (707.55572).

General

The directional sub for the CAST-V tool contains a biaxial inclinometer (707.30905), atwo-axis magnetometer sensor assembly (.77800), and a compass board (707.55574).

Power is obtained from the CAST-V electronics package. All output signals from the

directional sub are near dc and are further processed at the slow ADC board in the

CAST-V electronics package.

Several FA on the compass board require adjustment for calibration of the

magnetometer. FA values must be adjusted with the same sensor assembly connected to

the board as to be used in the finished tool.

Biaxial inclinometer adjustments at the compass board consist of two FAs. The

inclinometer itself is a purchased item requiring no internal adjustments. The

inclinometer adjustments on the compass board match the signal level from the

inclinometer to the ADC measurement range.

After calibration, a heat run is made to 175°C with the directional chassis in a heated

sleeve so that the chassis can be rotated and tilted as heat is applied. Data are recorded

for QC files at this time.

Section

4



4-2 Calibration and Verification 770.00696-NW 07/97

Equipment

This calibration procedure is accomplished without the CAST-V electronics, but with

standard lab test equipment for all measurements. Equipment required is as follows:

• power supply, ±15-Vdc at 100 mA, metered

• digital voltmeter, 4 ½-in. digits

• calibration stand assembly (707.55635)

• 37-pin DITS connector to mate to top of tool with leads for testing

• ohmmeter (Triplet 630 NS or equivalent)

• electrically heated sleeve for the chassis which will mount in test stand

• oscilloscope

• gaussmeter (necessary only if local earth flux levels are unknown).

Magnetometer AdjustmentCalibration must be done in a building with no substantial amount of iron or steel. The

flux field of the earth must be parallel throughout the space that the tool measures. This

procedure assumes a normal (approximately 0.5-gauss) magnetic field strength.

Many of the adjustments depend on the exact characteristics of the sensor assembly and

its precise orientation to the earth's magnetic field. Therefore, the compass board cannot

be adjusted correctly without a calibration stand assembly.

The test stand must be aligned with magnetic north. Use a magnetic compass held at the

approximate position of the sensor assembly for reference. When the stand is locked in a

vertical position, the fixed pointer on the rotating protractor (as opposed to the fixed

deviation, or tilt, protractor) points directly at magnetic north.

Install the directional chassis into the test stand as shown in Figure 4-1. Ensure that the

DITS button on the chassis assembly is aligned with the "0 degree" mark on the

protractor, which measures the rotation of the tool. At this point, the DITS button of a

chassis installed in the stand faces exactly north when zero on the protractor is set to the

fixed pointer of the stand. Hang the compass board loose on the wiring harness so that

the adjustments are accessible. Connect the wiring to the meters and power supplies, as

shown in Figure 4-2.




707.71547

707.55619

.86540

707.55562

707.5561.11346 (3)

Figure 4 -1: Test Stand Setup




Figure 4 -2: Test Setup Wiring




Adjustment Procedure

The following procedure is used to adjust the compass board. The sensor drive signal is

adjusted first. Then the amplifiers and other electronics are adjusted to condition the

signals from the sense coils.

1. Temporary resistors should be installed in all FA slots. Approximate values are as

follows:

• R37 = 1740 Ω

• R19 = 13 k Ω

• R20 = 13 k Ω

• R18 = 10 k Ω

• R1 = 10 k Ω

• R11 = 20 k Ω

2. Apply power while observing current from the supply:

• Positive supply current should be < 45 mA.• Negative supply current should be < 40 mA.

Note Current varies with the position of the chassis. Position the chassis horizontally,

and rotate 360° while watching the current meter. Use the largest current reading seen

during the rotation.

3. Adjust the frequency of U3 (connect a counter or scope to either end of R42) by

adjusting FA resistor R37. Set the frequency should to 27 ± 2 kHz.

4. Refer to the waveforms in Figure 4-3. The OSCOUT (U3-4) triggers the one-shot

U6/A. The trailing edge of U6/A-6 triggers U6/B, which generates a negative-goingpulse timed to encompass the moment of saturation of the sensor. The saturation is

visible with a scope connected to TP-1. The negative-going pulse is visible with a

scope connected to TP-5. It is not necessary to exactly center the moment of

saturation in the TP-5 pulse. If the timing and the position of the gate look good,

then proceed.




Figure 4 -3: Gate Timing Relationships on the Compass Board

5. Compare output waveforms at TP-2 and TP-4 to Figure 4-4, trace B. Rotating the

tool changes the amplitude and polarity, but the waveshape should be similar. An

exact match is not required, but if the waveforms are not similar, problems will arise

later in this procedure.




Figure 4 -4: Signal Waveforms on the Compass Board.

6. Measure dc voltage at the positive lead of TP-6. The voltage at TP-6 should be 9- to

12-Vdc.

Note "J1" refers to the upper 37-pin DITS connector of the directional sub.

As the chassis is rotated, an ideal plot of MAGX and MAGY output voltages (measured

with a digital voltmeter at J1-25 and J1-24) shows sine and cosine waveforms

symmetrical about ground. To get closer to ideal, adjust the peak amplitudes of MAGX

and MAGY to get the same peak voltage for positive and negative swings.

7. Rotate the chassis assembly through a full 360° and note the polarity and amplitude

of the output signal at MAGX (J1-25). Locate the point in the rotation where the

amplitude peaks, and note the voltage. Rotate the coils 180° to the opposite peak

polarity, and again note the voltage. These two voltages differ a little in amplitude.

Adjust R19 FA until the opposite polarity peak voltages are the same magnitude.

Repeat the adjustment procedure until the symmetry is correct (1% match is usually

obtainable).




Note Ensure that the positive peak of the MAGX (J1-25) voltage occurs when the

DITS button is pointed north (near 0°).

8. Switch the voltmeter to MAGY (J1-24). Once again rotate the chassis assembly, and

note the peak voltage swings. Set R20 FA to adjust the voltage swings to obtain

equal plus and minus peak readings. When symmetry has been established, note the

peak positive voltage for use in the next step.

Note Ensure that the peak positive MAGY (J1-24) voltage swing occurs when the

chassis is rotated to near 90°.

9. Switch the voltmeter to MAGX (J1-25), and rotate the chassis to get a peak positive

output. Use R11 FA to set the amplitude of the peak voltage to the same as was

recorded in Step 8.

Rotation of the chassis assembly yields the same plus and minus voltage peak swings out

of MAGX and MAGY. All that remains is to electrically rotate the output of MAGY to

be exactly 90° from the zero of MAGX.

10. Connect a digital voltmeter to MAGY (J1-24). Rotate the chassis assembly to get

zero volts on the meter. Set the movable pointer on the rotating protractor to a

convenient reference point (0 degrees or 180 degrees).

11. Connect the digital voltmeter to MAGX (J1-25). Rotate the chassis assembly until

the voltmeter reads zero. This point should occur exactly 90° from the point of

rotation noted in step 10. The zero point is probably off from the point noted in Step

10 by 90° plus or minus a few degrees (an error of 5° or less is expected). Adjust R1

FA until the MAGX zero point occurs exactly 90° from the MAGY zero as noted in

Step 10.

Recheck of Magnetometer Adjustment

To recheck the magnetometer adjustments, rotate the chassis assembly in the test standwhile observing that:

1. The peak amplitude for plus and minus output of each axis is near the same peak

voltage.

2. The 0-V point for the MAGX (J1-25) occurs at 90° from the 0-V point of the MAGY

(J1-24).

3. The MAGX and MAGY output voltages are equal when the test stand protractor

indicates 45 ± 1° from the MAGY zero.

Install the compass board in the chassis. Rotate the chassis until the DITS button points

to magnetic north 0° on the protractor). Loosen the fasteners (Loc. 34 on drawing

707.55562), and adjust the position of the sensor to get 0 V out of the MAGY (J1-24)output. Tighten the fasteners after adjustment is complete.




Inclinometer Adjustment

The purpose of this section is to provide instructions on test stand setup to hold the

chassis horizontal.

Adjustment Procedure

1. Apply power, and meter the INCLX (J1-26) and INCLY (J1-27) output voltages.

2. Rotate the chassis until the INCLX voltage peaks (either positive or negative). At

this point, adjust trim pot R10 to get exactly 4.00-Vdc output.

3. Rotate the chassis until the INCLY (J1-27) voltage peaks. Adjust R8 to get exactly

4.00-Vdc output.

Quality Control Data Collection (And Temperature

Testing)

Collect the data to be filed. Data collection consists of a series of voltmeter readingstaken at ambient temperatures followed by similar voltmeter readings taken with chassis

at 175°C. Enter each voltmeter reading into the data collection sheets provided or copies

of the sheet. The steps below outline the procedure used to complete the data sheets.

Page 1, Data Sheet Instructions

1. Using an ohmmeter, perform the continuity checks required for entries 1 through 13.

2. Install the chassis in the heated sleeve, but do not turn on sleeve power yet.

3. Connect power to the chassis and record the current drain from the ±15-Vdc supply

to the chassis.4. Record the peak voltage from the INCLX axis output (chassis horizontal and rotated

to get peak). INCLX peaks positive when the DITS button is up.

SPECIFICATION : INCLX peak voltage is 4.00 ±0.02-Vdc at ambient temperature.

5. Record the peak voltage from the INCLY output (chassis horizontal and rotated to

get peak. The maximum positive voltage occurs when the DITS button is rotated

clockwise 90°).

SPECIFICATION : INCLY peak voltage is 4.00 ±0.02-Vdc at ambient temperature.

Page 2, Data Sheet Instructions1. Adjust the chassis assembly to vertical, and set MAGY (J1-25) to 0-Vdc with the

DITS button pointing north. Adjust the pointer on the stand until it points to zero on

the protractor.

2. Rotate the chassis assembly, recording the MAGX (J1-25) and MAGY (J1-24)

voltages at 45° increments for a full rotation.

3. At each of the 45° increments, calculate the angle measured as shown below.




θ θ

θ φ=

××

+arctan

sin

cos

ΑΑ

,

where

A = peak amplitude of MAGX or MAGY

• ACos(θ) = MAGX = Signal at J1-25 (upper DITS connector)

• ASin(θ) = MAGY = Signal at J1-24 (upper DITS connector)

θ = angle measured from magnetic north

φ = rotator to place the angle in the right quadrant

The operator is obtained by examination of the polarity of the voltages seen at the

x-axis and y-axis output. For the magnetometer circuitry we are discussing, is

determined as follows:

• If MAGX is positive,

• and MAGY is positive, then = 0

• and MAGY is negative, then = 360

• If MAGX is negative,

• and MAGY is negative, then = 180

• and MAGY is positive, then = 180

The angle calculated from the voltages is recorded on the form provided.

SPECIFICATION : The calculated angle is < ±1.5° from protractor readings at ambient

temperature.

4. Measure the voltage at J1-28.

SPECIFICATION : The temperature sensor voltage at 25°C will be 1.36 ±0.1-Vdc. (If

the temperature at test is other than 25°C, correct at the rate of 0.005 V/ °C)

5. Heat the directional sub to 175°C and repeat Steps 1 through 4, using the elevated

temperature specifications below.

SPECIFICATION : At 175°C, the calculated angle will be < ±3° from ambient

protractor readings.

SPECIFICATION : The temperature sensor voltage at 175°C will be 2.24 ±0.1-Vdc.




HALLIBURTON LOGGING SERVICES

QUALITY CONTROL RECORDS

DIRECTIONAL SUB

DIRECTIONAL SUB SERIAL No.____________________________

INCLINOMETER SERIAL No._______________________________

PROJECT No.___________________________________________

TECHNICIAN AT TEST____________________________________

DATE OF TEST__________________________________________

PAGE 1 OF 3




DATA COLLECTION SHEET

FOR DIRECTIONAL SUB

DC MEASUREMENTS AT AMBIENT

1. Continuity from J1-1 to P1-1 (Y/N) _____

















18 Continuity from J1-37 to P1-37 (Y/N) _____

19. Current from +15-Vdc supply _____mA

20. Current from -15-Vdc supply _____mA

21. Inclinometer INCLX peak voltage _____Vdc

22. Inclinometer INCLY peak voltage _____Vdc

DIRECTIONAL SUB SERIAL No. INCLINOMETER SERIAL No.

________________________ ______________________

PAGE 2 OF 3




DATA COLLECTION SHEET FOR

DIRECTIONAL SUB HEAT TEST

MAGX

Vout AMBIENT

MAGY

Vout AMBIENT

CALC.

ANGLE,DEG.

MAGX

Vout 175 °C

MAGY

Vout 175 °C

CALC.

ANGLE,DEG.

0 DEG

45 DEG

90 DEG

135 DEG

180 DEG

225 DEG

270 DEG

315 DEG

INC.

Vmax

N/A N/A

TEMP. N/A N/A N/A N/A

TECHNICIAN DATE

____________________________ __________________________

DIRECTIONAL SUB SERIAL No. INCLINOMETER SERIAL No.

___________________________ __________________________

PAGE 3 OF 3




Directional Sub CheckThe directional sub requires two types of measurement checks: a magnetometer

measurement check (the azimuth) and an inclinometer measurement check (the relative

bearing). The two-axis magnetometer measures the tool orientation with respect to

magnetic north, while the two-axis inclinometer measures tool orientation with respect

to the high side of hole, and hole deviation. Thus, setup the directional sub on the test

stand, powered up by the logging system, and place it in several positions so that

readings from the test stand and the logging system can be taken and compared.

Comparing the readings from the logging system and the test stand determines the

operating condition of the directional sub.

Test Stand Setup

Refer to Figure 4-5, and use the following steps to ensure the directional sub is operating

properly.

Figure 4 -5: Vertical Stand Position

1. Place test stand 707.71547 on a flat, smooth surface, far away from metal that might

disturb the earth’s magnetic field.

2. Using a compass, align the test stand with respect to magnetic north.




3. Adjust the three screws at the base of the test stand until the stand is level using a

carpenter’s level or equivalent. Use the level to set the cradle vertically, and then set

the adjustable pointer on the semicircular disc to 0°.

Installing The Directional Sub Chassis

Install directional sub chassis assembly 707.55562 onto the test stand (see Figure 4-5).1. Install the adapter (707.55618) onto the test stand using three socket-head cap screws

(0.11346). Notice that the threads of these screws are metric.

2. Mount the directional sub chassis in the test stand by inserting the lower DITS

connector into the adapter (707.55618). Place the upper bracket (707.55619) over the

top DITS connector and clamp it to the test stand. Ensure that the chassis can be rotated

freely and that the top bracket is placed low enough on the tool to allow the jumper

cable to be plugged into the top of the directional sub.

3. Connect the 37-pin jumper cable (3.48659) from the top of the directional chassis and

to the bottom of the CAST-V electronics (707.55598). Use the standard 19-pin DITS

jumpers to connect the DSTU/D2TS and the cablehead to complete the toolstring.

4. Ensure that the EXCELL 2000 logging system is set up properly (refer to the EXCELL

2000 CLASS Logging System User’s Guide, 770.01032). Next, enter “Service Selection

2330” on the EXCELL 2000, and then select the DGR configuration to display

azimuth, relative bearing and deviation on the standard logging screen.

Magnetometer Check

Use the following to check the directional sub magnetometer.

1. Position the directional sub chassis and cradle to vertical with the pointer on the semi-

circular disc set to 0°.

2. Rotate the directional sub chassis and cradle until the fixed pointer on the cradle aligns

with 0° on the circular disc. The DITS button is now aligned with north, and the

logging screen displays 0 ±3 ° for AZIMUTH.

Note: If the value for the azimuth is not within ±3°, refer to the Directional Sub

Calibration Procedure (770.10566) for instructions on adjusting the magnetometer

circuitry. If the value of the azimuth is consistently off tolerance in the same direction (for

example, each reading is 3.5° clockwise of the true azimuth), then either the magnetometer

sensor is out of position, or the test stand is not oriented correctly. In either case, it may not

be necessary to go through the entire directional sub calibration procedure.

3. Rotate the directional sub chassis and cradle clockwise at 45° increments, and

compare the circular disc readings with the logging screen AZIMUTH readings. If

both readings are within ±3° at each increment, then the directional sub

magnetometer is functioning correctly.




Inclinometer Check

Use the following to check the directional sub inclinometer.

1. With the directional sub chassis and cradle still positioned to vertical (as in Step 3 of

Test Stand Setup), verify that the reading for DEVIATION on the logging screen

displays

0 ± 2°.2. Incline the directional sub chassis and cradle to 45° and then 90° (see Figure 4-6).

Compare the semi-circular disc reading to the logging screen DEVIATION reading for

each setting. The semicircular disc readings and the logging screen DEVIATION

readings should be within ±2°.

ADJUSTABLEPOINTER

SEMI-CIRCULAR

DISC

COUNTERCLOCKWISEINCLINATION

SOUTH NORTH

CIRCULARDISC

FIXED POINTER90°

Figure 4 -6 : Stand Position for 90-Degree Inclination

3. Incline the directional sub chassis and cradle to 5° on the semicircular disc (see

Figure 4-7) and rotate the directional sub and cradle to 0° on the circular disc. The

logging screen should display 0 ±2° for RELATIVE BEARING.

Note: The accuracy and stability of the relative bearing reading decreases in deviations

of less than 2°.




Figure 4 -7 : Stand Position for 5-Degree Inclination

4. With the directional sub and cradle set at a 5° deviation, rotate the cradle circular disc

clockwise in 45° increments, and monitor the circular disc reading and the RELATIVE

BEARING reading on the logging screen at each increment. The circular disc readingsand the RELATIVE BEARING readings should agree within ±2°.

5. Repeat Step 4 at 45° and 90° deviations (counterclockwise from 5°). If the circular disc

readings and the logging screen RELATIVE BEARING readings are within ±2° for

each setting, then the directional sub inclinometers are functioning correctly.

Switch to the Processed Telemetry Logging Screen, and verify that the temperature as

indicated on the logging screen is within 9° of the ambient temperature.




07/97 770.00696-NW Troubleshooting 5-1

Troubleshooting

IntroductionThis section addresses the testing of a complete CAST-V electronics chassis assembly

(707.55595) or a DITS CAST modified to CAST-V by 707.55567.

Required Equipment• Digital voltmeter

• Dual trace storage oscilloscope

• PC with 1553 bus adapter card (3.35000)

• CAST-V monitor program - CMON.EXE (707.55634)

• Ground isolated variable voltage (0- to 120-Vac) supply

• 0- to 150-Vdc 1.5-A supply (Sorenson DCS 600-1.7 or equivalent)

• Dial-A-Source or equivalent reference dc supply

• DITS 37-pin jumper cable with breakout box

• Test transducer with fixturing (Figure 5-1)

• Sine wave oscillator, 300 to 500 kHz with 10-V p-p output level

• 50-Ω step attenuator, 3-dB steps to -60 dB

• AC voltmeter, HP 400 EL or equivalent

• Miscellaneous handtools

• Load box for testing power supply

• 5-Vdc load = 5 Ω

• +15-Vdc load = 50 Ω

• -15-Vdc load = 50 Ω• 400-Vdc load = 80.6 k Ω

• Jumper to intercept tool wiring to inverter board (refer to Figure 5-2 for jumper

wiring and parts list)

Recommended devices:

• HP355D provides 0 to 120 dB in 10-dB steps

• HP355C provides 0 to 12 dB in 1-dB steps

Section

5



5-2 Troubleshooting 770.00696-NW 07/97

CAST-V TestingA test setup as shown in Figure 5-1 is recommended.

CAUTION Use the ground isolation transformer in the 120-Vac power circuit. If deleted, the chassis

will be 60-Vac above earth ground when powered up, possibly destroying the test

equipment and chassis components and delivering electrical shocks to personnel.

All the items illustrated in Figure 5-1 are not necessarily required until the final heat test.

A slightly different test setup is required (Figure 5-3) for testing the accuracy of the

amplifier chain in the signal path.

Figure 5-1: Bench Test Wiring Diagram

Resistance Tests

Perform the resistance checks provided in Appendix A, “Resistance Measurements.”

Correct all wiring errors indicated by the resistance measurements before proceeding.




Power Supply (Drawing 707.50606)

Inverter board 707.50602 and preregulator board 707.50605 work together to provide

+5-, ±15-, and +400-Vdc for the operation of the CAST-V electronics. During the

procedure refer to Figure 5-2, and schematics 707.50600 (Inverter - CAST Power

Supply) and 707.50603 (Preregulator - CAST Power Supply).

Figure 5-2: Block Diagram of the Cast-V Power Supply




Setup Procedure

Remove screws, and loosen the boards from the chassis to provide easy access for

adjustments. The setup procedure requires that power be applied to the tool,

measurements be made at various places on the boards, FA resistors be set, and the

boards be reinstalled in the electronics chassis.

WARNING Do not operate the power supply with a short on any of the outputs.The input filter capacitor serving that output may overheat, swell,and possibly burst.

Note Determine the location of capacitors C9, C10, and C11 on the inverter board

before powering up the tool. If excessive operating current is detected (in excess of

250 mA at 120-Vac input), or if C9, C10, or C11 are self-heating, kill power

immediately (the self-heating is from excessive ripple current, not faulty parts).

Disconnect the tool electronics from the power supply by unplugging the connector from

J1. Connect the CAST load box (Figure 5-3) to connector Jl and the CAST-V wiring

harness to provide a load until power supplies are adjusted.

+15

R3 R5R4

R2

R1

J1-20J1-20

J1-19J1-19

J1-18J1-18

J1-17J1-17

J1-16J1-16

J1-15J1-15J1-14J1-14

J1-13J1-13

J1-12J1-12

J1-11J1-11

J1-10J1-10

J1-9J1-9

J1-8J1-8

J1-7J1-7

J1-6J1-6

J1-5J1-5

J1-4J1-4

J1-3J1-3

J1-2J1-2

J1-1J1-1 P2-1 P2-1

P2-2 P2-2

P2-3 P2-3

P2-4 P2-4

P2-5 P2-5

P2-6 P2-6

P2-7 P2-7

P2-8 P2-8

P2-9 P2-9

P2-10 P2-10

P2-11 P2-11

P2-12 P2-12

P2-13 P2-13

P2-14 P2-14P2-15 P2-15

P2-16 P2-16

P2-17 P2-17

P2-18 P2-18

P2-19 P2-19

P2-20 P2-20+400

+5

-15

PowerSupplyBoards

Tool

WiringHarness

COMPONENT PART NUMBER SOURCE

R1, R2 40 K VPR10F(40K) - ND DIGIKEYR3 5 OHMS VPR10F(5.0) - ND DIGIKEY

R4, R5 50 OHMS VPR10F(50) - ND DIGIKEYP2 .76909 HALLIBURTON

J1 .76900 HALLIBURTON

Figure 5-3: Load Resistances for Power Supply Testing




Power Supply Adjustment

Use the following steps to adjust the power supplies:

1. Apply power to the tool by turning up the variable transformer. Monitor the dc

voltage at the positive lead of C2 (chassis-mounted) as the variable transformer is

adjusted. Set the voltage to approximately 92-Vdc.

2. Use an oscilloscope to observe the waveforms at either end of R14 and R15 on theinverter board. A square wave should be present at each part. If the duty cycle is not

close to 50%, the current limiter (sense circuit across R16) may have problems.

3. Check the temperature on capacitors C9, C10, and C11 (just touch them lightly with

your finger). They should be cool. If any noticeable heating is occurring, then there

is an excessive current drain on the output filtered by that capacitor. If any self-

heating is evident, troubleshoot the short before proceeding.

4. Set the frequency of the square wave at R15 to between 18 and 20 kHz by adjusting

R7.

5. Check the waveform at the drains of Q2 and Q3. Each drain should show a square

wave of approximately 140 to190 V peak, with the negative edge at near ground

potential. The peak amplitude voltage becomes more predictable after setup is

complete.

6. On the preregulator board, connect a digital voltmeter to U1-8. Clip R-box across

R16, and adjust R16 to get exactly 10-Vdc at U1-8. Install a 1% RN55 resistor

(nearest value to the R-box reading) in the R34 position on the board. If zener CR11

voltage is near specification limit (>6.5-Vdc), R16 may be adjusted as well to get

exactly 10-Vdc out. If CR11 does not regulate between 6.15- to 6.78-Vdc, replace it.

7. Connect a voltmeter to the +5-Vdc output. A convenient point for this is the 5-V

turret terminals at the uphole end of the I beam part of the tool chassis. On the

preregulator board, connect the R-box across R12, and adjust to set voltage to

5 ±0.05 Vdc. Install a 1% RN55 resistor (nearest value to the R-box reading) in theR13 FA position on board.

8. Measure the voltage at the CR17 cathode (chassis-mounted zener). The voltage

should be 82 ±4 Vdc (not a specification, just a check of normal operation).

9. Vary the output voltage of the variable transformer from 100- to 140-Vac while

watching the +5-Vdc output level. The +5-Vdc output should change less than

0.05 V with any input voltage in the specified range.

10. Measure the voltage at the +15-Vdc output (the +15-V chassis terminal is

convenient). Voltage should be between +15- and +15.7-Vdc. This voltage is not

regulated with precision, and drops with increasing temperature.

11. Measure the voltage at the -15-Vdc output (the -15 V chassis terminal is convenient).Voltage should be between -15- and -15.7-Vdc. This voltage is not regulated with

precision and drops with increasing temperature.

12. Connect the voltmeter to the +400-V terminal on the chassis. Use the preregulator

board FA R27 (nominal 120 k Ω) to adjust the voltage to 400 ±4-Vdc.

Turn off the tool, remove the test load circuitry, and reconnect the power supply to the

chassis electronics.




Parallel/Serial RTU-B Board (Drawing 3.85601)

Setup Procedure

1. Install termination resistor R1 according to the instructions on electronics chassis

assembly drawing 707.55595 (or 707.55567, if modifying a DITS CAST).

2. Configure board jumpers JMP1-JMP4 as follows:

• JMP1 — short pin 2 to pin 7

• JMP2 — unused

• JMP3 — short pin 1 to pin 14, short pin 3 to pin 12, short pin 6 to pin 9, short

pin 7 to pin 8

• JMP4 — short pin 1 to pin 8

3. Copy the CAST-V PC monitor program (CMON.EXE) into the PC to be used for

troubleshooting. From the DOS prompt, type “CMON.EXE” to run the program. The

main menu is displayed on the screen. For operating instructions, refer to

Appendix B, “CAST-V PC Monitor Program.”

4. Apply 120-Vac instrument power to the CAST-V electronics chassis.

5. From the main menu of the monitor program, type any key to begin the 1553

communication with the CAST-V.

Troubleshooting

1. If the monitor program displays error message “DITS ERROR 9,” the PC does not

recognize the 1553 bus adapter. Check for proper installation of the 1553 bus adapter

and proceed.

2. If the monitor program displays error message “DITS ERROR 8,” 1553 buscommunication with the CAST-V has not been established. Ensure that 120-Vac has

been applied to the tool. If 120-Vac is present, make sure that all tool dc power

supplies (+5, ±15, and +400 V) are functioning properly. If all supply voltages are

correct, then either the RTU-B board is bad, or something is wrong with the wiring

between the RTU-B and V40 CPU boards.

3. After 1553 communication has been established, there are no error messages and the

monitor program updates the screen with scan data.

Note Until the motor is spinning, the CAST-V does not update new scans, and the

monitor program only writes zeros to the screen.




R-to-D Board (Drawing 707.55561)

Setup Procedure

Apply 45 Vdc motor power to CAST-V electronics chassis. At this time, the scanner

head spins at around 5.0 rps. If the V40 CPU board is working, the motor speed is

echoed to the Mtr Speed parameter on the monitor screen. If the scanner head is notturning properly, then proceed to the following section “Troubleshooting.” Otherwise,

continue with board checkout.

1. Using an oscilloscope, make sure that the onboard oscillator at J2-4 (REFA) is

providing a sine wave of approximately 4-V p-p at 5 kHz. If the oscillator is set

properly, proceed to Step 2.

2. While the motor is spinning, monitor pins J2-5 (COS) and J2-7 (SIN). These signals

have an amplitude and phase that vary with the position of the motor armature. These

signals should be similar and should be sinusoidal in shape. If they are not, the

problem lies either in the wiring harness between the lower tool connector and the

board or within the scanner assembly. If the signals look good, go to Step 3.

3. With the scanner head spinning, monitor pins J1-8 (TACH/REF) and J1-15

(START). When the face of the transducer (mounted in the scanner head) passes

through the point on the tool housing corresponding to the DITS BUTTON, a +5-V

pulse occurs at J1-8. If the tool is in openhole mode, there are 200 pulses at J1-15 for

every pulse at J1-8. In cased-hole mode, there are 100 pulses at Jl-15 for every pulse

at J1-8.

Troubleshooting

1. If the scanner head is not spinning (or is cogging as it spins) and the current meter on

the dc power supply is excessively high (>1.0 A), then a transistor (FET) has

probably been blown on the commutator board. Turn off the dc motor power and

proceed to the section, “Commutator Board (Drawing 707.55559).”

2. If the scanner head is not spinning and the tool is not drawing any motor current

(supply current <5 mA), make sure that pin U4-12 has +5 V. If the voltage at this pin

is 0 V, then check for a bad EP310 (U4). If U4 is good, then the V40 CPU has not

properly initialized the R-to-D board. Proceed to the section, “V40 CPU Board

(Drawing 707.55666).”

Commutator Board (Drawing707.55559)

The following tests assume that a scanner with an adjusted resolver transformer isavailable. If the resolver transformer must be adjusted, use procedure 770.00103. The

scanner is used to provide a realistic test for the evaluation of the commutator board and

R-to-D board. If problems are encountered at any step, go to the following

“Troubleshooting” section.




Setup Procedure

1. Turn OFF instrument power to the electronics chassis.

2. Slowly increase the motor power supply until 50-Vdc is reached while observing the

current meter on the Sorenson power supply. Current should be less than 0.005 A.

3. Set the Sorenson to 0-Vdc and turn on instrument power. The monitor program

begins 1553 communication with the tool.

4. Again turn up the Sorenson until the scanner motor begins revolving (probably at

less than 10-Vdc). Current drain from the Sorenson should be under 700 mA. If

current is acceptable, set the Sorenson to 50-Vdc.

5. Using a 10× probe on an oscilloscope, compare the waveform on the drains of Q3,

Q6, and Q9 on the commutator board with those provided in Figure 5-4, trace C.

(Figure 5-4, traces A and B, are gate drive waveforms provided for reference.)

6. Set the Sorenson to 45-Vdc. The monitor program screen indicates approximately

5.0 rps at Mtr Speed (screen updates for motor speed are slow). If the motor seems to

be rotating smoothly, motor current is normal, and the waveforms at the drains of

each FET pair are normal, proceed to the section, “V40 CPU Board (Drawing707.55666).”

Figure 5-4: Waveforms from Commutator Board FET Drains




Troubleshooting

Motor current should be nearly zero with no instrument power. If excessive current is

drawn with no instrument power applied, look for wiring errors first and then for blown

FETs.

For reference, Figure 5-4, trace C, is the drain waveform on an N-FET/P-FET pair.

Figure 5-4, trace A, is the drive waveform to a typical P-FET gate. When the P-FET gate

goes negative, the drain of the P-FET switches to near the supply voltage. Figure 5-4,

trace B, is the waveform for the N-FET gate. The N-FET switches its drain to near

ground whenever the Figure 5-4, trace B, waveform goes positive.

In practice, if the Sorenson current meter shows high current at low voltages, both the

P-FET and the N-FET in a pair may be blown, shorting the motor voltage directly to

ground.

Cogging, dead spots in the rotation, or roughness usually indicates only one blown FET.

The various components that drive the FETs rarely blow.

If the gate drive waveforms are not correct, check the wiring between R-to-D board and

commutator board. If the wiring is correct, ensure that the R-to-D board is generating

gate drive voltages (MOTR_A+, MOTR_A-, MOTR_B+, MOTR_B-, MOTR_C+, and

MOTR_C-) on schematic 707.55561.

V40 CPU Board (Drawing 707.55666)

Testing of the V40 CPU board requires that a scanner be connected to the chassis and

that motor power be applied to rotate the scanner. Ensure that 1553 communication has

been established between the PC and the CAST-V (no DITS errors on the monitor

screen).

Setup Procedure

1. With the scanner rotating, make sure that the Scan ID parameter is incrementing and

that it is a value from 0 to 255. If the scanner is rotating, but Scan ID reads zero, go

to Step 3 to determine if the problem lies with the V40 board or the acquisition

control and DSP board.

2. At 45-Vdc, the scanner rotates approximately 5.0 rps. This value is echoed to the

Mtr Speed parameter on the monitor screen.

Note Motor speed is a slow data channel therefore, it takes a few seconds for the new

motor speed to update to the screen.

3. Check the parameters in Table 5-1 to make sure that the V40 is correctly processingslow-channel data. If any of these parameters are incorrect, the V40 CPU Board is

probably bad. Otherwise, go to Step 4.




Table 5-1: Parameters in the V40 CPU Slow-Channel Data Processing

Parameter Value Description

Tool Mode OPEN Default, openhole mode

Gate Start 30.0 Default, in µs

Casing OD 0 Default, in thousandths

Eff. Radius 0 Default, in thousandths

Wfm. Flag OFF Default

4. With the scanner head spinning, monitor the signal at pin J1-42 with a scope. This

signal is the interrupt to the V40 CPU indicating that a new scan has been acquired.

If there is no signal at this pin or if the frequency of the signal is not equal to one

pulse per scanner rotation, then check the wiring between the V40 CPU board and

the acquisition control and DSP board. Otherwise, there is a problem with the DSP

board.

Slow ADC Board (Drawing 707.55587)

The slow ADC board assembly is mounted at the bottom of the electronics chassis

assembly. Many of the voltages measured by the slow ADC come from the directional

sub through connector P1 on the chassis assembly. The input connections to the slow

ADC are accessed through the breakout box in the 37-pin DITS jumper shown in

Figure 5-1.

The following procedure tests all major board functions. Note that INCL and MAG

readings update rapidly and that Motor V, Motor I, and Temp updates are slower. The

scanner does not have to be rotating for the first of these tests and will only be powered

up for the Motor V and Motor I tests.

Setup Procedure

1. Visually inspect the slow ADC Assembly to ensure that the jumper from J2-3 to

J2-12 is in place.

2. Connect the voltage reference source (Dial-A-Source or equivalent) to the bottom

tool connector, as shown in Figure 5-1.

3. Switch the voltage reference to the inputs as indicated in Table 5-2. At each point,

the monitor program indicates the reference voltage input within the tolerances

indicated in the table. Check each input with positive input voltages first. Then

repeat the test with negative input voltages.




Table 5-2: Slow ADC Voltage Reference

Input Voltage Input Voltage Read

INCLX ±4.00 ±3.98 to 4.02

INCLY ±4.00 ±3.98 to 4.02

MAGX ±4.00 ±3.98 to 4.02

MAGY ±4.00 ±3.98 to 4.02

INCLX ±0.05 ±0.046 to 0.054

INCLY ±0.05 ±0.046 to 0.054

MAGX ±0.05 ±0.046 to 0.054

MAGF ±0.05 ±0.046 to 0.054

4. Connect Dial-A-Source to TEMP lead and set to 1.55-Vdc. The monitor program

reading of Temp should be 100 ±3°C.

5. Set the Sorenson to 50-Vdc. The scanner begins revolving. The monitor programindicates 50- ±2-Vdc at Motor V. The current meter of the Sorenson shows the same

current as is indicated at Motor I ±5%.

Troubleshooting

If the monitor program is not updating new readings from the slow ADC, make sure that

connector P30 is secured to the V40 CPU board at connector J2. If it is, then check for

strobes from the V40 serial port at pin J1-13. If there are not any strobes, the problem is

either the V40 CPU board or the wiring between the slow ADC and V40 CPU boards.

Preamplifier/Fire Board (707.55668)

The transducer setup shown in Figure 5-5 is used to provide realistic signals for test

purposes. Insulate the transducer wires from the water in the bucket. Transducer wires of

2 ft or less are desirable. Transducer wires of up to 6 ft can be used, but longer leads

should be of shielded wire or twisted pair. Lead polarity is not important. The important

aspects of the test setup are:

• repeatable known spacing from transducer to target

• parallel spacing between the face of the transducer and the target

• known thickness of the target




0.300

TARGET

TESTTRANSDUC

1.50

1.50

2.00

Figure 5-5: Stand Test Target Setup (distances in in.)

Connections from the test transducer to the tool are made with clip leads or solder

connections to preamplifier/fire board terminals TP-4 (connected in parallel to J1/P21) or

TP-5 (connected in parallel to J2/P20). Coax connectors P20 and P21 are unplugged

when using the test transducer. Do not connect the test transducer in parallel with the

scanner transducer during testing. Finally, do not make or break connections to the

transducer while the firing circuit is operating. Shorts to ground at the preamplifier/fire

board transducer connections blow the FETs generating the fire pulse.

Setup Procedure

Use the following steps to test the preamplifier/fire board. If problems are encountered at

any step, proceed to the “Troubleshooting” section.

1. Turn power OFF to the motor and electronics chassis assembly.

2. Connect the test transducer to TP-5. Disconnect the coax cable from connector J2.

3. Apply instrument power to the electronics chassis assembly. Apply motor power to

the chassis (30-Vdc is enough). Confirm rotation of the scanner head.

4. Monitor test point TP-2 (FIRE). A +5-Vdc pulse at this pin begins the firing process.

5. Using a 10× probe, examine the waveform at TP-5. The waveform should be similar

to that shown in Figure 5-6. If the waveform is similar, turn off instrument power,

disconnect the test transducer, and reconnect the coax cable from the scanner to J2.

6. Connect the test transducer to TP-4. Disconnect the coax cable from J1. Apply power

to the tool. Confirm rotation of the scanner head.

7. Connect an oscilloscope to TP-1. Positive 5-Vdc pulses should be visible, but occur

less frequently than on TP-2. The pulses at this point occur when the mud-cell firing

circuit is enabled.




8. Using a 10× probe, examine the fire-pulse waveform at TP-4. The waveform should

be similar to that shown in Figure 5-6. (The fire-pulse at TP-4 occurs infrequently,

and is easiest seen using a storage or digital oscilloscope.) If the pulse at TP-4 is

similar to Figure 5-6, turn off instrument power, disconnect the transducer from

TP-4, and reconnect the coax cable to J1.

Testing of amplifier gains on the preamplifier/fire board is done at a later stage (gain

range testing).

Figure 5-6: Fire-Pulse Waveform

Troubleshooting

If there are no pulses at TP-2, make sure that there is activity on pins J5-20 (TACH/REF)and JS-36 (START) of the acquisition control and DSP board. If not, there is either a

wiring problem between the DSP board and the R-to-D board or there is a problem with

the R-to-D board. However, if there is activity on these pins, check for pulses at J5-47

(FIRE) on the DSP board. If there are no pulses, something is wrong with the DSP

board. Correct the DSP board problem and continue with preamplifier/fire board

checkout.




Data Acquisition Board (Drawing 707.41002)

Setup Procedure

1. Connect the digital voltmeter to the positive lead of C29. Adjust measured voltage to

4.00 ±0.02-Vdc using FA resistor R31 (nominal 85 k Ω).

2. Ensure that the scanner head is spinning and that the measurement transducer is

firing properly within its test fixture. Using a scope probe, monitor pin U10-28. This

is the input to the 8-bit ADC (MP7684).

3. Refer to Appendix B for the following discussion. If the Tool Mode parameter on the

PC monitor screen is set to OPEN, then the tool is in openhole mode and the signal

at U10-28 (as seen on the oscilloscope) looks similar to Figure B-2 (Appendix B).

The transit times are not the same because the target distances are different, but the

signal character is similar. If there is no acoustic signal or if the waveform does not

look right, proceed to “Troubleshooting.” Otherwise, go to Step 4.

4. Switch into waveform mode by typing . The Wfm. Flag parameter should be ON.

If the waveform on the lower portion of the monitor screen looks similar to thewaveform in Figure B-2, then the digitized waveform is transferred properly from the

data acquisition board to the acquisition control and DSP board. If not, proceed to

“Troubleshooting.” Otherwise, disable waveform mode (by typing ), and go to

Step 5.

5. Switch to cased-hole mode by typing and entering . If the Tool Mode parameter

is set to CASED, then the tool is in cased-hole mode and the signal at U10-28 (as

seen on the oscilloscope) looks similar to Figure B-3. If there is no acoustic signal or

if the waveform does not look right, proceed to “Troubleshooting.” Otherwise, go to

Step 6.

6. Switch to waveform mode by typing . The Wfm. Flag parameter should be ON. If

the waveform on the lower portion of the monitor screen looks similar to the

waveform in Figure B-3, then disable waveform mode (by typing), and proceed to

the section :Acquisition Control and DSP Board (Drawing 707.55665).” However, if

the waveforms are not similar, go to “Troubleshooting.”

Troubleshooting

Disconnect coax connector P17 from the data acquisition board. Check connector P18 on

the preamplifier/fire board for acoustic signal. If there is no signal, the problem lies in

the preamplifier/fire board. Otherwise, the problem lies either in the data acquisition

board or in the wiring between the preamplifier/fire and data acquisition boards.




Acquisition Control and DSP Board (Drawing 707.55665)

To successfully reach this point in the test procedure, most of the electronics and

firmware on the acquisition control and DSP board must be working properly. The

amplitude and transit time values need to be checked to guarantee a good measurement.

Setup Procedure1. Ensure that the scanner head is spinning and that the measurement transducer is

firing properly within its test fixture.

2. Refer to Appendix B during the following discussion. Make sure that the tool is in

openhole mode by typing and entering . When the Tool Mode parameter is set to

OPEN, switch to waveform mode by typing. If the waveform on the lower portion

of the monitor screen is similar to the waveform in Figure B-2, then the DSP

firmware is gain-ranging the acoustic signal.

3. A crosshair is displayed on the monitor screen at the location of the transit time pick.

This crosshair coincides with the onset of the reflected acoustic signal. If the

crosshair is moving around by more than four or five samples, then check forexcessive baseline noise (>30 mV) caused by the analog electronics. Correct the

noise problem, and go to Step 4.

Note The transit time pick MUST be stable to guarantee a good log. Otherwise, the

DSP firmware is not consistently picking on the same portion of the waveform.

4. Disable waveform mode (by typing ), and note the transit time value for the first

shot of scan data (refer to Appendix B, Figure B-4). This value is displayed in

hexadecimal format and must be converted to decimal counts. Convert a transit time

value from counts to actual time units (µs) using the following equation.

Transit time counts × 0.2 µs/ count = transit time

The calculated transit time value for the first shot of scan data is echoed to the Shot 1 DT

parameter on the monitor screen. Using the Figure 5-5 test setup as an example, transit

time is 255 counts.

255 counts × 0.2 µs/ count = 51 µs

A transmit time of 51 µs should be echoed at Shot 1 DT. The speed of sound in water

(for round trip travel) is approximately 34 µs/in. Therefore,

51

inin.

µ

µ

s

s3415

/ ..=

A distance of 1.5 in. is consistent with the distance from the transducer to the test target.

5. Switch the tool to cased-hole mode by typing and entering . When the Tool Mode

parameter is set to CASED, switch to waveform mode by typing . If the waveform

on the lower portion of the monitor screen is similar to the waveform in Figure B-3,

then the DSP firmware is gain-ranging the acoustic signal.

6. Disable waveform mode by typing . Note the transit time value for the first shot of

scan data as in Figure B-5 (Appendix B). This value is identical to the transit time

pick for the openhole mode.




Gain-Range Testing

The following procedure tests the gain-ranging function of the acquisition electronics.

The amplifier stages can be found on the preamplifier/fire and data acquisition boards.

The switching of amplifiers is controlled by the acquisition control and DSP board.

Use the test setup in Figure 5-7 for the gain-range tests.

If a 10-dB/step attenuator is used with a 1-dB/step attenuator to get the necessary 3-dBsteps, connect the two attenuators in series.

The procedure includes a complete test of the scanner transducer channel. The mud-cell

channel is only tested at two input levels, and the levels are chosen to test the

components on the preamplifier/fire board not common to the scanner transducer.

Test Procedure

1. With instrument power disconnected, connect the apparatus as shown in Figure 5-7.

Connect the attenuator output to TP-5 on the preamplifier/fire board with the J2 coax

disconnected. Connect the attenuator ground near the preamplifier/fire board.

2. Remove FET driver chip U4 (D469A) from the preamplifier/fire board.

3. Apply instrument and motor power (30-Vdc) to the CAST-V electronics chassis. The

scanner is rotating.

4. From the main menu of the monitor program, type any key to begin the 1553

communication with the CAST-V.

5. Observe the Shot 1 Pk parameter on the monitor screen. Set the generator to 500

kHz. Set the attenuator to 0 dB, and adjust the signal generator until Shot 1 Pk reads

“4.0XXX volts,” where X reflects a “doesn't care” status.

6. Increase attenuation in -3-dB steps (decreasing signal amplitude), and take readings

from Shot 1 Pk on the monitor screen. Enter the values in Table 5-3 and compare thevalues to tolerance limits. When a -10-dB step is required, always set the 1-dB

attenuator first.

Example: When changing from -12 to -15 dB, first change the 1-dB attenuator from -12

to -5 dB. Then, increase the 10-dB attenuator from 0 to -10 dB.




SINE WAVESIGNAL

GENERATOR50 OHM

50 OHMATTENUATOR

ACVOLT METER

AC INSTRUMENTPOWER SOURCE

PREAMP / FIREBOARD

PERSONALCOMPUTER WITHDITS CARD ANDMONITOR PROG.

TP5

TP4

J2

J1

D469

HYBRID

Figure 5-7: Gain Test Setup

7. Set the attenuator to provide 60 dB of attenuation. Decrease attenuation in 3-dB steps

(increasing signal amplitude) and take readings from Shot 1 Pk on the monitor

screen. Enter the Shot 1 Pk values in Table 5-4.

8. Turn OFF tool power. Disconnect the generator from TP-4. Reconnect the coax to

J2.

9. Disconnect the coax from J1. Connect the attenuator output to TP-5. Apply

instrument and motor power. The test setup is now connected to test the mud-cell.

(The update rate on the mud-cell is slower than on the scanner transducer, but only

two points need to be checked.)

10. Set the attenuator to 0-dB attenuation (Do not recalibrate generator output. Use the

same output level as in Step 5). Enter the Mud Pk voltage in Table 5-5.

11. Set the attenuator to -60 dB. Enter the Mud Pk voltage in Table 5-5.

12. Turn OFF power and disconnect the attenuator from the preamplifier/fire board.

Reconnect the coax to connector J1.

13. Check all readings against the limits provided in Tables 5-3 through 5-5. If all

readings are within limits, gain testing is complete. Reinstall D469 into the U4

socket.




Table 5-3: Gain Test, Increasing Attenuation and Decreasing Amplitude

Step Gain (dB)

Nominal Peak V

Minimum Peak V

Maximum Peak V

Shot 1 Pk Voltage

0 0 4.0000 4.0000 4.0000

1 -3 2.8284 2.5456 3.1113

2 -6 2.0000 1.8000 2.20003 -9 1.4142 1.2728 1.5556

4 -12 1.0000 0.9000 1.1000

5 -15 0.7071 0.6364 0.7778

6 -18 0.5000 0.4500 0.5500

7 -21 0.3536 0.3182 0.3889

8 -24 0.2500 0.2250 0.2750

9 -27 0.1768 0.1591 0.1945

10 -30 0.1250 0.1125 0.1375

11 -33 0.0884 0.0795 0.0972

Table 5-4: Gain Test, Decreasing Attenuation and Increasing Amplitude

Step Gain (dB)

Nominal Peak V

Minimum Peak V

Maximum Peak V

Shot 1 Pk Voltage

12 -60 0.0039 0.0035 0.0043

13 -57 0.0055 0.0050 0.0061

14 -54 0.0078 0.0070 0.0086

15 -51 0.0110 0.0099 0.0122

16 -48 0.0156 0.0141 0.017217 -45 0.0221 0.0199 0.0243

18 -42 0.0313 0.0281 0.0344

19 -39 0.0442 0.0398 0.0486

20 -36 0.0625 0.0563 0.0688

21 -33 0.0884 0.0795 0.0972

22 -30 0.1250 0.1125 0.1375

23 -27 0.1768 0.1591 0.1945

Table 5-5: Gain Test, Mud-Cell Channel

Attenuator Setting

Nominal Peak V

Minimum Peak V

Maximum Peak V

Mud Pk Voltage

0 dB 4.0000 3.5000 4.3000

-60 dB 0.0039 0.0035 0.0043




Heat Test and QC Data Collection

Collection of data for QC files and heat testing requires that the electronics chassis

assembly be placed in a Dispatch oven, while connected as shown in Figure 5-8. After

confirming correct tool function, ambient data readings for both cased-hole and openhole

mode are entered into the form provided. The chassis assembly is then heated to 350°F

and soaked for 1 hour, and elevated temperature readings are entered into the form

provided. Data are then evaluated, and a final inspection is given to the tool.

Procedure

1. Place the electronics chassis assembly in the Dispatch oven. Sleeve the chassis

assembly, or place it in the oven to prevent hot spots on the tool chassis. Connect a

thermocouple digital temperature gage to the chassis.

2. Collect data to fill the “Ambient” columns on the data sheet provided.

3. Heat the oven to 350°F, and hold for 1 hour.

4. Collect data to fill the “350°F” columns on the data sheet provided.

5. Compare all readings to ensure that temperature drift is within the limits provided.

6. Terminate the oven test, and allow the chassis to cool to ambient temperature.

7. Carefully inspect the tool for heat-induced damage. (Be sure to check the capacitors

in the power supply for signs of swelling or leakage.)




CAST-V HEAT TEST DATA

TOOL SERIAL No.

Variable Ambient Cased-

Hole

Ambient Open Hole

350 ° F Cased-Hole

350 ° F Openhole

Normal Tolerance

Shot 1 DT

(µs)

±1 µs

Shot 1 Pk

(V)±10%

Motor V

(V)

±10%

Motor I

(A)±10%

Scan ID

Counting?

Yes/No

Mud DT ±10%

+5-Vdc ±100 mV

+15-Vdc +0/-1-Vdc

-15-Vdc -0/+1-VdcINCLY

1Good/Bad

400-Vdc ±10-Vdc

1 If the directional sub is connected in the test setup, rotate the sub to get the INCLY

reading to near 0-Vdc out. Record voltages, but only look for an obvious failure.

ATTACHMENTS:

1. Screen prints of cased-hole and openhole waveforms taken at ambient temperature.

2. Screen prints of cased-hole and openhole waveforms taken at 350°F.

TECHNICIAN NAME DATE OF TEST




Dial-A-SourceVoltage ReferenceBreak-out

Box

ClipLead 0 to 150 vdc at 1.5 amp

Sorenson Power Supply

Dispatch oven containingelectronics chassis Assembly

Isolated ACpower source

Transducer in

water-filledtest fixture

Personal computer withDits Exerciser card

installed

Directional sub(optional)

ScannerMud cell pointed upand filled with water

Figure 5-8: Oven Test Setup




07/97 770.00696-NW References 6-1

References

IntroductionThis section contains reference material and information about the DITS CAST tool

upgrade to the CAST-V.

ManualsThe following manuals are available as references for the CAST-V:

• CAST-V Field Operations Manual - Image Mode, 770.00700

• CAST-V Field Operations Manual – Cased Hole, 770.00709

• CAST-V Engineering Documentation Package, 770.00710

DITS CAST Tool Upgrade to the CAST-VDITS CAST tools upgraded to the CAST-V configuration require power supply board

assembly, 707.50606, to be modified. This procedure explains how to modify the DITS

CAST power supply to obtain the higher output voltages required by CAST-V. The

higher output voltages are necessary to ensure proper operation of the motor drive

circuitry at elevated temperatures.

Reference Drawings• DITS CAST to CAST-V Electronics Chassis Modification, 707.55567

• Power Supply PC Board Assembly, 707.50606

• Toroid Transformer, 707.50607

• Inverter PC Board Assembly, 707.50602

• Preregulator PC Board Assembly, 707.50605

Section

6



6-2 References 770.00696-NW 07/97

General Information

CAST-V tools use a toroid transformer, P/N 707.50607, revision B, that has a different

winding structure than the toroid transformer previously used on DITS CAST tools. The

DITS CAST toroid transformer, P/N 707.50607, revision NW, must be replaced with a

revision B transformer or modified by adding additional windings to the existing

transformer. Additional changes to the power supply circuitry are necessary to

compensate for replacement or modification of the transformer. After completion of thisprocedure the output of the ±15-Vdc increases from 14.5- to 15.5-Vdc.

Transformer Identification

The vendor identifies toroid transformer 707.50607 by serial numbers as follows:

• revision NW is serial numbers 001 through 045

• revision A was never manufactured

• revision B is serial numbers 046 and up

Upgrade Procedure

1. Remove the power supply board assembly from the electronics chassis, and locate

the toroid transformer 707.50607 on inverter board 707.50602.

2. Remove the nut and washer from the mounting screw retaining the transformer to

the PC board. Unthread the screw from the Teflon cone, and remove it from the

board. Save all hardware.

3. Carefully remove the transformer from the PC board, and remove as much RTV as

possible without damaging the transformer.

Note If transformer 707.50607, revision NW, is now replaced with 707.50607, revisionB, then proceed directly to Step 6.

4. Using 24 AWG Teflon insulated wire (P/N .83489), make two windings, each with

one turn (see Figure 6-1). It is not necessary to tape the new windings to the core.

When mounted to the board, the transformer mounting cone and RTV adequately

secure the wire windings. The added windings also do not overlap where the

mounting cone could crush the insulation and short the wires.



07/97 770.00696-NW References 6-3

Note:"One turn" on a toroid requires that the wire pass through the center hole of the toroid only once.

Positioning of the wire around the toroid perimeter is not important.

Figure 6 -1: Toroid Winding

5. Referring to Figure 6-2, make the added turn connections. If connected correctly, the

voltage from the added turns add to the voltage from W5 and W6 on transformer

707.50607. The peak-to-peak voltage at turret 4 is 2 V higher than the peak-to-peak

voltage at the junction of the added turn at WHT/RED. Similarly the peak-to-peak

voltage at terminal 8 will be 2 V higher than the peak-to-peak voltage at the added

turn at WHT. The ±15-Vdc outputs each increase to approximately 15.5-Vdc.

6. Reattach the transformer to the PC board using the original hardware.

7. Replace resistors R20, R21, and R32, located on preregulator board 707.50605, as

indicated below.

• R20. Replace P/N .73379 (15K, 3W) with P/N .02168 (10K, 3W).

• R21. Replace P/N .73379 (15K, 3W) with P/N .02168 (10k, 3W).

• R32. Replace P/N .73608 (5K, 3W) with P/N .25193 (6.2K 3W).



6 -4

R ef er en c e

s

7 7

0 . 0 0 6 9 6 -NW

0 7 / 9 7

F i g ur e 6 -2 : Wi r i n g of M o d i f i e d T

r an sf or m er




07/97 770.00696-NW Resistance Measurements A-1

Resistance Measurements

IntroductionThis appendix provides preventive maintenance (PM) measurement criteria for the

CAST-V electronics chassis.

Downhole End Resistance Measurements

Table A -1: Downhole End Resistance Measurements

From To Read Scale Items Checked

(Note 1) (Note 2)

1 Chassis Short RX1 Ground for scanner transducer

2(±) Chassis 2.4-2.7 k Ω RX100 Scanner Xducer signal (slight diode

effect)

3(±) Chassis >4 k Ω Rx100 Slow ADC ID input

4 - 6 Chassis Short RX1 Chassis ground connection

7(±) Chassis 2.4-2.7 k Ω RX100 Mud transducer signal (slight diode effect)

8 Chassis Short RX1 Chassis ground connection

9 Chassis Short RX1 Ground for mud transducer



12 - 13 N.C.

14(+) Chassis 15-20 k Ω RX100 Resolver sine (diode effect)

14(-) Chassis 7.5-10 k Ω RX100 Resolver sine (diode effect)

15(+) Chassis 15-20 k Ω RX100 Resolver cosine (diode effect)

15(-) Chassis 6-8 k Ω RX100 Resolver cosine (diode effect)

16(+) Chassis 50-120 RX1 5-Vdc power (large diode effect)

16(-) Chassis <10 RX1 5-Vdc power (large diode effect)

17(+) Chassis 2600 RX100 +15-Vdc power (large diode effect)

17(-) Chassis 470 RX100 +15-Vdc power (large diode effect)

Appendix

A



A-2 Resistance Measurements 770.00696-NW 07/97

Table A-1: Downhole End Resistance Measurements (concluded)


(Note 1) (Note 2)

18(+) Chassis 480 RX100 -15-Vdc power (large diode effect)

18(-) Chassis 2200 RX100 -15-Vdc power (large diode effect)

19 N.C.

20 Chassis Short RX1 Resolver shield21(±) Chassis 2.5-6 k Ω RX100 Ref A - Res. Drv. Signal (slight diode

effect)

22 Chassis Short RX1 Resolver Gnd

23 N.C.

24 Chassis 70-90 k Ω RX10K Input to slow ADC






30-34 N.C.35 (-) Chassis <10 RX1 FET body diode in commutator bd. Q2

36 (-) Chassis <10 RX1 FET body diode in commutator bd. Q5

37 (-) Chassis <10 RX1 FET body diode in commutator bd. Q8

35 (+) Chassis >3000 RX100 FET body diode in commutator bd. Q2



35 (+) Pin 13

Uphole

<100 RX1 FET body diode in commutator bd. Q3

36 (+) Pin 13

Uphole


37 (+) Pin 13Uphole


35 (-) Pin 13

Uphole

>3000 RX100 FET body diode in commutator bd. Q3

36 (-) Pin 13

Uphole


37 (-) Pin 13

Uphole


NOTE 1: The sign in parentheses indicates polarity of meter lead connected to test point.

NOTE 2: All readings taken with a Simpson 260. Different brands of meters show different

resistances in checking nonlinear circuits, that is, circuits with diodes present.



07/97 770.00696-NW Resistance Measurements A-3

Uphole End Resistance Measurements

Table A -2: Uphole End Resistance Measurements


(Note 1) (Note 2)

1 2 55 RX1 DITS transformer and line resistors3 N.C.

4 Chassis Open (DITS shield)

5 - 12 N.C.

13 14 5 - 7 RX1 Power transformer continuity

13 (-) Chassis 10-30 RX1 Mot. switching FET body diodes turned on

13 (+) Chassis 1.5-2.0 k Ω RX100 Mot. switching FETs turned off. (large

capacitor charge time)

14 (-) Chassis 10-30 RX1 Mot. switching FET body diodes turned on

14 (+) Chassis 1.5-2.0 k Ω RX100 Mot. Switching FETs turned off. (large

capacitor charge time)

15 N.C.16 19 5 - 7 RX1 Power transformer continuity

16 Chassis 3 - 5 RX1 Auxiliary power connection to chassis

17 N.C.

18 N.C.

19 Chassis 3 - 5 RX1 Auxiliary power connection to chassis

NOTE 1: The sign in parentheses indicates polarity of meter lead connected to test point.

NOTE 2: All readings taken with a Simpson 260. Different brands of meters show different

resistances in checking nonlinear circuits, that is, circuits with diodes present.




07/97 770.00696-NW CAST-V PC Monitor Program B-1

CAST-V PC Monitor Program

IntroductionThis C language program serves as a mechanism for sending tool commands and

monitoring tool data without a surface system. The communication scheme between the

CAST-V and the PC is 1553 Manchester.

Required Equipment• 386 or higher microprocessor

• VGA or higher monitor

• 1553 bus adapter 3.35000

• CAST-V PC Monitor Program - CMON.EXE (707.55634)

OperationTable B-1 describes the tool commands available to the user (refer to Figure B-1).

Table B-1: Tool Commands of the CAST-V PC Monitor Program

Command Description

Switches tool modes in the CAST-V. Select OPEN for openhole mode

and CASED for cased-hole mode. The tool echoes its current mode of

operation to the Tool Mode parameter on the monitor display.

Toggles the CAST-V between sending scan data and waveform data.

When the tool is sending scan data (default), the Wfm. Flag is OFF, and

scan data is displayed on the lower portion of the screen. When the tool

is sending waveform data, the Wfm. Flag is ON, and 128 µs of

waveform is displayed on the lower portion of the screen.

Defines the start point of the scan data display. This number is the offset

in words into the scan data from the fire-pulse.

Appendix

B



B-2 CAST-V PC Monitor Program 770.00696-NW 07/97

Table B-1: Tool Commands of the CAST-V PC Monitor Program (concluded)

Command Description

Sets the start position in counts1 of the gating function in the acquisition

electronics. All digital processing on the transducer signal begins at this

location in the waveform.

Sends the casing OD in thousandths of an inch, to the CAST-V for use

by the thickness algorithm. The casing OD is echoed to the Casing OD

parameter on the monitor display.

Sends the effective tool radius in thousandths of an inch, to the CAST-V

for use by the thickness algorithm. The effective tool radius is echoed to

the Eff. Radius parameter on the monitor display.

Pauses the display and the 1553 communication with the CAST-V.

or Help. Displays the help command menu.

Quit.

1 1 Count = 0.2 µs




CAST-V PC Monitor Program (707.55634 -.NW)

Commands:

m

t

s

g

ce

Spacebarh,?

q

Set Tool Operating Mode (OPEN/CLOSED)

Toggle Waveform Display Mode (ON/OFF)

Set Data Display Start Point

Set Gate Start Position

Set Casing OD

Set Effective Tool Radius

Pause displayHelp. Display this Menu.

Quit

Refer to CAST-V Electronics Assy Test Procedure (770.10511) for detailedoperating instructions.

TYPE ANY KEY TO CONITINUE

Figure B-1: PC Monitor Program Main Menu

After a command is sent to the tool, the command information is echoed to the bottom of

the monitor display in the following format (refer to Figure B-2):

Command sent- X Y,

where:

X is the command sent to the tool in hexadecimal format

Y is the corresponding data in decimal format.




Scan ID

Mtr Speed (rps)

Tool Mode

Gate Start (us)

Casing O.D.

Eff. RadiusVersion

Wfm. Flag

163

5.1

OPEN

30.0

0

0C

ON

INCLX (V)

INCLY (V)

MAGX (V)

MAGY (V)

Motor V (V)

Motor I (A)Temp (Deg C)

-3.156

-3.210

-1.883

-2.704

0.277

-0.006-1566.258

Mud Pk

Mud Pk Gain

Mud DT (us)

Mud Sum

Mud Sum Gain

Mud Target TkAzimuth (Deg)

Wfm. DT (us)

0

0

0.0

0

0

0235.1

53.8

Command sent- F6 150

10 us./div.

COMMAND ECHO

PEAK AMPLITUDE

TRANSIT TIME PICK

Figure B-2: Waveform Data for Openhole Mode

Interpretation:

Critical tool parameters are displayed in the top portion of the monitor display.

Table B-2 describes each parameter.




Table B-2: Tool Parameters of the CAST-V PC Monitor Program

Parameter Description

Scan ID Number of current scan. An incrementing Scan ID value (0 to 255) is

an indication that the 1553 communication is still active and that the

CAST-V is updating new scan data to the surface.

Mtr Speed Speed in rps of the spinning scanner head. This value is useful in

determining whether or not the head is rotating at the correct speed.

In cased-hole mode, this value should not exceed 10.0 rps (downhole

processing limitation). In openhole mode, this value should not

exceed 15.0 rps (telemetry limitation).

Tool Mode Current operating mode (OPEN/CASED). OPEN (default) indicates

that the tool is in the openhole mode. CASED indicates that the tool

is in the cased-hole mode.

Gate Start Start position of the gate in µs for the digital processing of the

transducer signal.

Casing OD Outside diameter of the casing. This parameter is needed by theCAST-V firmware as input to its thickness algorithm. The casing OD

in thousandths of an inch, is echoed from the tool to this screen

location.

Eff. Radius Effective spinning radius of the transducer from the centerline of the

tool housing. This parameter is needed by the CAST-V firmware as

input to its thickness algorithm. The effective radius in thousandths

of an inch, is echoed from the tool to this screen location.

Version Current number of the CAST-V firmware.

Wfm. Flag Waveform mode flag. This parameter is ON when the waveform

mode is enabled and OFF when waveform mode is disabled.

INCLX Raw voltage measured by the slow ADC board of output from the x-

coordinate of the inclinometer.

INCLY Raw voltage measured by the slow ADC board of output from the y-

coordinate of the inclinometer.

MAGX Raw voltage measured by the slow ADC board of output from the x-

coordinate of the magnetometer.

MAGY Raw voltage measured by the slow ADC board of output from the y-

coordinate of the magnetometer.

Motor V DC voltage supplied to the commutator board. This value is echoedfrom the tool and differs from the Sorensen voltage meters whenever

cable resistance is present.

Motor I DC current drawn by the scanner motor. This value is echoed from

the tool and should be equivalent to the value seen at the Sorensen

supply within a few mA.

Temp Temperature in °C within the directional sub housing.

Table B-2: Tool Parameters of the CAST-V PC Monitor Program (concluded)




Parameter Description

Shot 1 Pk Gain-recovered amplitude in volts for the first shot of scan data. This

is the amplitude of the signal measured at the transducer. This value

is not displayed in waveform mode.

Mud Pk Gain-recovered amplitude (in volts) for the mud cell. This is the

amplitude of the signal measured at the transducer. This value is notdisplayed in waveform mode.

Mud Pk Gain System gain in 3-dB steps for the peak window of the mud-cell

transducer.

Mud DT Delta-T (or transit time) pick for the mud-cell transducer. Distance

from the mud-cell to the target is approximately 1.25 in.

Mud Sum Sum value within the resonance window of the mud-cell transducer.

This value is not gain recovered.

Mud Sum Gain System gain in 3-dB steps for the resonance window of the mud-cell

transducer.

Mud Target Measured thickness in thousandths of an inch, of the mud-cell target.

The mud-cell target is 0.3 in. thick.

Azimuth Clockwise angle in degrees from the DITS button to magnetic north.

This value is calculated from the raw voltages of MAGX and

MAGY.

Shot 1 DT Transit time in µs for the first shot of scan data. This value is not

displayed in waveform mode.

Wfm. DT Transit time in µs of the acquired waveform. This value is only

displayed in waveform mode.

In waveform mode Wfm. Flag is ON, 128 µs of waveform are displayed on the lowerportion of the monitor screen. Mud-cell information is not updated in waveform mode.

Examples of openhole and cased-hole waveforms can be found in Figures B-2 and B-3,

respectively.




Scan ID

Mtr Speed (rps)

Tool Mode

Gate Start (us)

Casing O.D.

Eff. RadiusVersion

Wfm. Flag

196

4.9

CASED

30.0

0

0C

ON

INCLX (V)

INCLY (V)

MAGX (V)

MAGY (V)

Motor V (V)


-1.614

-1.642

-1.271

-1.550

0.207

-0.006-1041.214

Mud Pk

Mud Pk Gain

Mud DT (us)

Mud Sum

Mud Sum Gain


Wfm. DT (us)

0

0

0.0

0

0

0230.6

54.0

10 us./div.

PEAK AMPLITUDE

12.8 Secµ

RESONANCEWINDOW

TRANSIT TIME PICK

Figure B-3: Waveform Data for Cased-Hole Mode

When the waveform mode is disabled Wfm. Flag is OFF, scan data are displayed on the

lower portion of the monitor screen. Scan data are represented as four-digit hexadecimal

values, each value corresponding to one word of raw telemetry. These data have slightly

different formats, depending on the mode of CAST-V operation (OPEN/CASED).

In openhole mode (OPEN), each firing of the measurement transducer produces two

words of telemetry. For instance, the first shot in a scan consists of the first two words;

the second shot consists of the next two words. The first hexadecimal word can be

broken down into bytes. In Figure B-4, byte 1 is the system gain of the peak window in

3-dB steps, and byte 2 is the peak amplitude in raw ADC counts. The second

hexadecimal word (bytes 3 and 4) is the transit time pick in 0.2-µs counts. The data for

the next shot reside at words 3 and 4 (bytes 5 through 8), and the pattern repeats. Inopenhole mode, there are 200 shots per scan.




Scan ID

Mtr Speed (rps)

Tool Mode

Gate Start (us)

Casing O.D.Eff. Radius

Version

Wfm. Flag

160

5.0

OPEN

30.0

00

C

OFF

0

12

24

36

48

60

72

84

96

108

120

132

144

156

952

952

952

952

952

952

952

952

952

952

952

952

952

952

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

952

INCLX (V)

INCLY (V)

MAGX (V)

MAGY (V)

Motor V (V)Motor I (A)

Temp (Deg C)

Shot 1 Pk (V)

-2.181

-2.210

-1.562

-2.000

0.207-0.006

-1236.569

0.90598

Mud Pk

Mud Pk Gain

Mud DT (us)

Mud Sum

Mud Sum GainMud Target Tk

Azimuth (Deg)

Shot 1 DT (us)

0.90598

10

53.0

0

00

232.0

54.0PEAK AMP

GAIN

TRANSIT TIME

Figure B-4: Scan Data for Openhole Mode

In cased-hole mode (CASED), each transducer firing produces four words of telemetry.

In Figure B-5, byte 1 is the system gain of the peak window and byte 2 is the peak

amplitude. The second hexadecimal word (bytes 3 and 4) is the transit time pick. The

third hexadecimal word (bytes 5 and 6) is the sum of the resonance window. Byte 7 is

the system gain of the resonance window, and byte 8 is the thickness step2 of the casing.

The data for the next shot reside at words 5 through 8 (bytes 9 through 16), and the

pattern repeats. In cased-hole mode, there are 100 shots per scan.

2 (Thickness step × 0.002 in./step) + 0.2 in. = casing thickness.



Scan ID

Mtr Speed (rps)

Tool Mode

Gate Start (us)

Casing O.D.

Eff. RadiusVersion

Wfm. Flag

94

4.9

CASED

30.0

0

0C

OFF

0

12

24

36

48

60

72

84

96

108

120

132

144156

957

957

957

957

957

957

957

957

957

957

957

957

957957

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E

10E10E

1132

1132

1132

1132

1132

1132

1132

1132

1132

1132

1132

1132

11321132

1132

1132

1132

1132

1132

1132

1132

1132

1132

1132

1132

1132

11321132

1132

1132

1132

1132

1132

1132

1132

1132

1132

1132

1132

1132

11321132

957

957

957

957

957

957

957

957

957

957

957

957

957957

957

957

957

957

957

957

957

957

957

957

957

957

957957

863

863

871

873

872

86B

867

86F

86B

868

879

86A

874867

86A

865

873

86A

869

877

86C

86C

872

86A

875

877

86C868

86C

866

868

875

86C

869

86E

870

86A

875

86A

870

87586D

INCLX (V)

INCLY (V)

MAGX (V)

MAGY (V)

Motor V (V)


Shot 1 Pk (V)

-2.650

-2.689

-1.746

-2.377

0.277

-0.006-1402.950

0.96122

Mud Pk

Mud Pk Gain

Mud DT (us)

Mud Sum

Mud Sum Gain


Shot 1 DT (us)

0.96122

8

54.6

2910

18

300233.7

54.0PEAK AMP

GAIN

TRANSIT TIME RESONANCE SUM RESONANCE GAIN

THICKNESS STEP

cast-v sm.pdf

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