38860450 repair of computer and video monitors

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  • 8/8/2019 38860450 Repair of Computer and Video Monitors



    Notes on the Troubleshooting and Repair ofComputer and Video Monitors


    Chapter 1) About the Author & CopyrightChapter 2) Introduction2.1) Monitors, monitors, and more monitors2.2) Related Information2.3) Monitor fundamentals2.4) Monitor characteristics2.5) Types of monitors2.6) Why auto-scan?2.7) Analog vs. digital monitors

    2.8) Interlacing2.9) Monitor performance2.10) Performance testing of monitors2.11) Monitor repair2.12) Most Common Problems2.13) Repair or replace

    Chapter 3) Monitors 1013.1) Subsystems of a monitor3.2) For more information on monitor technology3.3) On-line tech-tips databases

    Chapter 4) CRT Basics

    4.1) Color CRTs - shadow masks and aperture grills4.2) Degaussing (demagnetizing) a CRT4.3) How often to degauss4.4) Why are there fine lines across my Trinitron monitor or TV?

    Chapter 5) Monitor Placement and Preventive Maintenance5.1) General monitor placement considerations5.2) Non-standard monitor mounting considerations5.3) Preventive maintenance - care and cleaning5.4) Monitor tuneup?

    Chapter 6) Monitor Troubleshooting6.1) SAFETY

    6.2) Safety Guidelines6.3) Troubleshooting tips6.4) Test equipment6.5) Incredibly handy widgets6.6) Safe discharging of capacitors in TVs and video monitors6.7) Additional information on discharging CRTs6.8) The series light bulb trick6.9) Getting inside a monitor6.10) Specific considerations before poking around inside a TV or monitor

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    Sci.Electronics.Repair FAQ: Notes o...pair of Computer and Video Monitors http://plop.phys.cwru.edu/repairfaq/REPAIR/whole/F_monfaq

  • 8/8/2019 38860450 Repair of Computer and Video Monitors


    6.11) Dusting out the inside of a monitor6.12) Troubleshooting a monitor with the mainboard disconnected

    Chapter 7) Monitor Adjustments7.1) User picture adjustment7.2) Focus adjustment7.3) Brightness and color balance adjustment7.4) Optimal procedure for setting brightness/background and screen adjustments

    7.5) Position, size, and linearity adjustment7.6) Pincushion adjustments7.7) Geometry adjustment7.8) Why is the convergence on my monitor bad near the edges7.9) CRT purity and convergence problems7.10) CRT purity adjustment7.11) CRT convergence adjustment7.12) Tilted picture7.13) Monchrome monitor size, position, and geometry adjustments

    Chapter 8) Low Voltage Power Supply Problems8.1) Low voltage power supply fundamentals

    8.2) Monitor deflection derived power supply faults8.3) Power button on monitor is flakey8.4) Monitor blows fuse8.5) Internal fuse blew during lightning storm (or elephant hit power pole)8.6) Fuse replaced but monitor clicks with power-on but no other action8.7) Power-on tick-tick-tick or click-click-click but no other action8.8) No picture but indications of power8.9) Monitor mostly dead, possible whine from power supply8.10) Reduced width picture and/or hum bars in picture8.11) Dead monitor with periodic tweet-tweet-tweet, flub-flub-flub, low-low voltage8.12) Monitor power cycling on and off

    8.13) Shorted Components8.14) Startup problems - nothing happens, click, or tick-tick-tick sound8.15) Monitor turns off after warming up8.16) Monitor doesn't power up immediately8.17) Old monitor requires warmup period8.18) Monitor shuts down with bright picture or when brightness is turned up8.19) Power supply interactions8.20) Relays in the Power Circuitry of monitors8.21) What is a posistor?8.22) Flameproof Resistors

    Chapter 9) Deflection Problems

    9.1) Deflection fundamentals9.2) Monitor display is off-center9.3) Gross problems in size or position at certain scan rates9.4) Reduced width9.5) Can incorrect or missing video damage my monitor?9.6) Picture squeezed in then died9.7) Horizontal deflection shutting down9.8) Horizontal squashed9.9) Monitor non-linearity

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    Sci.Electronics.Repair FAQ: Notes o...pair of Computer and Video Monitors http://plop.phys.cwru.edu/repairfaq/REPAIR/whole/F_monfaq

  • 8/8/2019 38860450 Repair of Computer and Video Monitors


    9.10) Picture squeezed on both left and right side of screen9.11) Vertical squashed9.12) Keystone shaped picture9.13) Picture size changing9.14) Monitor will not sync9.15) Horizontal lock lost9.16) Insufficient width (without hum bars)

    9.17) Loss of horizontal sync (also applies to vertical) after warmup9.18) Replicated or offset multiple images9.19) Part of picture cut off9.20) Bright or dark bars on edge of picture (horizontal or vertical)9.21) Single Vertical Line9.22) Single Horizontal Line9.23) Intermittent jumping or jittering of picture or other random behavior9.24) Horizontal output transistors keep blowing (or excessively hot)9.25) Horizontal output transistors blowing at random intervals9.26) Vertical foldover9.27) Excessive width/pincushioning problems

    9.28) Uncorrectable pincushion distortion with new monitor9.29) Deflection yoke testing9.30) Deflection yoke repair9.31) Testing of flyback (LOPT) transformers9.32) Picture size suddenly becomes larger (or smaller)9.33) Burning up of various size or centering resistors9.34) Picture shifted horizontally

    Chapter 10) High Voltage Power Supply Problems10.1) HV power supply fundamentals10.2) What is a tripler?10.3) High voltage shutdown due to X-ray protection circuits

    10.4) Low or no high voltage10.5) Excessive high voltage10.6) Snaps, crackles, and other HV breakdown10.7) Arcing, sparking, or corona from CRT HV anode (red wire/suction cup)10.8) Arcing at spark gaps and gas discharge tubes on CRT neck board or elsewhere10.9) Arcing from flyback or vicinity10.10) Dave's complete procedure for repair of an arcing flyback10.11) Spark gaps and gas discharge bulbs on CRT neck board or elsewhere10.12) Arcing due to bad connections to or disconnected CRT return10.13) Flashovers inside the CRT10.14) Ozone smell and/or smoke from monitor

    10.15) X-ray and other EM emission from my monitor?10.16) Should I be worried about X-ray exposure while servicing a TV or monitor?10.17) Flyback got wet10.18) Blooming or breathing problems10.19) Erratic focus or screen (G2) voltage and/or controls on flyback10.20) Focus/Screen divider bypass surgery10.21) Decaying or erratic focus or screen (G2) voltages10.22) Disconnecting focus wire from CRT driver board10.23) Focus or screen voltage drifts after warmup only when CRT is connected

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    Sci.Electronics.Repair FAQ: Notes o...pair of Computer and Video Monitors http://plop.phys.cwru.edu/repairfaq/REPAIR/whole/F_monfaq

  • 8/8/2019 38860450 Repair of Computer and Video Monitors


    Chapter 11) Raster, Color, and Video Problems11.1) Blank picture, power light on, digital controls (if any) active11.2) Brightness control has no effect11.3) No color - black and white picture11.4) One color is too weak or too strong11.5) Psychodelic color11.6) Monitor manufacturing quality and cold solder joints

    11.7) Why can't monitor manufacturers learn to solder properly?11.8) Intermittent, flickering, or missing colors11.9) Some commentary on monitor and TV whacking11.10) Ghosts, shadows, or streaks in picture adjacent to vertical edges11.11) General streaks or lines to the right of bright or dark areas11.12) Washed out picture11.13) Retrace lines in picture11.14) White/gray retrace lines11.15) Red, green, or blue retrace lines11.16) Bad CRT causing retrace lines11.17) Red, green, or blue full on - fog over picture

    11.18) Totally white screen (probably with retrace lines)11.19) Shorts in a CRT11.20) Providing isolation for a CRT H-K short11.21) Rescuing a shorted CRT11.22) Dark picture11.23) Brightening an old CRT11.24) Color balance changes across screen from left to right11.25) Bleeding highlights11.26) Trailing lines in one or more colors11.27) Purity problems with bright pictures11.28) Why does the intensity appear so non-uniform in bright areas?

    11.29) Brightness changes from left-to-right across screen11.30) Picture fades in and out11.31) Occasional brightness flashes11.32) Occasional static, lines, spots, or other unsightly blemishes11.33) Flickering monitor11.34) Excessive brightness and/or washed out picture11.35) Focus problems11.36) Bad focus (fuzzy picture)11.37) Focus drift with warmup11.38) About the quality of monitor focus11.39) Bad focus and adjustment changes brightness

    11.40) Charlie's comments on focus problems11.41) Purple blob - or worse11.42) Color rings - bullseye pattern11.43) Magnet fix for purity problems - if duct tape works, use it!11.44) Color monitor only displays one color11.45) Disappearing Red (or other color)11.46) Interference resulting in jiggling or wiggling11.47) Interference from electrical wiring11.48) Interference from power lines

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    Sci.Electronics.Repair FAQ: Notes o...pair of Computer and Video Monitors http://plop.phys.cwru.edu/repairfaq/REPAIR/whole/F_monfaq

  • 8/8/2019 38860450 Repair of Computer and Video Monitors


    11.49) Interference from cross-connected buildings11.50) Interference from other equipment11.51) My monitor is possessed!11.52) Shimmering image due to vibrations11.53) Wiring transmitted interference11.54) Jittering or flickering due to problems with AC power11.55) My monitor has the shakes

    11.56) Fred's comments on monitor interference problems11.57) Loss of color after warmup

    Chapter 12) Miscellaneous Problems12.1) Contour lines on high resolution monitors - Moire12.2) Moire and shadow mask dot pitch12.3) Interference between monitor and VCR or TV12.4) Cable installed upside-down - now monitor does not sync correctly12.5) Isolated spots on display12.6) Power saving problems12.7) Monitor drift?12.8) Monitor shuts down or goes blank at certain scan rates