tips, guides and reports for people repairing televisions

Tips, guides and reports for people repairing televisions and electronic equipment

TELEYAND HOME ELECTRONICS REPAIROCTOBER 2002 £3.10

IIIRTIV-117111M-1

Panasonic Euro-7 chassisPic -based pattern generatorMemory technologydevelopments 1 1 1

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Satellite, PC, Monitor, TV, VCR and DVD faults

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Can't find the part number!Eldor transformers are easily recognised by theEldor logo shown on the transformer body. TheEldor part number format consists of two sets of 4numbers which may also have an alpha characteras a suffix. (On the example label to the right theEldor part number is 1372.0031C)

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classicTechnical helpline 01635 278678

October 2002 Vol. 52, No. 12

707 CommentThe software bug problem.

708 TeletopicsBlue -laser disc formats. Freeview DTT services.Beko-Grundig link? ITV Digital wound up. Greentax argument. New video products.

710 Memory technologydevelopmentsThe electronics industry may be in recession, butresearch and development continue. RalfBuckstone reports on developments in the memoryfield.

712 A serviceman's guide to thePanasonic Euro-7 chassisBrian Storm begins an account of the circuitry andfeatures incorporated in what must be one of themost complex TV chassis ever introduced in theUK. Part 1 looks at the power supplies, themicrocontroller system, circuit protection and thesignals processing arrangements.

718 PIC-based TV patterngenerator

Denis Mott's portable pattern generator design isbased on a PIC microcontroller chip. It's easy touse, producing a range of patterns for TV setassessment. A modulator is included to provide anoutput at UHF. The unit can be powered by fourAA batteries or a 240V AC mains supply.

729 Help wanted730 Thomson's ICC17 technologyIn this concluding instalment Mark Paul describesthe circuitry used in the microcontroller, signalsswitching and audio sections of the chassis.

734 LettersDTT channel revisions. Faulty scan coils. Fuseproblem. Pioneer laser lenses. Corrections.

TELEVISION October 2002

738 DX and satellite receptionTerrestrial DX and satellite TV reception reports.News on international TV broadcasting andsatellite band changes. An unusual interferenceproblem. More on moon -bounce reception. A low-cost satellite spectrum monitor. Roger Bunneyreports.

741 Test Case 478

742 Satellite notebookLNB local -oscillator setting. Digital channelupdate. C -band reception. Some digibox faults.

744 MonitorsGuidance on repairing monitors and relatedequipment.

746 VCR Clinic

748 Audio faultsHints and tips on repairing professional andconsumer equipment.

750 TV fault finding754 Web serviceUseful websites for TV professionals, techniciansand enthusiasts.

756 Jack's workshopHoliday problems with a mobile phone, a PC faultand some digibox faults, in particular those causedby CPU overheating.

758 DVD faults

759 Bench notesAdrian Gardiner provides servicing notes on theBeko C14 chassis and cheap Daewoo VCRs.

760 What a life!A voice from the past, but things have changed!Various TV faults and a dud CD player. DonBullock's servicing commentary.

762 Next month in Television

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The software bug problemWby do we have to put up with the hugefrustrations caused by computer

systems that don't work properly? Every sooften problems with a computer system for apublic utility, government department, thehealth service or whatever hit the headlines,one suspects because they provide anopportunity to score political points. Thelatter doesn't help one bit. The problem ismuch more fundamental. According to arecent study by the US CommerceDepartment's National Institute of Standardsand Technology (NIST), major softwareproblems cost US companies some $60bn in2001. But this is only part of the sorrysituation. Most problems with computersoftware are suffered by smaller companiesand individual users who don't have access toan in-house IT department that can try, withvarying degrees of success, to sort things out.It has been estimated that in the US the realcost of software difficulties is three-fourtimes the NIST figure. Basically, the cause ofthe problem is poor quality computer code.Why does this occur?

We usually want our PCs etc. to be able toperform relatively straightforward taskswithout doing a funny or producing a weirdo.And we want a good degree of compatibilitybetween older and newer programs andprograms from different sources. There hasbeen criticism of Microsoft over the yearsbecause of its dominant position and the wayin which it has achieved this. But itsdominance has probably helped enormously.One dreads to think of the horrors that couldhave arisen from scores of softwarecompanies all trying to do somethingdifferent and/or 'better' to try to gaincustomers. What's really needed is industrystandards: short of that, Microsoft serves thepurpose, though not without many a glitch,snag or bug, call it what you will.

Efforts at 'bettering' computer systemsand programs are the cause of many of ourproblems. We're told we need this latestversion of something or other. The cynicalamongst us would suggest, often rightly, thatthis is because the previous version wasdefective. How often have you had somethingnew installed, often as an unrequested`upgrade', only to find that things don't workas well as they did before? It has happenedoften enough in our editorial office. "Oh, wedidn't know you did/wanted that" comes thereply from the interfering IT person. No, youdidn't, and it's unlikely that you will be ableto come up with a solution, maybe becausethere isn't one.

The electronics industry has providedremarkably reliable computer hardware overthe years, with a high degree of compatibility- basic motherboards, power supplies, drivesand so on. In comparison, the computersoftware industry seems to be a shambles.Operating systems have often beenintroduced without thorough testing. They are

tried out, work, go on sale then someone asksthe system to do something quite reasonableand it collapses. The requirement hadn't beenenvisaged. "We didn't think you did/wantedthat" again. And so back to the drawingboard, or whatever computer programmersuse (more computers unfortunately). Sometime later another version appears. It oftencreates its own problems.

Is one asking the impossible of softwarefirms? Maybe. But if straightforward systemsthat have been thoroughly tested, without anypressure from the sales side to releasesomething 'new', had been the order of theday we would have been far, far better off.Those dozens of versions of programs justseem to cause incompatibility problems.

Many of the problems stem from the toolsand languages used by programmers. Therehave been improvements, but manyprogrammers continue to use old computerlanguages such as C and Cobol. A furtherproblem is that the software industry valuesnew code writing more highly than the testingand debugging of products and effectiveintegration of programs. The causes of thiscan be traced back to university computercourses that concentrate on program writing.What's far more important in practice isbeing able to get programs from differentsources to work together and provide reliableresults. It seems that students don't appreciatethis, maybe because of the guidance they aregiven. They regard testing and debugging asthe uncreative aspects of softwaredevelopment.

According to NIST, computer sciencegraduates are often not trained in writing

basic specifications and testing. Mostspecifications for computer programs arewritten in English, which is inherentlyambiguous. NIST is working on a formallanguage, quasi -mathematical, that it hopeswill produce more reliable products.

But heaven help the man from the ITdepartment, who is expected to be able tosolve the problems caused by the training andattitudes in the software industry. We, theusers of computer software, deserve better.

Unfortunately it seems inevitable that ourfrustrations will continue, despite the fact thatthe industry has had more than enough timeto get it right: commercial computing hasbeen with us for over half a century, and theIBM PC system has been in use for roughlyhalf that time.

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TELEVISION October 2002 70-

TELETOPICSBlue -laser disc formats

Toshiba and NEC have jointly proposed tothe DVD Forum a next -generation, high -capacity blue -laser disc format that wouldenable manufacturers to continue to useexisting DVD plant and equipment. Theproposed format covers both read-onlydiscs, used to distribute high -definitionfilms etc., and read -and -write discs. It usesa 405nm wavelength laser and the samedisc technology that's used for currentDVDs - back-to-back bonding of two0.6nmi thick 12cm diameter discs. Themain difference from a previouslyannounced proposal, Blue -ray (seeTeletopics April 2002), seems to be in theform of the disc. The Blue -ray discs wouldbe supplied in a protective caddy and havea somewhat higher storage capacity.

The Toshiba/NEC-format discs have a

Freeview DTTThe BBC and Crown Castle have announcedthat their free -to -view DTI' service,successor to ITV Digital, is to be known asFreeview. In addition to the changedmodulation standard mentioned last month,power -doubling trials are to be carried out atall transmitter sites and channel equalisationconsidered where possible. The change from64QAM to 16QAM will reduce the effect ofimpulsive interference while the overallmeasures will increase coverage and improveservice reliability.

The channel line-up is expected to be asfollows.Entertainment: BBC 1, BBC2, BBCChoice, ITV1, ITV2, Channel 4, Channel 5,S4C, Sky Travel.

storage capacity of 15GB for the single -sided, single -layer read-only type, and20GB for the single -sided, single -layerrewritable type which uses land andgroove recording. These capacities aredoubled for dual -layer versions. The basicincrease in capacity compared with currentDVD discs is made possible by the use ofa blue laser with new signal -processingand phase -change recording technology.

In February the DVD Forumestablished two sub -groups to studydifferent approaches to the next -generationblue -laser format. One is considering anapproach based on an 0.6mm discsubstrate (the same as with current DVDs),the other an 0.1mm cover layer asproposed by Blu-ray. Toshiba and NECseparately promoted research on an 0.6mm

News and sports news: BBC News 24, SkyNews, Sky Sports News, CNN, ITN.Culture, history and ideas: BBC4, UKhistory.Movies: Turner Classic Movies.Children's services: CBBC, Cbeebies,Boomerang.Citizenship: BBC Parliament (previouslyavailable via DTT as audio only), TheCommunity Channel, S4C2.Others: QVC, TV Travelshop.Interactive: BBCi (interactive TV and text).Radio: Six BBC Radio services.Two general entertainment channels and amusic channel are to be added, also otherinteractive services and commercial radioservices.

The Dixon Tele-Lift is the answer to yourTV lifting problems, eliminating all stress tothe back and any other part of the body.Designed by technicians, this strong, light-weight lifting aid can be used with all cur-rent TV sets, lifting up to 100kg safely bymeans of suction pads. It's stable overrough ground and on stairs, has continu-ously variable height adjustment and canbe used as a workbench for field servicing.The Tele-Lift is manufactured in Australiaand is to be launched in the UK shortly.Meanwhile it can be obtained via the inter -net. Sony Australia has officially approvedthe Tele-Lift for use in the company's ser-vicing and distribution operations. Thewebsite address iswww.liftingsystems.com.auor you can [email protected]

disc substrate and, after verifying oneanother's technology, decided to propose aunified format. The companies say thattheir format provides a cost-effectiveupgrade path for media vendors, withbackwards -compatibility for consumerswho have built up DVD libraries. Otheradvantages are absence of the need for acaddy, which enables slim drives that canbe integrated into portable equipment to bebuilt, and the fact that dual -layer discs areeasy to create, as the back-to-back bondingof 0.6mm thick discs is the same as withcurrent DVDs. The data transfer rate is36Mbits/sec (same as Blue -ray) while thenumerical aperture of the objective lens is0.65.The new format would also meet theneeds of the PC industry optical -drivebusiness.

Beko-Grundig link?There have been unconfirmed reports of apossible link between Turkish TV andappliance manufacturer Beko and theGerman consumer electronics groupGrundig, which has been going through adifficult period. Grundig requiresadditional finance and would welcome anequity interest being taken by an outsideinvestor. For Beko the advantage would beuse of the renowned Grundig.

ITV Digital: the endThe final stages in winding up ITV Digitalare being undertaken by the administratorDeloitte & Touche. Various assets,including some 100 of those knittedmonkeys, were auctioned in earlySeptember. The monkeys were left overafter 32,000 were sold to two customers,one of which was The Gadget Shop. Thefinal stage will be to place the company inliquidation, but consultation with thecreditors' committee is required beforethis can be done. It's understood that theadministrator has been negotiating withtwo interested parties about the 750,000 orso set -top boxes in former subscribers'homes. All proceeds will go to theliquidators for distribution to the creditors,which include Carlton, Granada, Sky TV,the Football League and Crown

Camera -phonesAccording to a report from StrategyAnalytics, mobile phones that incorporatea camera will soon be outselling digitalstill cameras. The researchers predict thatby 2007 sales of camera -phones will havereached 147 million a year.

708 October 2002 TELEVISION

The green tax effectManufacturers and retailers of domesticelectrical and electronic products areconsidering how to pass on toconsumers the new environmental coststhat are to be imposed on them. Theprices of refrigerators, TV sets and PCsin particular will rise as a result of theEuropean Union directive (WEEE) thatmakes manufacturers/distributorsresponsible for recycling products at theend of their useful lives.

Manufacturers, including Panasonic,Electrolux and Sony, feel that costincreases should be made clear toconsumers. They want to impose a`green fee' of £10 or more per item atthe point of sale, in addition to the pricerise required to cover the cost of

recycling the item being sold. The greenfee would pay for recycling productsmade by companies that no longer existand equipment made ten -twenty yearsago. Retailers oppose such a scheme,saying that it would impose extra costson them and make them, in effect, taxcollectors.

Fred Round, chief executive ofRETRA, insists that a visible fee wouldmean hassle for shopkeepers - morebook-keeping and implications for pricetracking.

The EU is still discussing howexactly manufacturers and distributorsare to be made to pay for the disposal ofequipment, and whether this decisioncould be left to individual countries.

Technology developmentsFollowing work by the National PhysicalLaboratory and the Institute ofNanotechnolgy at the University ofStirling, the UK Advisory Group onNanotechnology Applications hasrecommended to the government that two£25m a year nanotechnology fabricationcentres should be set up. The aim wouldbe to try to keep abreast of worldwidedevelopments in this field (see article inthe August issue). It's understood thatsome $710m will be spent onnanotechnology development in the USnext year, while there are plans to spendsome $650m in Japan.

Fujitsu Laboratories in Tokyo hasdeveloped a way of growing bunches ofcontrolled -diameter, multi -wall carbonnanotubes vertically on a silicon substrateto provide MOSFET connections. Carbonnanotubes are usually produced usinglaser vaporisation and arc dischargewhich, according to Fujitsu, do notprovide good control over the location,orientation and diameter of the nanotubes.Instead, the company is using plasma -enhanced chemical vapour deposition: amethane -hydrogen mix is decomposed inan electric field to produce growthaligned with the field. Diameter control isachieved by varying the amount of nickel

or cobalt catalyst in the silicide (silicon -metal) layer on which the tubes aregrown.

Intel has announced advances in itschip technology. From next year chipswill be produced with 90nm features,special material that allows insulatinglayers just five atoms thick to be created,and microscopic copper instead ofaluminium wiring to provide fasteroperation. In addition the chips will use`strained silicon'. This increases thedistance between the atoms by one percent, significantly increasing electronflow and chip performance.

Video productsThomson has launched a combined DVDplayer and Nicam VCR, ModelDTH6000U, which is expected to retail atabout £300. Features include MP3playback, two scart sockets, RF loop -through for easy installation with otherAV equipment, front AV connectors foreasy recording from external equipmentsuch as a camcorder, and the NextViewlink system which provides easierinstallation and programming whenconnected to a Thomson TV set.

Panasonic has launched a DVD-AudioNideo player, Model DVD-RA82,

Cover photo: The Sony TV projector unitfeatured on this month's cover can bepositioned to the side of the screen yetstill produces a symmetrical picture as itincorporates both horizontal and verticaldigital keystone correction.

which is also compatible with DVD-RAM discs and includes a DolbyDigital/DTS decoder, a Super Hi -Speedscan facility that gives 200 times normalplayback, a quick replay button thatjumps back 7-10 seconds on a disc, and a4:3 TV zoom control that's designed toeliminate black bars with widescreendiscs. Price is expected to be about £250.

Philips has launched ModelDVD763SA, which can handle DVD,SACD, CD, CD-RW, CD -R, VCD and S-VCD discs. It will also play back MP3sound recorded on to a CD via a PC.There are built-in decoders for DolbyDigital and DTS recordings. In additioncoaxial and optical digital outputs providePCM, MPEG, Dolby Digital and DTCsignals for external decoding. Price isexpected to be around £250.

DAB radio at £99VideoLogic Systems has released the firstdigital radio broadcasting receiver, thePure Evoke -1, to sell at the low price of£99. A limited edition to test the marketwas made available last year, and high -volume production has now started. Ituses third -generation DAB technologyand is being well promoted. This couldwell be a breakthrough for DAB.

Thomson Multimedia has developed this solution for thosewho want sound in a different room or outdoors without

the hassle of having to use extension leads - wireless loud-speakers. Sound is transmitted to the stereo speakers at

863MHz. The transmissions pass through walls and areusable at up to 80m. The two speakers, type WSP740, can

each deliver 3W RMS and have a volume and bass boostcontrol. They also have a built-in charging circuit for

rechargeable batteries, and magnetic shielding to preventinterference when used near PC monitors or TV sets. For

further information contact Thomson Multimedia on 01732520 920 or go to the website at

www. thomson-europe.com

TELEVISION October 2002 709

Memory technology developmentscore's Law was first pronouncedby Dr Gordon Moore, co-founderof Intel, in 1964. It states that the

quantity of information that can be stored ina given amount of silicon will roughlydouble each year. The prediction held trueuntil the late Seventies, when the doublingtime slowed to every eighteen months. It hasstayed there ever since. But physicists saythat with current integrated -circuittechnology the Law will cease to apply sometime during the decade 2010-2020, when thegates that control the passage of informationwithin a chip become as small as thewavelength of an electron - approximatelyten nanometres in silicon. At this pointtransistors cease to work.

Of the more than 100 quadrilliontransistors that Gordon Moore estimateshave been produced to date, nearly all havebeen formed directly on the surface ofsilicon crystals, in two-dimensionalconfigurations. So far IC designers havebeen able to prove Moore's Law byshrinking the size of each transistor,doubling their density per microchip.Expanding the chip area has also helped.But, with increasing technical difficulties,progress along these lines has started tolevel off. This has prompted a review ofchip design and a move towards three-dimensional (3D), i.e. vertical, fabrication.

The electronics industrymay be in recession, butresearch anddevelopment continue.Ralf Buckstone reports ondevelopments in thememory field

It could restore the validity of Moore'sprediction - and give us greater computingpower at less cost.

It would be misleading to suggest thattoday's chips use 2D design exclusively:Intel's Pentium 4 microprocessor forexample boasts seven levels of 'wiring'embedded in insulating layers.Nevertheless, only the bottom layer ofsilicon contains the active semiconductordevices.

Physical limitationsMoore's Law has continued to be relevantbecause the IC industry has been able toimprove the way in which that bottom layerof silicon is used. Very large siliconcrystals, 30cm in diameter with less thanone part per billion of impurities, can be

3-0 vs. COWSNTiONALmiCHNOLOGrir

Insulator

Metal

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StandardCMOS

Moon

Commercialmicroprocessor

Interconnect

Sillsub

grown. There have been improvements inthe deposition of carefully -controlled dosesof doping material into the wafers cut fromthe crystals, and in the resolution of thephotolithographic processes used to definethe treated regions to form transistors andtheir interconnections.

But photolithography is subject tolimitations dictated by the laws of physics -to continue to pack more transistors on to awafer calls for light of ever -shorterwavelength. Mercury -vapour lamps havebeen replaced by deep -ultraviolet lasers thatcan define 130 nanometre features, puttinga billion transistors on a chip. Furtherimprovements could push the limit to65nm, creating perhaps 16 billiontransistors. Beyond this, the road gets a bitbumpy and less secure with regard to thereturn on effort and investment.

The 3D approachWith the limitations of 2D fabrication beingapproached, one might ask why silicon ICdevelopers haven't moved to verticalfabrication? The answer seems to be speedand reliability, both of which are optimisedwhen an IC is formed of perfectly -alignedatoms in a wafer cut from a single siliconcrystal. Once a semiconductor wafer hasbeen coated with an insulating oxide layer,and metal conductive paths have beendeposited, there's no known way ofreaching the underlying crystalline pattern:it has been described as like trying tomatch the pattern of a parquet floor aftercovering it with a carpet! And silicondeposited on to a non -crystalline(polysilicon) surface tends to becompletely disordered (amorphous).

The idea of 3D (vertical) chip fabricationhas been around in Silicon Valley for yearswithout any commercial success beingachieved. Several universities conducted3D chip experiments in the Eighties, butthese failed because exotic materials orunusual designs were required. As a resultthe traditional approach to chip fabricationhas continued and engineers stopped givingmuch thought to 3D possibilities - until twotechnical developments encouraged areassessment of 3D IC design.

BreakthroughsThe first breakthrough came from the flat -panel display industry, with thedevelopment of technology that depositsmillions of transistors as a thin film spreadover a large, amorphous glass substrate.


II II II IIII 11_11 III

1111111111_11.110

This vertical stack of memory cells canstore eight bits in the area normally usedfor one bit.

The second development, called chemical -mechanical polishing (CMP), was devisedin IBM's research laboratories in the lateEighties. This technique smooths eachsubstrate layer sufficiently to enablesubsequent layers to be addressedphotolithographically while retainingcorrect focus.

3D circuits have been made possible bycoating standard silicon wafers with manysuccessive layers of polysilicon, as well asinsulating and metallic layers, with thesurface polished flat after each step.Although electrons do not move as readilyin polysilicon as in single -crystal silicon,3D transistors with 90-95 per cent of theelectron mobility achieved withconventional 2D fabrication have beenproduced.

A firstMany companies have attempted todevelop 3D circuits in the past. MatrixSemiconductor claims to be the first tohave devised practical methods ofproducing them in high volume. The firmalso claims to be able to create morecircuit layers than anyone else, by using anintricate web of vertical electricalconnections and layers of microscopicfilms. This approach enables the ICfootprint to be shrunk, so that far more ICscan be obtained from a wafer, cutting costsdramatically. The first product is expectedto have eight layers and to be available onthe market later this year. ICs with twelveand sixteen layers are planned.

Although vertical stacking is used,standard CMOS fabrication, semiconductor'material and production equipment areemployed. By stacking memory elementsvertically, Matrix Semiconductor claims touser a smaller wafer area for a given devicedensity than traditional DRAM, SRAM,flash and mask -ROM designs, improvingthe yield. According to the company,"vertical electronics can reducemanufacturing costs ten -fold or more, andthe density of 3D devices should increase atleast as fast as Moore's Law states as layersare added".

ProblemsCurrent 'high-rise' 3D technologies arenot without problems. The proportion ofdefects in the chips means that 'fault -

Cross -section of the first truly 3D ICproduced by Matrix Semiconductor Inc.

tolerant' techniques are required to workround the anticipated flaws. The chips arealso slower in operation than conventionallow rise' ICs, and heat dissipation is a

greater problem as so many moretransistors are crowded into the samepackage. The history of technologicaldevelopment suggests however that whenthere's a strong economic incentive asolution will be found.

The way aheadFor thirty years chip manufacturers havebeen printing ever -smaller transistorstructures within a single plane. It seemsinevitable that in future microcircuits willbe scaled vertically as well as horizontally:the technology is possible and practical,and the benefits compelling. Yet the 2Dapproach is far from reaching the end ofthe road. IC designers continue to be ableto shrink transistors and beef upperformance using the more conventionalapproach. As an example of the continuingprogress, Intel and Advance Micro Deviceshave announced a reduction in the size oftheir flash memory chips this quarter,lowering the cost while increasing memorycapacity and volume.

First consumer applicationThe '8 -story high' 3D memory chip willhold 512 million memory cells of thewrite -once type at a cost comparable tomagnetic or optical storage. The memoryhas enough capacity to be able to store anhour of high -quality audio (with datacompression) or a few hundredphotographs. It is seen as a viablealternative to disc, 35mm film and audiotape. Thomson Multimedia has shownserious interest and has agreed to use thechips. David Geise, ThomsonMultimedia's vice-president of accessoriesproducts, has announced that the companywill, later this year, "incorporate Matrix's3D Memory in memory cards that can beused to store digital photos or music". Thecards plug into cameras, and Thomson isworking on a reader that will enable usersto view digital photos via TV.

Cost is apparently what makes theThomson/Matrix card different fromcompeting flash cards from Sony andToshiba. Because of Matrix's chip design,a 64MB Thomson card will cost about as

The polysilicon layers that form the honey-comb of memory cells shown left are inter-connected by the vertical columns at theright. These are in turn connected by tung-sten wires (shown as bright structures).

much as camera film does at present -close to $10 according to Matrix estimates.To strengthen the association with film, thecards will be sold under the nameTechnical Digital Memory Card. Versionspromised later will have storage capacitiesof 128MB and 192MB. TaiwanSemiconductor Manufacturing Co. isproducing the chips for Matrix.

The NRAMA totally different approach to increasedmemory density is presented by carbonnanotube technology (see page 650,September issue, for an explanation ofnanotubes). A race is on to develop acarbon nanotube-based non-volatileread/write memory that will provide at leastten times denser storage than day's typicalmemory chip. The approach has been called"nanoelectromechanical", or NRAM. Theway in which these devices seem to work isamazingly like the mechanical -relaymemory, such as the relay -driven binaryadder used in about 1940.

Greg Schmergel, CEO of Nantero,explains this as follows. "NRAM will usean electromechanical approach to memorystorage rather than using electrical charges.The building blocks are carbon nanotubes,the smallest of which are so thin that atomsmust pass through in single file. Byaltering charges, the tubes can be made tobind together or separate, creating the onesand zeros that form the basis of computermemory. The tubes stay in the same stateuntil a change is made, so the memory isnon-volatile."

In current memory design electricalcharges are switched on or off to representones and zeros. Nantero's co-founder andChief Scientific Officer Thomas Rueckesfigured out that nanotubes could be madeto move up and down to represent.the onand off states. Because of the small size ofnanotubes, a memory the size of a fingertipcould store many gigabytes of information.

Nantero believes that its NRAM has thepotential to "replace all existing forms ofmemory - such as DRAM, SRAM andflash - with its high -density, NV NRAM".Its first goal is to create a 1GB commercialprototype, and there are hopes of a 1TB(Terabyte) chip within three -five years.


A serviceman's guide to thePanasonic Euro-7 chassisBrian Storm begins an accountof the circuitry and featuresincorporated in one of the mostcomplex TV chassis everintroduced in the UK. Part 1looks at the power supplies, themicrocontroller system, circuitprotection and the signalprocessing arrangements

Mains bridgerectifier

L810

L893

L894

AC inputto board D

De-gaussing circuitvia RL802

R841562W

ArD842

C84710

450V

4n7

D843

14

R842100k1W

D844

D845

The Pansonic Euro-7 chassis wasintroduced in late 2000 for usein high-performance, large -

screen TV sets, replacing andupdating the by then ageing Euro-5chassis. It has a number of featuresthat were new to the Panasonicrange, including progressive -scantechnology, twin RGB inputs andtwin UHF tuners.

The main features of the chassis areas follows: 3D on -screen graphicaldisplays, owner ID storage forsecurity, progressive -scan mode,advanced 100Hz processing, twotuners for PIP and PAP, picture andteletext (PAT), a 1,000 -page teletextmemory, a sub -page teletext

memory, onboard operating softwarestored in an upgradeable flashmemory, coaxial and optical digitalaudio inputs, AC3 and DTS audioprocessing, 5.1 -channel onboarddecoder and output stages, S2widescreen switching with AV3S, 3 -to -2 field pull -down recognition forNTSC films, and dynamic auto -focusing.

The owner ID system is identical tothat in the Panasonic Euro-4 andEuro-5 chassis. It enables owners tostore their name and postcode in aset's user memory, protected by afour -digit PIN code. If the policeshould be involved in a recovery, asticker on the back of the set advises

Fig. 1: The standby power supply circuit used in thePanasonic Euro-7 chassis. IC841 is type MIP0254SPSCF.

1C8443n91kV

A D847

2

T841

5

3 1C841

I

100

C843 eft 100p0.1

D848

D888

01

r= C8882,20016V

Stby 5V

R881 R8841k2 1k

o C883

TiO

50V

C8854735V

D886

D885


them to press and hold the F buttonin the front flap for five seconds.The owner's details will thenappear on -screen.

Standby power supplyThe Euro-7 chassis has no standbymains transformer. Quite simply,half -wave rectified mains voltage isfed to pin 5 of a small eight -pinchip, IC841, see Fig. 1. The 560safety resistor R841 in series withthe feed will go open -circuit in theevent drastic failure within IC841.The slow -start capacitor C843,connected to pin 1, enables the setto resist the initial surge with a coldstart. T841, the small standbychopper transformer, providesmains isolation in this area.

D888 and C888 on the secondaryside of the circuit produce a 5Vsupply for all the circuitry inoperation during standby, i.e. themain microconctroller chip IC1101,a flash ROM and an EEPROM.Additional circuitry providesregulation for the extra powerdemand when the set switches on.

D802

Aains ACrom L810

T

4n7

4n7

R8012.77W

=C820

400V

Optocopler D848 senses variationsin the output voltage, with D886and D885 providing a constantreference voltage. Feedback is topin 4 of IC841.

Many of the circuit diagrams I'veseen have a link missing betweenD843 and pins 2 and 3 of IC841.Draw in a line and the circuit makessense! Also ignore the twocomponents usually shown in serieswith C847. Wire links are fitted inthese positions. The components arelabelled JW on Panasonic circuits,JW standing for jumper wire. Thisis not uncommon with Panasoniccircuit diagrams.

DegaussingThis chassis is designed to providedegaussing when the standby modeis left, hence relay RL802 which isconnected to the degaussing circuit.This recognises that today's userstend to leave their sets in standby.Thus degaussing never takes placewhen this is designed to occur atmains switch on, the risk being adiscoloured raster. The Euro-7

Ferrite bead

chassis degausses every time itcomes out of standby.

Main power supplyThe main chopper power supply,see Fig. 2, is a development of thearrangement used in the Euro-4chassis, with the addition of theMOSFET power transistor Q805 inwhat could be described as anactive -snubber arrangement. It helpsto cater for the extra current demandwith the Euro-7 chassis.

IC801 is a self-contained chopperpower supply which is started byapplying 15V to pin 4 via R803 andR804. Once the circuit starts up,D819 takes over provision of thesupply for IC801. This supply ismonitored by IC80 lintemally:should it rise dramatically, aninternal latch is activated, switchingIC801 off. This latch is alsoactivated if IC801's bodytemperature exceeds 140°C. Torestart the power supply, the mainsinput must be switched off thenreapplied.

The voltage across R806 and R810

_LNon-isolated chassis min Isolated chassis

IC82312n400V

11

C819

R803470p

mm

18k500V

II

II

II

3WR80418k3W

AMD805

C80822035V

3

IC801

STR-F6656LF53

D809

R819680

D811

R806 R8100.12 0.12

on C817680p2kV

D820

5k6

T801

2

D819 8

14 0

1k5 D821

680p

R8371k5

18

R868 D856

1n

-IID855

C868680

160V

D823

560p

D851

Fig. 2: The main power supply circuit used in the Euro-7 chassis.

1k8

15k

2

D852 T

0 C862 0 C86922, 250v0 42, 750v0

Trrt

IC851SE140N

20V

Audiocircuitsupplies

20V

144V

EW circuit

14V


CVBS10' Shoal

CVBS2

16..21

Slicer2ACO

Addr.

t6

Data

Fig. 3: Internalarrangement of

the SDA6000microcontrollerchip used in the

Euro-7 chassisfor system con-

trol and teletextprocessing.

External

BusInterface

16

SRU

FIFO

3 x6BuDAC

D -Cache

1 -Cache

Boot

ROM

16

32 InstoData

16

CPU -Core

C166

X -BUS itrstr .0ara

XRAM2 Kbyte

Imerrupt Controler

PEC

36 nodes (6 ext

16

16

InternalRAM

2 Kbyte

OSC(6 MHz)

DS.inc

VH V

GPT14- GPT2

12T5Channel

ADCUSART

ASC

SPI

SSCI :"C RTC Watchdog

137-tt 16

T4

Port 5 Port 3 Pat 2 Port 4 Pcrt 6

/6

is monitored at pin 1 of IC801 todetect excess current conditions.Should the current drawn by thechopper MOSFET in IC801 beexcessive, the power supply willpump until the overload is removed.The free -running frequency of IC801is set by C829 and R837.

IC851 on the secondary side of thecircuit acts as a 140V constant -voltage regulator, with help from the3V zener diode D852. Pin 2 of IC851produces a variable current outputdepending on the voltage at pin 1.This drives the optocoupler D823,providing regulation feedback to pin1 of IC801 on the primary side of thecircuit. In this way any fluctuations inthe HT feed to the line output stageare ironed out.

The main microcontrollerAn SDA6000 Infineon C166microcontroller chip with an M2 core,IC1101, is used for system control inthe Euro-7 chassis. It also generateshigh -resolution graphics and provideshigh-level teletext processing. Fig. 3shows the internal arrangementswithin the chip. Use of this advancedprocessor makes it possible to userewriteable flash memory for theonboard operating software.

IC1101 lives on board U, whichplugs directly into the main signals

/is /8 /8.C7

PCB (board A). Because it is possibleto plug this sub -panel into board Atwo ways, large arrows are printed onit. These point directly to the nearestedge of board A. Connecting board Uwrongly will not cause any damagehowever.

Board U also houses an 8Mbyteflash ROM chip, IC1102, and a16Mbyte text memory, IC1106. Fortest purposes board U can be swappedwith one from another set, as themodel specific data is stored in astandard eight -pin EEPROM,IC1104, on board A.

At least half of IC1101's 128 pinsare used for reading from and writingto IC1102 and IC1106. Importantpins for fault-finding are as follows:pin 73 is the master reset input fromIC1254; pin 106 is the 3.3V supply tothe main operational section; pin 107is the main chassis connection; pins108 and 109 are connected to the6MHz crystal X3501; pin 115 is thechassis connection for the 2.5Vsupply; pin 123 is for the 2.5Vsupply.

From this it's clear that IC1101 hastwo supplies, 3.3V which is used bymost of the IC and 2.5V which isused by the sections associated withpins 110-128. Keep this in mind,because if the 2.5V supply is missingthe 3.3V supply is switched off by

3

OLDS

4-XTAL

JTAG

Q1121 and Q1122 on board A.Other important pins are as follows.

Pin 5: Remote control data input.Pin 76: Enables the serial connectionto AV1 for memory packs in theservice mode.Pin 82: Activates the degaussingcircuitry.Pin 92: Activates the mains inputrelay RL801.Pin 93: Monitors for digital errorsand mutes the sound to preventspeaker damage.Pin 94: Monitors the 5V supply. Ifthis fails momentarily, IC1101 has toreload all the digital processor chipswith operational data and reset them.Pins 74, 75, 98, 99,100 and 101:These are the serial data connectionsfor control of and data loading to allthe digital processor chips.Pins 102 and 103: These are the100Hz synchronisation inputs fromboard DG.Pin 104: Contrast reduction output tothe RGB processor chip IC1315.Reduction is activated when on-screen menus are displayed to preventdoming and discoloration in high -brightness areas.Pin 105: Blanking feed to the RGBprocessor chip IC1315 for teletextand on -screen displays.Pins 112-4: RGB outputs to the RGB


processor chip IC1315 for teletextand on -screen displays.Pins 120 and 121: Composite videoinputs, used for stripping off teletextinformation and synchronisation ofthe user menus.Pin 124: The keypad feed. As withall modern Panasonic TV chassis,this uses the voltage -sensingprinciple, not a key matrix. Aresistive ladder is wired across thelocal key inputs. Whichever key ispressed determines the voltage atpin 124 of IC1101 and therefore thefunction.Pin 127: This is the generalprotection pin for the whole set. Thevoltage here is normally high, at2.5V. It's pulled low to provideprotection, the set going to standbywithin five seconds.

Protection circuitryHaving got to pin 127 of IC1101,we must take a look at the circuitrythat initiates protection. It monitorsno fewer than eight parameters, seeFig. 4. Pin 127 of IC1011 isconnected via R1154 to D867, D869and the collector of Q854, which areall on board D. D867 is connectedto the 14V supply and D869 to thefield output stage's +15V supply. Ifthere is a short-circuit across eitherof these supplies pin 127 will betaken low. It will also be taken lowwhen Q854 conducts. The base ofthis transistor is connected to six

HINM'JINN

SYNCENM

CLKIV

YlNla

UVINM

YINS

WINS

CLKS

HINS

VINSSYNCENS

monitoring circuits.D865 is connected to the -I5V

supply to the field output stage. Inthe absence of this supply D865conducts and Q854 switches on.Two conditions in the line outputstage are monitored, on the primaryand secondary sides. On the primaryside line flyback pulses from thejunction of C554/5 are fed to thecathode of the 36V zener diodeD595. Excessive pulse amplitudewill switch on D595, D594 andQ854. On the secondary side of theline output stage D591 and the10.4V zener diode D592 monitorthe flyback pulses in the CRT'sheater supply. D593 rectifies thepulses, charging C591. If the CRTheaters go open -circuit or theamplitude of the pulses is excessiveD592, D591 and Q854 conduct.

The HT supply to the line output

IC1101

2.5V

D867014V

R1153 D86956k e I 015V

R1154

7

TEST RESET

1k0854

2SC3311A3k3

150k

stage is monitored by Q851, whichchecks the voltage across resistorR857. If this voltage is excessive(excessive current demand), Q851.D859 and Q854 conduct.

MN

HT144V

D859

R857 2.2 7W

D865

HD594

14

10 50V

08512SA10180

33k

820

0-15V

D595

Fig 4: Themonitoringcircuitry thatinitiatesprotection.

Line outputstage

33k

330kAAA,

Line flyback pulsesfrom C554/5

D591 D592 11k3 D593 10Pulses from CRTheater circuit

doC5919k31 T 10

rn`n 50V

D861 D862

D454

14

R8565k6

12V

C451

X2 Iii XlICLKD

1k From EW drive circuit,'\,\Ar junction of R719/L702

D452 100 From fieldscan circuit

ISCMInput sync controKer Master

clockdoubling

PLLM

---rIFCMInput

format-01, conversion

LMLine memo

VHCOMMVertical andhorizontal

compression/expansion

LBDLetterbox

detection

TSNRTemporal,

spatialnoise

reduction

IFCSInput

formatIlikconversion

jiclockdoubling

PLLS

VHCOMSVertical andhorizontal

compression/expansion

LMLine memory

4 ISCSInput sync controller Slave

EDeDRAM

Buffer

Voltagecontrol

Test -controller

VMVector

memory

MEmotion

estimation

-41LM

Linememory

gr MCi Memory 4

It Controller

SRCMScan rate

conversionMaster

Verticalexpansion

SRCS

clockdoubling

PLLD

OSC M/SOutput synccontroller

Master

gCLKOUT

INTERLACED

11011 HOOT

PS VOUT

9 BLANK

MU -go

DLTIDCT1

Peaking

OFC4:4:4

.411 8:8:8Framing

Delay

I'C

YO

UO

9 VO

YOUT

INOUT

Fig. 5: Block diagram of the SDA9415 IC.


The EW circuit is monitored viaD861 and D862. This circuit checksthe flyback pulses coming backthrough the EW loading coil. If thecoil starts to fail, protection will beinitiated before damage occurs inthe EW drive circuit.

The final monitoring circuit is onboard A, for the field output stage.The main items here are D454,Q451, C451 and D452. In normaloperation D452 rectifies the fieldscan, charging C451. Q451 is heldconductive and D454 is biased off.In the event of field scan failureQ451 switches off and D454 isforward biased by the 12V supply.Thus Q854 again conducts.

No one should approach fault-finding in this protection circuitryby simply isolating pin 127 ofIC1101 from the monitoringcircuits and looking for smoke.Simple voltage checks will showwhich circuit is activatingprotection and thus where to lookfor the fault.

PCB APCB A contains all the signalprocessing circuitry and the fieldand audio output stages. It followsPanasonic practice apart from theprovision of two UHF tuners, themain tuner TNR003 and the sub -tuner TNR004. The main differenceis that there is no sound output fromthe sub -tuner, which is used toprovide picture -in -picture andpicture -and -picture displays.

Board DG plugs directly intoboard A. It provides 100Hz up -conversion or progressive scanningand all the drives for the field andline output stages etc.

The surround sound stages are onboard Z and the audio processingcircuitry on board DP. These boardsare mounted above board A.

The following is a list of the ICson board A and their functions.

1C1104: EEPROM for user andmodel specific data.1C1105: 5V supply monitor forpower failure.1C1107: Level -shift processor for3.3V data (PCB U) to 5V data (PCBA).1C1108: 5V regulator for the infra-red receiver circuit.1C1109: Reset generator for PCBDG.1C1251: 3.3V regulator for PCB U.1C1252: 2.5V regulator for PCB U.1C1253: Sub -processor outputexpander, controlled by IC1101.1C1254: Reset generator for PCBU.1C1315: RGB processor.1C2001: Audio processing andswitching.1C2301: Left- and right -channelaudio output stages.1C2302: Headphone amplifierstage.1C2303: Right -channel acousticfeedback processor.1C2305: Sub -woofer output stage.1C2306: Left -channel acousticfeedback processor.1C2307: Acoustic feedback gain.1C2705 and 1C2709: 3.3Vregulators, mainly for PCB DG.1C2706: 5V regulator.1C2707: 8V regulator for IC2001.1C2708: 9V regulator.1C3001: Video input switchingprocessor and widescreen switchdetector.1C3002: RGB input switching.1C3003: Video gain for picture -in -picture balance.1C451: Field output stage.1C459: Line drive buffer.1C4801: Geometric rotationpreamplifier.1C4802: Geometric rotation outputstage.10501: EW buffer.

PCB DGPCB DG carries out the picture

Mainanalogue

video R driveMainglobalcore

G drive

B driveSubanalogue

video

SDA9415

Motion -adaptive upconversion3D picture noise reduction,

PIP, PAP, etc.

Subglobalcore

Line drive

Field drive

Analogue

REW drive

CIPDAF drive

B

Fig. 6: Signal processing on board DG,overall arrangement.

CIP forburst timing,

sync etc.

enhancement processing in thischassis. The main processor is anSDA9415. Fig. 5 shows a blockdiagram for this IC, which performsthe following operations:

Motion -vector based scan -rateconversion for 100/120Hz scanning.

Motion -vector based scan -rateconversion for progressive 50/60Hzscanning.

3D spacial and temporal noisereduction.

3D motion estimation.6M onboard picture memory.1IM onboard vector memory.Separate inputs for sub and main

picture processing.Picture -in -picture processing to

1/9 size.Picture -and -picture processing for

split-screen displays.Automatic letterbox display

processing, with flexible zoommodes.

There are also two global corevideo processors (sub and main) foranalogue -to -digital conversion andmotion -compensated luminance andchrominance signal separation. Fig.6 shows the general arrangement.Global core processors are specialPanasonic multi -standard digital -video processors that provide almostperfect digital separation of theluminance and chrominance signalcomponents, using adaptive,motion -compensated digitalprocessing. The result is a veryclean chroma signal and a widebandluminance signal. These areessential for modern large -screenTV sets and plasma panels.

In addition there are twocomponent interface processors(CIPs) to provide RGB inputanalogue -to -digital conversion andfor deriving the timing signals tosynchronise the whole system in theprogressive- and 100Hz-scanmodes.

There will be some Euro-7models, such as the TX28PG45, thatdon't have picture -in -picturefacilities and therefore have no sub -picture global core processor onboard DG. Be wary of this ifswapping DG panels between sets.

With five large surface -mountedprocessor chips and a pin count ofover a thousand, Panasonic hasdesignated board DG non -repairable. Replacement is on anexchange basis only.

To followIn Part 2 next month we'll look atthe progressive and 100Hzscanning, dynamic focusing, audioprocessing, the service menus andthe self -check.


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PIC-based TVpattern generator

Denis Mott hasdesigned thisrelatively simpleportable patterngenerator that's basedon a PICmicrocontroller chip.It's easy to use,producing a range ofpatterns for TV setassessment. Amodulator is includedto provide an outputat UHF. The unit canbe powered by fourAA batteries or a240V AC mains supply

Many different TV test patterngenerators have been designedover the years, both as

commercial and build -it -yourself projects.In the early Nineties I designed a pocketpattern generator based on the FerrantiZNA234 TV sync generator chip, withabout five logic chips, a TEA2000 colourencoder and a UHF modulator. This designwas OK for the purposes for which it wasintended. But it had shortcomings, such aspoor power consumption and a limitedrange of patterns.

With this in mind, a friend suggesteddesigning a generator based on a PICmicrocontroller chip. At the time I'd notheard of a PIC, but I found some literatureand a source of an emulator andprogrammer - the John Morrison Co.,which subsequently became Leading EdgeTechnology, Malta.

The generator had to be portable, simpleto use and provide a useful range ofpatterns. Having been in the TV trade forover 35 years, some of this time in TV setproduction and quality inspection, I feltthat I had a reasonable idea as to thepatterns required without going overboard.

I also felt that as well as an RF output acomposite video signal and an audio signalshould be provided. The result is theproject described in this article.

The patternsThe unit generates five patterns, as follows.

Colour bars: EBU-standard white, yellow,cyan, green, magenta, red, blue and black.

Grey -scale: Bars start with white at theleft and go through to black at the right inequal luminance steps.

White/grey split screen: When setting thecolour balance with pre auto grey -scalereceivers, and with later ones that haveadjustable drive/cut-off levels set bysoftware, the highlights and low lightshave to be set up, preferably withoutadjusting the brightness and contrastcontrols. This adjustment is much easierwith a white and grey signal, especiallywhen a colour -balance meter is used.

Red raster with white markers: A redraster is required for checking purity.


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Fig. 2: Suitablemains -adaptor circuit

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available from AC mainsFarnell Electronic input

Components underorder codes 365-117and 412-594 respec-

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Markers were added at -3 per centunderscan, plus a vertical and horizontalwhite line at the centre. The -3 per centunderscan lines are for setting the heightand width: set these so that the lines arejust visible from top to bottom at each side.

The centre lines are for setting thevertical and horizontal centre, using theextra dots in the CRT shadowmask'shorizontal centre plane to view the line.

Crosshatch: The outermost lines are againat -3 per cent underscan. The pattern canbe used to check convergence and set thescan linearity.

Circuit descriptionFig. 1 shows the pattern -generator circuitdiagram. IC1 is the 16F84 PICmicrocontroller chip (20MHz version).There are amazingly few peripheralcomponents for such a powerful device.X1 is a 20MHz crystal, with Cl and C2

5V

CVC\1

CO

0

Fig. 3: Componentlayout on the mainand the front -panelPCBs.

providing phase change. R11 is connectedacross the 5V supply to discharge C3 whenthe microcontroller goes to sleep. If it's notfitted, IC1 may not come out of sleep whenrequired. R13/14/15 are pull -downresistors to keep the inputs from thepattern -select switches SW2-6 tied toearth. To minimise the microcontrollerinput requirements, the switches arestrobed.

The pattern output elements appear atports RAO (blue), RA1 (red) and RA2(green), with a composite sync output atport RA3. The RGB outputs are at 5V ULlevel and must be attenuated to feed thecolour encoder chip IC2. R5 -R10 providethis attenuation.

SW1 is a reset switch, to bring themicrocontroller out of its sleep mode. Itdefaults to colour bars. Thus SW1 is alsothe colour -bar select button.

IC2 is the colour encoder. A TEA2000was used in the original design. It requires

a luminance delay line and doesn't haveRGB outputs. The Sony CXA1645Psubsequently became available and, thoughlarger, doesn't require the delay line. Inthis application its RGB outputs (pins 23,22 and 21 respectively) are not used, butthey are in a laboratory version of thepattern generator. The CXA1645P waschosen as the standard encoder for bothversions. Its RGB inputs are capacitivelycoupled to pins 2, 3 and 4. The compositevideo output is at pin 20, and is terminatedat 750. R18, which is connected to pin 18,is an unusual value (161(52), but this iswhat the device specification calls for. The4.43MHz colour subcarrier is generated bythe crystal oscillator Q2/X2 and is fed topin 6 of IC2. It's a standard oscillatorcircuit with one addition: Q1 stops theoscillator when switched on by IC1, inorder to provide the monochrome patterns(grey -scale, white/grey and crosshatch).

Over the years I've tried various UHFmodulator chips. The first was the PhilipsTDA6800, which needed a separate audiosubcarrier oscillator. Then there was thePlessey SL5162, which had a simpleconfiguration and an onboard subcarrieroscillator. Both these devices are nowobsolete and difficult to obtain. Thepresent design uses the Philips TDA8722(IC3), which is even more versatile thanthe SL5162. It can be frequencysynthesised via an I2C bus system. In thepresent application this is not needed, asthe frequency stability is very good.

L I is the UHF tank coil. It's a strip -tunedinductor on the PCB, trimmed by thesurface -mounted, subminiature presetcapacitor TC3. The audio intercarrieroscillator is tuned by L2 (a 1501 choke),TC2 and C24.

The TDA8722 is a surface -mounteddevice.

The RC feedback oscillator that consistsof Q4 and the associated componentsproduces an audio signal. I've used thecircuit many times. It's simple and in thisapplication distortion is not a criticalfactor. Q3 is added as an on/off switch,controlled by IC1. The oscillator's outputis fed to the modulator via VR2 and is sentto the mini DIN socket SK3 at fullamplitude.

The unit is designed to be powered byeither four AA cells or a mains adaptor(Fig. 2 shows a suitable circuit), not byrechargeable cells. If the voltage applied tothe unit is excessive, the Wickman fuse F1will blow since zener diode ZD 1 is rated at6.8V.

Power saving is carried out by relayRLY1, Q5 and software in ICI (see later).LD1 is a dual -colour LED that showsgreen when the unit is in operation and redwhen it's in the sleep mode. Powerconsumption is about 150mA when theunit is working, 5mA in the sleep mode -most of the latter is because of the redLED.


ConstructionThe majority of the circuitry is on the mainPCB, with only the pattern -selectorswitches and the LED on the front -panelPCB (see Fig. 3). Both PCBs, alsopreprogrammed PIC ICs, are availablefrom the author. In the prototype F pinswere used to connect the two PCBs. Ifthese are not available, tinned copper wirewill do.

As the main PCB is single -sided, severalwire links are used. One link passes thelength of IC2, between the IC and theboard. There are fifteen surface -mountedcomponents: IC3, R11-14, R27/8, R30,C13, C24, C27-30 and TC3. All the othercomponents are of the conventional wire -lead type.

The prototype is housed in a Vero -stylecase from Fame11, see parts list. The frontpanel is a copper -etched board with thelegends highlighted, though the front panelsupplied with the case can be used.Drilling and making the holes is an exactjob and care is required to get it right.

A small, tinplate screening can isrecommended to fit over the UHF andaudio tank circuits. The dimensions for thisare 15 x 20 x 3 x 0.3mm, see Fig. 4.

Software developmentThose versed in PIC software developmentmay find the following notes of littleinterest. To others they may provide usefulinsight into the work that had to be doneduring evolution of the unit. Setting thebasic specification for the unit was the firststep - the patterns required, how they areselected and the scanning standard, i.e.progressive or interlaced. The latter is themain difference between TV and PCsignals. With interlaced scanning, as usedfor TV, there are 625 lines (Europeanstandard). The first (odd) field starts at lineone and ends half way through line 313. At

Fig. 4: Suggested screening can for the UHF and audio tank circuits.

this point the beam is deflected to the topof the screen, and lines 313 (second half)to 625 are then interleaved between theinitial set of lines, providing the second(even) interlaced field. Interlacingdecreases the flicker that would be noticedwith a non -interleaved picture at the samefield rate.

A close study of the video waveformshowed how the patterns had to begenerated to achieve fully -interlacedscanning. Everything is sequential, whichis nice as a PIC microcontroller also worksin a sequential manner. A clock frequencyof 20MHz is the fastest at which a 16F84can run safely. After internal division thisgives a duty cycle of 200 nanoseconds formost instructions. Thus turning an outputon or off takes 200nsec. The duration of a625 -line scan is 64µsec including theflyback, or 52µsec of forward scan timefor the video. This is the basis on whichpatterns have to be created.

The colour bars were written first,starting with the frame sync sequence. Thishas to include line -equalising andodd/even-field pulses. After the field syncpulses the PIC looks for an odd/even flagso that it can follow an even or oddroutine. Line 17 is the housekeeping line,

Internal view of the PIC-based TV pattern generator.

which is where the control buttons arescanned. At this point we have 52µsec todo all sorts of things. Video starts at theend of line 17. For colour bars this meanstoggling three outputs to provide thecorrect binary information to producethem.

In the original design a thumbwheelswitch was used to select the patterns.Small button switches were chosen for theportable version. This involved aconsiderable change in the housekeepingsoftware in line 17, but plenty of space isavailable. In fact 260 single operations canbe performed in this time.

Another development was power saving.At the start of the setup (power on) aregister is set to count the number of timesthe software loops back to Vert. Afterabout five minutes the PIC goes to sleep,turning off relay 1 and reducing the powerrequirement to 5mA, or virtually zero if thered LED is not used. To waken the PIC,either switch the unit off and on again orpress the colour -bars select button.

The trouble with most microcontrollerchips of this type is that they have 8 -bitdata registers, giving a total of 256 counts.Since each field consists of 312.5 lines,and lines are being counted to performfunctions, the line counter has to be loadedtwice to produce a full scan. This was doneby loading the line counter with 20 hex =32 decimal and decrementing it to zero,then decrementing the line counter againfrom FF hex = 256 decimal to zero. Atzero the sync -only output would be used.Visually the problem was a small kink inthe top part of the screen, at line 32 visual.This was overcome with a small (200nsec)NOP (no operation) pad, which had to beat exactly the right place.

Once the colour bars were acceptable theother patterns were developed. Some weremore difficult than others.

One criticism of this design is thethickness of the vertical lines, especially inthe crosshatch pattern. As mentionedearlier, it takes 400nsec to turn an outputon and off. Thus with a 20in. CRT and avisible horizontal line of 16in., eachvertical line will be 0.12in. wide. But thisseemed to be a small price to pay to keep itsimple.

The author can supply fully -programmed


Parts list

Component

CI, 2C3, 16, 17C4, 6C5, 11, 14, 31C7C8, 9, 10

Specification

15pF ceramic100pF, 10V electrolytic150pF ceramic100nF ceramic1 nF ceramic470nF MKT radial

Order code*

645-990301-7308354-9550354-9641354-9604568-193

C12, 26, 32 47µF, 10V electrolytic 301-7291C13, 28, 31 100nF SMD ceramic size 0603 499-675C15, 22 10pF, 25V electrolytic 301-7357C18-21, 23 100nF MKT radial 218-480C24 22pF SMD ceramic size 0603 722-005C27 lOnF SMD ceramic size 0603 301-9561C29, 30 100pF SMD ceramic size 0603 722-080TC1, 2 4.2-20pF ceramic 108-220TC3 l5-5pF SMD CTZ3 498-981

RI, 23 4.7kQ, MF12 series 514-184R2, 3, 17 47kQ, MF12 series 514-421R4 3.3kQ, MF12 series 514-147R5, 6, 7 3.9kO, MF12 series 514-160R8-10, 20-22, 25 IkQ, MF12 series 514-020RII, 12 5.6kQ, SMD size 0805 554-728R13-15 22kQ, MF12 series 514-342R16 5.6kQ, MF12 series 514-202R18 161M, MF12 series 514-317R19 75Q, MFI2 series 513-751R24 12k52, MF12 series 514-287R26 680Q, MF12 series 513-982R27 1.5k52, SMD size 0603 433-070R28 470Q, SMD size 0603 433-044R30 68Q, SMD size 0603 432-994VR1, 2 4.7kQ, N6 series 643-257

DI 1N4148 885-095LD I 3mm tricolour LED 637-210ZD1 BZX79C6V8 369-433ICI 16F84IC2 CXA1645PIC3 TDA8722Q1, 3,5 BC547 357-054Q2 BC338A 356-979fQ4 BC107 356-270

Fl 500mA Wickman 150-987L2 15pH 513-465RLY1 Sub -miniature relay 175-029X1 20MHz HC49/U 569-902X2 4436 I 9MHz HC49/U 638-500SKI 1.3mm DC socket 224-947SK2 RCA 3 -pin PC13$ 152-396SK3 4 -pin DIN 152-212SWI-6 Miniature PCB SPNO 959-698SW7 SPDT slide switch Maplin FVO1BCase OKW 207-690

* Famell Electronic Components (phone 0870 1200 200) unless otherwise specified.f The BC338A has a different pin out from the BC338, BCE instead of EBC. Only the BC338 is

available from Farnell. So, unless the A version is available, the legs need to be rotated to fit.It seems that two versions of the PCB -mounted RCA phono socket are available. The PCB has

been designed to use both, but because of earthing track requirements one pin must be removedwith the 3 -pin version.

PCB1, PCB2 and ICI (16F84, pre-programmed) are available under order code TVPG1, TVPG2and TVPG3 respectively from Denmo Electronics, 219 Alder Street, Huddersfield, W. Yorks HD21AX. E-mail [email protected]

IC2 (CXA1645P) is available from RS Components under order code 215 5102. IC3 (TDA8722)is available from EuroDis Electronics UK, Bolton. Phone 01204 555 000.

PIC microcontroller chips (see Parts List).

TestingThe instrument is very simple to set up andtest, as the patterns are pre-programmed.After building it, check for any obviousshort-circuits -a couple of very closesupply line tracks were unavoidable.

If the microcontroller chip ICI ismounted in a socket, which is useful forsoftware updates, insert it. Connect anexternal supply (not batteries) with thecurrent limiting set at approximately150mA. Use a scope to check the outputsat pins 1, 2, 17 and 18 of IC1. Compositesync should be seen at pin 2 and squarepulses at the other pins. If no outputs areseen, check at pin 15 to ensure that thecrystal is oscillating. If there are nooscillations, the microcontroller chip maynot have had its internal fuses set correctlyfor 20MHz operation.

Next check for a video output (colourbars) at pin 20 of IC2. If this is present,connect the unit's output to a TV set'sscart input. Adjust TC1 for stable colourbars. If you want to be precise, use afrequency counter to set the oscillator to4-433619MHz.

Select the other patterns and ensure thatthey are OK. There are no otheradjustments for the basic patterns.

Use the scope to check for a reasonablesinewave at the collector of the audiooscillator transistor Q4. If there is nooscillation here, the gain of the BC107transistor used could differ from that of mystock. If necessary adjust the value of R24to achieve oscillation. SW6 is the audioon/off button: check that it stops theoscillator. The software is designed to turnthe audio oscillator on when any patternbutton is pressed.

If the UHF modulator chip has beenfitted, check its RF output by connectingthis to a TV set's aerial input socket (orany other suitable monitoring instrument).Adjustment of TC3 will vary the outputbetween approximately 460MHz and630MHz. If RF is present, adjust VR1 forgood picture quality - be careful not toover -modulate the pattern.

Adjust TC2 for minimum audio buzzwhen the TV sound is turned up. Thenadjust VR2 for a good audio tone, withoutover -modulation. Finally readjust TC2 fora clean tone.

I varied the DC supply over 4-6.5Vwithout any noticeable frequency shift. Butthis is not recommended, as the devices aredesigned to run at 5V.

In conclusionThis instrument was designed over a five-year period, mainly because of difficulty infinding good UHF modulators fromreliable sources. Various software changes,mainly in the power -saving routines, weremade during this time.

The unit is in daily use and has proved tobe very reliable. It would be an asset in anyserviceman's toolbox.


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VALUE CODE PRICE

10 Volts100uF ..CAP118470uF ..CAP291000uF .CAP1192200uF .CAP120

£0.45.£1.20.£1.50£2.10

PER

PACK

16 Volts22uF .CAP121 £0.3533uF ...CAP122 10.3547uF ...CAP123 £0.35100uF ..CAP124 £0.60220uF ..CAP125 £0.80330uF ..CAP30 . £1.75470uF ..CAP31 . £1.75680uF ..CAP32 . 12.10 5

1000uF .CAP33 . £2.102200uF .CAP34 £5.253300uF .CAP35 .15.00 5

4700uF .CAP36 . £6.10 10

2.5 Volts10uF ...CAP37 .10.4522uF ...CAP38 . £0.4533uF ...CAP126 .£0.4047uF ...CAP39 .10.48 568uF .CAP127 .£0.55100uF ..CAP40120uF . .CAP128 .£0.85150uF ..CAP41 . £0.95 5

220uF ..CAP42 . £1.20330uF . .CAP43 £1.40 5470uF ..CAP44 £1.90680uF . .CAP45 . £3.15 51000uF .CAP46 . £3.65101500uF CAP47 13.902200uF .CAP48 .12.003300uF .CAP49 ..£2.204700uF .CAP50 £3.656800uF .CAP51 £3.90

52

2

2

2

105°c Radial Electrolytic CapacitorsVALUE CODE PRICE PER

PACK35 VoltsluF ....CAP130 .£0.403.3uF ..CAP131 £0.404.7uF ..CAP132 £0.4510uF ...CAP52 .£0.5022uF ...CAP53 £0.4533uF .CAP54 £0.50 5

47uF ...CAP55 £0.8568uF ...CAP133 £0.55100uF ..CAP56 .£0.85150uF ..CAP57 10.95 5

220uF ..CAP58 .£1.45 5330uF ..CAP134 .£1.60470uF ..CAP135 .£1.75680uF .CAP59 .£6.50 101000uF .CAP60 .£4.352200uF .CAP61 .£2.45 23300uF .CAP62 £10.004700uF .CAP136 .£3.50 2

50 Volts1uF CAP137 .£0.35 102.2uF CAP138 .£0.35 103.3uF CAP139 .£0.354.7uF CAP 140 £0.3510uF .CAP6322uF . .CAP6433uF . CAP141 .£0.8547uF .CAP65 . £0.85 1068uF CAP142 .£0.90100uF .CAP66 ..£0.85 10220uF .CAP67 .11.75330uF .CAP68470uF .CAP69 £4.35680uF .CAP70 ..£4.901000uF .CAP71 .15.251500uF .CAP143 £4.502200uF .CAP723300uF .CAP144 .£3.25

..105

..105

2

2

VALUE CODE PRICE PER

PACKg3 Votts

0.22uF .CAP145 .£0.450.47uF .CAP73 .10.351uF ....CAP74 ..£0.352.2uF ..CAP75 £0.353.3uF ..CAP76 ..£0.504.7uF ..CAP77 ..£0.35 .1010uF ...CAP78 . £0.5015uF ...CAP79 £0.95 522uF . . .CAP80 .10.7533uF ..CAP81 £0.85 .1047uF ..CAP82 ..£0.95 .1068uF ...CAP83 . £1.30 5

100uF ..CAP84 . £1.20 10150uF ..CAP85 £2.80 5220uF ..CAP86 . £2.80 10330uF ..CAP87 ..£4.00 10470uF ..CAP88 . £525 10680uF ..CAP89 .£5.00 101000uF .CAP90 ..£5.40 5

100 Volts0.47uF .CAP91 £0.50 5

1uF ....CAP92 .£0.851.5uF CAP93 £0.70 52.2uF CAP94 £0.50 53.3uF CAP95 £0.50 54.7uF CAP96 £0.50 510uF CAP97 £0.95 1022uF CAP98 £1.05 1033uF CAP99 £1.55 547uF CAP100....£1.75 10100uF ....CAP101....£2.10 10220uF CAP102. .£6.00 5

470uF CAP103. .£6.00 5

160 Volts2.2uF CAP146. .£0.45 1010uF CAP147....£1.40 10

VALUE CODE PRICE PER

PACK160 Volts... continued22uF CAP148 £1.80 1033uF CAP149 £2.30 10100uF CAP150 £3.25 5

nkyolAs100uF CAP151 £3.25 5

250 Volta1uF CAP152 £0.60 103.3uF CAP104 £1.75 1010uF CAP105 £2.60 1022uF CAP153 £2.30 1047uF CAP106 £4.35 10100uF CAP154 £4.50 5220uF CAP155 £2.00 2

350 Volts1uF CAP156 £0.70 103.3uF CAP157 £1.50 1010uF CAP158 £2.25 1022uF CAP159 £3.40 10

400 VoltsluF CAP107 £2.15 52.2uF CAP108 £2.25 54.7uF CAP109 £3.15 510uF CAP110 £4.00 5

22uF CAP111 £2.50 2

47uF CAP112 £3.50 2

100uF ..CAP160 .£4.00 2220uF ..CAP161 .£7.00 2

450 Volts1uF . CAP113 ..£2.80 52.2uF CAP114 .£3.20 5

4.7uF . CAP115 £4.95 5

10uF ..CAP116 ..£5.50 5

22uF ..CAP117 .£4.15 2

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Powered by 9V battery

Order Code : 24504SPrice : £ 28.00 + vatPostage : £ 3.00 + vat

K.P. House , Unit 15 , Pop In Commercial Centre , Southway , Wembley , Middlesex . HA9 OHB England

Tel : (020) 8900 2329 Email : [email protected] : (020) 8903 6126 Website : http://www.grandata.co.uk


Television Repair / Mod KitsMAKE KIT TYPE CODE& MODEL

ALBA

MAKE KIT TYPE CODE& MODEL

GOODMANS..continued

MAKE KIT TYPE CODEIL MODEL

MITSUBISHI -Continued

MAKE KIT TYPE CODE8. MODEL

PHILIPS -continued1452T PSU ONWAKIT 2029T PSU ONWAKIT CT21AV1BS PSU MITSKIT3 310.32262 PHILKIT8

1427T PSU ONWAKIT 2029TA PSU ONWAKIT CT25A2STX TDA8178S MITSKIT1 310.62264 PHILKIT1

1402 PSU ONWAKIT F16 CHASSIS FRAME GOODKIT1 CT25A3STX TDA8178S MITSKIT1 ANUBIS A SOPS PHILKIT2

1455T PSU ONWAKIT F16 CHASSIS LINE GOODKIT1 CT25A4STX TDA8178S MITSKIT1 CP110 CHASSIS ....SOPS PHILKIT8

1456T PSU ONWAKIT F16 PSU GOODKIT1 CT25A6STX TDA8178S MITSKIT1 G90A CHASSIS SOPS PHILKIT10

1458T PSU ONWAKIT F16 VIDEO GOODKIT1 CT25AVIB PSU MITSKIT3 G90B CHASSIS SOPS PHILKIT10

1459T PSU ONWAKIT CT25AV1BS PSU MITSKIT3 G110 CHASSIS SOPS PHILKIT3

1499Y STANDBY MODKIT37 GRUNDIG CT25AV1BD PSU MITSKIT3 GR2.1 CHASSIS SOPS PHILKIT1

2002 PSU ONWAKIT CUC 7350 GRUNDIGKIT1 CT25AV1BDS PSU MITSKIT3 GR2.2 CHASSIS SOPS PHILKIT1

2009B PSU ONWAKIT CUC 7301/3 CT28AV1B PSU MITSKIT3 D-16 CHASSIS SOPS PHILKIT6

2052T PSU ONWAKIT (BUZ90) PSU GRUNDIGKIT2 CT28AX1BD PSU MITSKIT3 HSM VIDEO SOPS PHILKIT5

2152T PSU ONWAKIT CUC 7301/3 CT28AV1BDS PSU MITSKIT3 JSM VIDEO SOPS PHILKIT4

2099TX STANDBY MODKIT37 (MJF18004) PSU GRUNDIGKIT3 CT29AS1 TDA 8178S MITSKIT2 KSM VIDEO SOPS PHILKIT9

BTV17 STANDBY MODKIT37 CT29A4 TDA 8178S MITSKIT2 LSM VIDEO SOPS PHILKIT7

CTV501 PSU ONWAKITCTV701 PSU ONWAKIT

HINARI CT29A6 TDA 8178S MITSKIT2CT29B2 TDA 8178S MITSKIT2 SAMSUNG

HIT14RC PSU ONWAKIT CI5944 FRAME SAMKIT2

CI6844 FRAME SAMKIT2CTV840 PSU ONWAKITCTV841 PSU ONWAKIT

MAKE KIT TYPE CODEMODEL

CTV485 PSU ONWAKIT JVCC1 -29B3 TDA 8178S MITSKIT2

VIK310 PSU SAMSUNGKITVIK320 PSU SAMSUNGKITAV29SX1EK FIELD 0/P JVCKIT1

AKAI AV29SX1EN FIELD 0/P JVCKIT1

AV29SX1EN1 FIELD 0/P JVCKIT1

AV29SX1PF FIELD 0/P JVCKIT1

CT29B6 TDA 8178S MITSKIT2CT33B3 TDA 8178S MITSKIT2M5 SERIES PSU MITSKIT3

VIK350 PSU SAMSUNGKITVI375 PSU SAMSUNGKITVI395 PSU SAMSUNGKITCT1417 PSU ONWAKIT

CT2159U PSU ONWAKIT

CT2162UNT PSU ONWAKIT

CT2863UNT PSU ONWAKIT

AV29TSIE1 FIELD 0/P JVCKIT1

C14E1EK PSU ONWAKITC14T1EK PSU ONWAKIT

NEI/NIKKAIWINNER 1 PSU SAMSUNGKIT

SHARPCE25 CHASSIS PSU NIKKAIKIT1

DECCA/TATUNG C21ET1EK PSU ONWAKIT

CS21M3EK PSU ONWAKIT

C289FTXN PSU NIKKAIKIT1C28F41FXN PSU NIKKAIKIT1

51CSO3H PSU SHARPKIT151CSO5H PSU SHARPKIT1

TVC563 STANDBY MODKIT37 59CS03H PSU SHARPKIT2

MATSUI PANASONIC 59CS05H PSU SHARPKIT2

GOLDSTAR 1455 PSU ONWAKIT IC561 TDA 8175 PANKIT1 59CSD8H PSU SHARPKIT2

CF25A5OF FRAME MODKIT36 1498 PSU ONWAKIT TX25XD60 VERT OUTPUT PANKIT2 59DS03H PSU SHARPKIT3

CF25C22C FRAME MODKIT35 2086 PSU ONWAKIT TC28XD60 VERT OUTPUT PANKIT2 66CS03H PSU SHARPKIT2

CF28A5OF FRAME MODKIT36 2098 PSU ONWAKIT TX28XD70 VERT OUTPUT PANKIT2 66CS05H PSU SHARPKIT2

CF28C22F FRAME MODKIT35 21V1N (BUZ90) PSU GRUNDIGKIT2 TX29XD70 VERT OUTPUT PANKIT2 66CSD8H PSU SHARPKIT2

CF28C28F FRAME MODKIT36 21V1T(MJF18004) PSU GRUNDIGKIT3 TX-W26D3 VERT OUTPUT PANKIT2 THOMSONCF29C42F FRAME MODKIT35 TVR180R/T/2080 STANDBY MODKIT37 35029400 THOMKIT2

PHILIPS 35065920 THORNKIT1

GOODMANS MITSUBISHI 310.10708 PHILKIT3 FV70 PSU THORNKIT1

147TT PSU ONWAKIT AV1 SERIES PSU MITSKIT3 310.20491 PHILKIT2 ICC7 CHASSIS TDA 8178FS THOMKIT1

149T PSU ONWAKIT CT1M5B PSU MITSKIT3 310.20496 PHILKIT10 ICC7 CHASSIS FRAME THOMKIT3

1430RA PSU ONWAKIT CT21M5BT PSU MITSKIT3 310.31994 PHILKIT6 ICC8 CHASSIS ..TDA 8178FS THOMKIT1

1430RS PSU ONWAKIT CT25M5BT PSU MITSKIT3 310.32252 PHILKIT5 ICC8 CHASSIS FRAME THOMKIT3

1430RW PSU ONWAKIT CT21A2STX TDA 8178S MITSKIT1 310.32253 PHILKIT4 ICC9 CHASSIS ..EAST/WEST THOMKIT4

1450T PSU ONWAKIT CT21AX1B PSU MITSKIT3 310.32254 PHILKIT9 R3000 PSU THOMKIT2

1455TS PSU.. ONWAKIT CT21A3STX TDA 8178S MITSKIT1 310.32255 PHILKIT7 R4000 PSU THOMKIT2

2019R PSU ONWAKIT TX92F CHASSIS..EAST/WEST THOMKIT4

ORDER CODE PRICE ORDER cocoa PRICE ORDER CODE PRICE ORDER CODE PRISE ORDER CODE MICE_

GRUNDIGKIT1 £ 10.50 MITSKIT3 £ 6.00 PANKIT2 £ 9.00 PHILKIT6 £ 5.50 SHARPKIT2 £ 11.00

GRUNDIGKIT2 £ 10.50 MODKIT35 £ 9.50 PHILKIT1 £ 7.60 PHILKIT7 £ 7.60 SHARPKIT3 £ 9.00

GRUNDIGKIT3 £ 10.50 MODKIT36 £ 5.00 PHILKIT10 £ 8.50 PHILKIT8 £ 4.25 THOMKIT1 £ 7.00

GOODKIT1 £ 11.00 MODKIT37 £ 6.50 PHILKIT2 £ 2.50 PHILKIT9 £ 7.50 THOMKIT2 £ 12.00

JVCKIT1 £ 11.00 NIKKAIKIT1 £ 12.00 PHILKIT3 £ 4.00 SAMKIT2 £ 8.00 THOMKIT3 £ 9.00

MITSKIT1 £ 3.00 ONWAKIT £ 12.00 PHILKIT4 £ 4.25 SAMSUNGKIT £ 16.00 THOMKIT4 £ 4.00

MITSKIT2 £ 15.00 PANKIT1

I£ 11.00 PHILKIT5 £ 5.75 SHARPKIT1 £ 11.00 THORNKIT1 £ 12.75

*Codeless set-upBrandPanasonic TVSony TVPhilips TVHitachi TVMitsubishi TVNokia TVSamsung TVToshiba TVFerguson TVGrundig TV

Remote ControlsBrand Replacement Remote ControI

*Teletext and Fastext *Pre -Programmed for the latest models * Replaces broken and lost remotesOrder Code Brand Order CodeRCUNIO1M Grundig TV RCUNI10

RCUNI11RCUNI12

RCUNIO2MRCUNIO3MRCUNI04RCUNI05RCUNI06RCUNI07RCUNI08RCUNI09RCUNI10

Sanyo TVSharp TVGoodmans/Alba/Bush TVMatsui/Hinaril/Orion TVSky DigitalOn DigitalSatellite

Price : £7.50 + vat eachBuy any 5 of the above and get a Special Price of £ 7.00 + vat each

RCUNI13MRCUNI14MRCUNI15RCUNI16RCUNI17

We stock Replacement Remote Controls for over 23,000 different modelsPrices start from £ 5.50 + vat each

Please call for a copy of our latest Remote Control Catalogue on 020 8900 2329


KEJI\JIT7 Konig_ Electronic KEL.m.iir-7--.,I ELECTRONIC] Spares ELECTRONIC

To mark our new association with Konig Electronics we are glad to offer thefollowing Konig Remote Controls at Special Prices !!!

Konig No. Model/Part No. Konig No. Model/Part No.BANG 8. OLUFSEN PHILIPS..continued

IR 9248 BEOLINK100 IR 9553 RC5410 , RC5420 , RC5801

BEKO IR 9556 RC5901 , RC5902 , RC5903 , RC5904,RC5905

IR 9398 RC51321 , RC51331 , RC61331 IR 9710 RC7507 , RC8205 , RC9057 , RC9133IR 9864 RC7512 RC7535

DAEWOO,

IR 9840 DMQ14A1 , DMQ20A1 , DMQ2195 SAMSUNG

IR 9584FERGUSON

RCU1734 , RCU1742 , T742 ,T752 , T758

IR 9546IR 9432

RM100RM104 , CX532WT , CX534WT , CX5312W

IR 9594 RH880 , T789 SANYOIR 9325IR 9259

RH885RHT01 , RHT30

IR 9457 JXBA , JXFF , RC307 , RC317 , RC318 ,

RC321 , RC612 , RC625 , RC628

IR 9639 RHT10 IR 9530 JXCL , JXCR , RC258 , RC642

IR 9719FUNAI

30T1 , 30T2 , 31T1

IR 9139IR 9460

JXGA , JXGE , RC700 , RC702JXGT, JXGW, JXGY, JXLB, JXLG, RC711, SO2

IR 9403IR 9854

GOLDSTAR105-068 , CBT2190E , CBT4902 , CBT990505-219J , 105-224V , 105-229H , 105-2300

IR 9487

IR 9711

SHARPC1421 , C2021 , CV2121 , CV3707 , CV3709CV3710 ,DV1416 , SV2044 ,SV2145RRMCG0739BMSA ,G1014BMSA

GRUNDIG RRMCG1023BMSA , G1036BMSAIR 9529 CUC5301 , CUC5302 IR 9788 RRMCG1031BMSA , G1046BMSAIR 9614 CUC5200 , CUC5303 , CUC5310 RRMCG1048BMSA , G1050BMSAIR 9749IR 9715

TP715 , TP770 , TP771 , TP800 , TP900TRC1 , TRC2

IR 9321SONY

RM640 , RM641,RM641A,RM642AHITACHI IR 9336 RM650 , RM651 , RM652 , RM654

IR 9602 CLE871A , CLE871B , CLE874A , CLE874B IR 9448 RM656 , RM677 , RM687B , RM687C , RM717IR 9476 CLE876A , CLE876B , C1405 , C1414 , C2114 IR 9123 RM670 , RM671 , RM672 , RM673

IR 9477C2514 , CT2116CLE876C , CLE876D , CLE876E , CLE876G

IR 9442 RM681 , RM682 , RM683 , RM684 ,RM685 ,

RM686 , RM698IR 9982 CLE922A , CLE922B IR 9452 RM694 , RM820 , RM828 , RM834 , RM841IR 9576 CPT1556 , CPT1557 , CPT1560 , CPT1561 ,

CST1430 , CST1435 , CST1560IR 9441IR 9443

RM689 , RM816 , RM817 , RM826RM830 , RM831 , RM832 , RM842

IR 9575 CPT2155 , CPT2164 , CPT2558 , CPT2564 ,CPT2566 , CPT2669 , CPT2785 , CPT2870

MATSUI

IR 9451IR 9511

RM833 , RM837RM615 , RM620 , RM625 , RM630 , RM631 ,

RM632 , RM633 , RM634 , RM635IR 9490 076L067240 , 2076R , 2092T IR 9871 RM836 , RM839 , RM883 , RM886

NOKIA TELEFUNKENIR 9573 FS4/1 , FS4/2 , FS5/1 , FS9 ,FS10

ORIONIR 9624 FB330, FB340, FB345, FB1330, FB1340 ,

THOMSONIR 9640 RC37 , RC56 , RC565633 , RCQ

PANASONICIR 9639 14GM53 , 14GM56 , 14MS70 , 21DS70 ,

21MG51 , 21MS76

IR 9826 EUR37211, EUR50100 ,EUR50370 EUR51140 TOSHIBATNQ8E421 , TNQ8E0422 , TNQ8E0428 IR 9853 CT9493 , CT9511

IR 9834 TNQ8E0461 IR 9953 CT9626 , CT9784,CT9785,CT9859PHILIPS

IR 9510 RC5002 , RC5140 , RC5154 , RC5240 ,

£ 6.50 + vateach

Buy 5 or more£ 6.00 + vat each


K C:3\11E7 Konig ElectroniceLec-rr9Drvic Spares

Replacement Line Output Transfo

ECTPIONIIC

Make Part No.

FAT 3843...1

FAT 30106....

If you cannot find the Konig Spares you want in this advert please call us on020 8900 2329 as this is just a small selection

ur Code Price

..0T204 14.00

_OT172 13.50

_OT226 14.50

_OT200 12.50

_OT328 16.00

_OT330 16.00

LOT41 ..E 15.50

_OT433 12.00

_OT562 _I 15.50_OT129 14.00

_OT125 _I 16.00_OT132 15.00

OT284 14.00

Philips AT 2079/21 , AT 2078/21 , TFB 4090 AD FAT 30179 ..LOT395 12.00

Philips AT 2079/17 FAT 30171 ..LOT288 ....E 14.00

Philips AT 2079/23 FAT 30170 ..LOT289 13.00

Sony 1-439-332-42 FAT 3925....LOT100 ....E 12.00

Sony 1-439-493-11 , 1-439-423-11 , 1-439-423-12 FAT 30089 ..LOT369 15.50

This is just a selection of Konig Line Output Transformers .

Please call us on 020 8900 2329 for any that are not listed.

..E 14.00

Philips AT 2079/23 FAT 30170 ..LOT289 13.00

Sony 1-439-332-42 FAT 3925....LOT100 ....E 12.00

Sony 1-439-493-11 , 1-439-423-11 , 1-439-423-12 FAT 30089 ..LOT369 15.50

Replacement Televison Mains Switches

This is just a selection of Konig Line Output Transformers .

Please call us on 020 8900 2329 for any that are not listed.

KN658304

Replacement Televison Mains Switches

ik IA4

KN658304

For Sony and SonyPrice : £ 2.50 + vat

ik IA4

KN668500

For Sony and SonyPrice : £ 2.50 + vat

Replacement for Grundig 29703-291.07Price : £ 2.50 + vat

KN668800N650

eplacement for Grundig 29703-291.07Price : £ 2.50 + vat

4 . intFor Daewoo

Price : £ 2.50 + vat

KN668800

If you cannot find the Konig Spares you want in this advert please call us on020 8900 2329 as this is just a small selection

4 . intFor Daewoo

Price : £ 2.50 + vatR

4 . intFor Daewoo



Aerial & Digital Satelitte AccessoriesSLx Aerial Amplifiers

Now with built in Digital ByPass - Operates with SkyTM DigiEye

Class leading noise figure of 4dB or less

6dB signal amplification on all models

25mA line powering for masthead amplifier(Only on SLX4B , SLX6B , SLX8B)

Description2 Way - No Bypass

2 Way - With Bypass

4 Way - No Bypass

4 Way - With Bypass

6 Way - No Bypass

6 Way - With Bypass

8 Way - No Bypass

8 Way - With Bypass

Order CodeSLX2

SLX2BSLX4

SLX4BSLX6

SLX6BSLX8

SLX8B

Price£ 8.00 + vat£ 9.25 + vat

£ 13.00 + vat£ 14.00 + vat£ 18.00 + vat£ 19.00 + vat£ 18.50 + vat£ 20.00 + vat

Coax PlugAluminium

Order Code : PLG51

Bag of 10Price : £ 1.25 + vat


Screw TypeCoax Plugs

Order Code : PLG62



SLx Link EyeAllows control of SkyTM D gibox via the signal feed for

second TV

Order Code : 27833R1 - 9

£6.50 + vat each

10 - 24£ 5.50 + vat each

Amstrad DRX100Tuner Repair Kit

Order CodeSATKIT35

Price£ 1.40 + vat

Twist On FConnectors

OrderCode:PLG101Bag of 10



Coax CouplerSocket to Socket

Order CodePLG54

Bag of 10Price : £1.50 + vat

SkyTM Digital TV Link EyeOrder Code : TVLINKEYE

Price£ 10.75 + vat

5+£ 7.99 + vat each

10+£ 6.99 + vat each

Amstrad DRX100Power SupplyReliabilty Kit

Order CodeSATKIT36

Price£ 12.00 + vat

Amstrad DRX100Power Supply

Repair Kit

Order CodeSATKIT37

Price£ 13.50 + vat

DLit masmeau "mperiersUHF TV antenna pre amplifier designedfor the professional aerial installer

15d8 gain masthead amplifier ideal formajority of domestic installations

26dB gain masthead amplifier for longercable runs (loss of more than 3dB) or ifconnected to passive splitters

Requires 12V DC power supply via downlead either viadedicated power supply unit or from a distribution ampli-fier with line powering

SLx 15dB Gain Masthead AmpOrder Code : 27830R Price : £ 4.30

+ vat

SLx 26dB Gain Masthead AmpOrder Code : 27831R Price : £ 4.50

+ vat

Coax CouplerPlug to Plug

Order CodePLG55

Bag of 10Price : £1.50 + vat

Y SplitterInductive 3 way

6Order CodeYSPLITTER

Price : 40p + vatBag of 10


SLx Amp By Pass KitFor use with aerial amplifiers and SkyTM Digibox

Allows for operation of Link Eye inconjunction with a distributionamplifier

Order Code : 27829RPrice : £ 5.00 + vat

Grundig GDS200Digital Satellite Receiver

Repair Kit

Early psuMODEL DSO - 0385 REV C

Order Code: SATKIT34APrice : £ 10.00 + vat

Grundig GDS200/300Digital Satellite Receiver

Repair Kit

LATER psu TYPE REV 03DSO - 0375 REV ADSO - 0385 REV 5

Order Code: SATKIT34BPrice : £ 10.00 + vat

Check out our New Online Catalogue at

www.grandata.co.ukThis advertisement is just a selection of our stock.

Please contact us if you cannot find the part you are looking for.

* Please add £1 p+p and VAT to all orders (Unless Otherwise stated) * All components are brand new* We accept payment by Access , Switch , Visa , Cheque and Postal Order

* All prices quoted are subject to availabilty and may be changed without prior noticeE & OE

K.P. House , Unit 15 , Pop In Commercial Centre , Southway Wembley , Middlesex . HA9 OHB England

: [email protected]: http://www.grandata.co.uk

Tel : (020) 8900 2329 EmailFax : (020) 8903 6126 Website

Wanted: CRT type A51EAL20X01 for aFerguson set, Model 51A2. Phone C. Harton 01872 271 407 (Truro) or [email protected]: Circuit diagram for the SonicaIndustries Ltd. 17in. colour monitorModel Imagevision 17-650SD. All costspaid. There appears to be a power supplyfault. Cyril Randle, 1 Corn Hill, OrchardHills, Walsall WS5 3DT. Phone 01922620 456 or e-mail [email protected] disposal: Service manuals (severalhundred TV, video and audio), valves andspares from the 1970s/1980s. Free tocollector or pay postage. Also a completeDecca Bradford chassis (no cabinet).Phone Rod Marriott on 01422 374 621(Halifax).Wanted: Does anyone have anyinformation on the vintage Sinclair UHFflatscreen pocket TV - there is no modelnumber visible? Also, does anyone knowthe component changes required to enablea Philips KT3 chassis, 20in. version, to beused with a 14in. tube. Or has anyone agood 14in. KT3 full remote -controlchassis for sale/disposal? R.I.E. Payne, 13Molyneux Road, New Milton, HantsBH25 5AU. Phone/fax 01425 617 786.Wanted: M50431-101SP microcontrollerchip for a Samsung Model CB528-2SE(P54S chassis). Owen 0 Reilly, Belfield,Gaybrook, Mullingar, Co. Westmeath,Ireland. Please phone or text 00353879843500 or [email protected] sale: Back issues of Televisionmagazine. Phone Geoff Bayliss on 01443405 169.Wanted: Scrap main and CRT PCBs forthe Mitsubishi Model CT25M5BT (EE4chassis). Must have good LOPT andTEA5101B CRT drive chip. MarkKillingback, Threeways, Westend,Saxlingham Thorpe, Norwich, NorfolkNR15 1UE. Phone 01508 499 009 or [email protected]: Service manual and/or circuitdiagram for the Microvitek Pro -Scan17SX computer monitor. Also any tips onpower supply faults as this seems to be thesite of the failure. Phone Arthur Taylor on1202 739 157 (Poole, Dorset) or [email protected]

The help wanted column is intended to assist readers who require apart, circuit etc. that's not generally available. Requests arepublished at the discretion of the editor. Send them to the editorialdepartment - do not write to or phone the advertisementdepartment about this feature.

WANTEFor disposal: A Yupiteru MVT-7100scanner radio and a 6in., 10MHz Scopexoscilloscope. Offers to Don Clark on01474 325 910 (Gravesend).Wanted: U -View television books andCDs. Books 2 and 4 and CD-ROMS 6 and7. Also an MZC84328 chip (IC13) for theFerguson TX89 chassis and anMB88503H-565G subcontroller chip(IC002) for the Sony AEI chassis. PhoneGraham Richardson on 01904 692 978(York) or [email protected]/for sale: Require a MazdaCRM141/142 round CRT for a restorationproject. Also a Mitsubishi 37C1 37in. TVset. Have for sale various EmiscopeCRTs. Phone Leslie Hine on 01229 582557 (Cumbria) or [email protected] sale: A C1-5 Universal oscilloscope,including manual and also severaloscilloscope books. Mrs M.C. Pearson,Westbury, 81 Valley Drive, Kendal,Cumbria LA9 7AQ. Phone 01539 722056.Wanted: Can anyone supply or lend me aservice remote -control unit for theGoodmans Model 206NS? Apparently it'sno longer available. All expenses paid. S.Whitson, CUTV, 14 Dalkeith Road,Edinburgh EH16 5BP. Phone 0131 6672426.Wanted/for disposal: Require an AvoEA113 electronic multimeter for spares.Have for disposal a CRT and manual forthe Telequipment Model D52oscilloscope. Stan Hassell, Kismet,Woodlane Crescent, Falmouth, CornwallTRI1 4QS. Phone 01326 312 901.Wanted: For spares, non -working Quad405 or 405-2 power amplifiers, Quad 44control units and Quad FM3 tuners. PhoneMike on 01758 613 790.Wanted: Information, parts etc., in factanything to do with Philips car recordplayers dating from the late 1950s andearly 1960s. Martin Randall, AshcroftVideo, 3 Ashcroft Road, Cirencester,Gloucestershire. Phone 01285 658 715 ore-mail [email protected]: Does anyone know or have a listof code numbers for the universal remote -control unit TV Control 4, branded STM,part no. 56-52-24-74, originally supplied

by Akai Australia? Please fax Andy on0011 61 88962 2909 or [email protected]: Training manual, part no.VRD9302D101, for the Panasonic K VCRdeck, and/or video tape or service manualfor Models NV-SD30/40. Please phoneEric Verity on 01202 874 328.Wanted: Remote -control for the ToshibaVCR Model V727B, conditionunimportant.Allan Crathome, 2 Harden Close, WalsallWS3 1BU. Phone 01922 401 130.

Make sure of yourcopy of TelevisionIt can be difficultfinding a copy ofTelevision atlocalnewsagents. Thenumber ofmagazines beingpublished keepsincreasing, whichmeans thatnewsagents haveless shelf spacefor the display ofindividual titles.Specialistmagazines inparticular getcrowded out.

TO, pod., ,.ors iu peopl esp., eltarost

TELEVISIONAND HOME ELECTRONICS REPAIR

0,104.0 1001 23.10

orPrrnmilfriPanasonic Euro-7 chassisPic -based pattern generatorMemory technologydevelopment

There's a solution to the problem. Mostnewsagents provide "shop -save" and/orhome -delivery services. There's no chargefor a shop save. You simply ask yournewsagent to order a copy for you: it willbe kept on one side each month ready foryou to collect. Home -delivered copies areordered in the same way, but generallyincur a delivery charge.A newsagent can order any magazine for

you, whether or not the shop normallystocks it.If you buy your copies of Television froma newsagent and want to make sure youget every issue, just ask at the counter.


Thomson's ICC 17technologyPart 4 of Mark Paul's description of the circuit technology used in this chassisdeals with the microcontroller, signals switching and audio sections

In this concluding instalment in theseries we'll take a look at themicrocontroller system, signals

switching and the audio section ofthe chassis. The microcontroller chip,IR01, belongs to the SGS/ThomsonST92 family. It's an 80 -pin flat -packdevice which is mounted on thesolder side of the main PCB. Itcontrols all functions via a single I2Cbus and several in/out ports. Aninnovation with the ICC17 chassiswas the integration of the teletextdecoder into the microcontrollerchip.

Microcontroller systemAs mentioned in Part 1 (July) themicrocontroller chip is not poweredin the standby mode. This is done tosave power. Because of this, a wake-up system is required, see Part 1.When the set has been brought out ofstandby, IRO1 and the associateddevices are powered by the +5V upsupply, which comes from pin 9 ofthe TDA8139 chip IP95 (see Fig. 1).This supply is fed to pins 10, 34 and52 of IR01. IP95 also provides thereset for pin 54 of IR01. The resetline goes from low to high some40msec after the voltage at pin 9 ofIP95 reaches 5V: the delay isproduced by CP98 (see Fig.2 July).

Detection of a mains supply or lineoutput stage failure leads to the`power fail' line (at the collector ofTP86) going from low (normal state)to high. This line is connected to pin27 of IRO1 which, when it detects afault condition, takes pin 4 of IP95low, switching off the 8V supply(which is used by the timebasegenerator circuitry in IV01). Theswitch -off command appears at pin

39 of IR01, and is fed to IP95 viaTR60. The control line from TR60 islabelled PO. TR60 also takes thereset line low.

IRO1 has a 4MHz crystal, QR01,connected between pins 11 and 12.The frequency is used as a referenceto generate an internal clockfrequency of 22MHz by means of avoltage -controlled oscillator and aphase -locked loop. The PLLcomponents (RR95, CR95 andCR97) are connected to pin 55 ofIR01.

The microcontroller chip works inconjunction with two memory chips,an EPROM (IR02) and an EEPROM(IR03). The device used in the IR02position has a capacity of 512Kbytes:it stores IROl's operatingprogrammes and the service -modedefault values. There are sixteenaddress lines and eight data linesbetween IRO1 and 1802, also threecontrol lines that are used for addressbus extension. The EEPROM IR03has a capacity of 1Kbytes and is usedto store the user adjustable values(brightness, contrast, colour etc.),channel tuning information and thestandby status information. It'sconnected to IRO1 via the I2C bus,which also provides communicationwith the video/deflection processorchip IV01, the audio processor chipIS40 and the tuner. IRO l's I2C pinsare 32 (clock) and 33 (data). The busfrequency is 80kHz. When a deviceconnected to the bus fails to send anacknowledgement to IRO1, thestandby LED GEO I will produce therelevant fault code (see later).

The keyboard buttons are arrangedin a two by two matrix which isconnected to IRO1 at pins 21-24.

When a button is pressed, therelevant key -in line goes low. IRO1detects this change and generateskey -scan pulses (approximately12msec) to determine which key hasbeen pressed. The infra -red remote -control receiver GKO1 is alsomounted on the keyboard module.It's powered by the U stby supply,stabilised by the 5.1V zener diodeDK01. The output is connected to pin25 of IR01. The panel -button and IRsignals are used by the wake-upcircuit to bring the set out of thestandby mode. This was described inPart 1.

IRO1 requires two inputs togenerate on -screen menus, VSYNCat pin 48 and HSYNC at pin 49. Theformer comes from transistor TF01(see Fig. 8, August), the latter frompin 1 of the LOPT (see Fig. 6,August) via attenuator networkRR82/81. A frequency multipliercontrolled by the componentsconnected to pin 53 (CR92, RR93,CR93) is used to determine the pixelgrid for the menus.

TeletextIRO1 incorporates all the circuitryrequired to process teletext data andproduce text and graphics fordisplay. Composite video(CVBSTXT) is fed to pins 60 and 61via CR98 (82pF) and CR99 (0.47µF)respectively. It comes from emitter -follower TV10 (BC846B), whichtakes its feed from pin 54 (selectedCVBS output) of IV01. A PLL isused to regenerate the teletext clock:its filter components CR96 and RR96are connected to pin 57.

Video programming system(VPS/PDC) information can be


12Vo

IP95

From AVS1, pin 8 10k

From AVS2, pin 8 10k

TP71

CVBS from TV10

PO

330p 330p

DR231N4148

8V

RP96CR10

1k47

RR10

10k

10k

RR53 RR526k8 6k8

Vcc

TR23BCR141

CR98 82p

Power fail RR86from TP86 470

II

1k

37

36

60

CR99 0.47

II

RR96 15k57

MIL-C17:96AA/-°2n2

2

RR872k2

CR411n

extracted from line 16 of field oneand wide-screen signalling (WSS)information from line 23. The signalfed to pin 61 is used for the former,the signal fed to pin 60 for the latter.A voltage -controlled oscillator andPLL are used to extract the WSSinformation: tuning is provided byRR90, which is connected to pin 50,and filtering by CR90, RR91 andCR91, which are connected to pin51.

Menu or teletext text/graphics issent to IVO1 in RGB form from pins47, 46 and 45 respectively, with fastblanking from pin 44.

Timer modeIn the timer mode pins 19 and 20 ofIRO1 are low and pin 39 is high.When pin 19 is in this condition

Vcc

LR20

34

IRO1

9

2

St

5

TR40BCR141

TR13 and TR15 (see Fig. 1) are offand the red standby light remainsilluminated. Power for the infra -redreceiver and the front -panel keys isprovided by the U stby line, withzener diode DKO1 (5.1V) forregulation.

With pin 20 low TR20 is off, TP71is on, TP67 is off (see Fig. 2, July)and the current flow via the LED inthe optocoupler ceases. Thisunbalances the input to IP20, itsoutput at pin 7 rises towards 6V andthe main power supply starts up.

With pin 39 high, TR60 is on andpin 4 (PO) of IP95 is low. The 8Vsupply at pin 8 of IP95 is thusswitched off.

On modeThe following conditions apply in the

0.1

CR0482p

0

TCR03

Audio mute

100

100

We

4k7

RR154k7

Vcc

DR20

DR24

10k

TR20TC113ZK

U stby

Stby onto TP71

BRO1 pin 9(to front panel)

TR15RR14 BC856B22k

TR13BCR141

RR16100

BRO1 pin 6(to front panel)

0.1

stby

Fig. 1: Microcontroller circuit-ry referred to in the text.

on mode. When the CRT is warm,pin 19 of IRO1 goes high. TR13 andTR15 switch on and the red standbylight goes out. The IR receiver andfront -panel keys continue to besupplied by the U stby line. Pin 20 ofIRO1 remains low. Pin 39 goes low,TR60 switches off and pin 4 of 1P95goes high, switching on its 8V outputat pin 8. IV01 and the green front -panel LED are powered. Normalpower supply regulation is initiated,as described in Part 1.

Other pins of IRO1Various other pins of IRO1 are worthnoting, as follows.

Pin 28 (mute): This pin goes low tomute the sound when changingchannels, during automatic and


manual programme search routines,when the remote -control unit's mutekey is pressed, when the set isswitched on from cold, when the setis switched off using the mainsswitch, when switching to standbyvia remote control and when the setis in the standby or alarm mode.

Pin 29 (MSP reset): When the set isswitched on or when changingchannels this pin produces a 5mseclow-level pulse to reset the audioprocessor chip IS40.

Pin 30 (format detect): This pin isused to tell IRO1 whether a 4:3 or awidescreen tube is fitted. When thepin is connected to 5V via RR44 theCRT is a 4:3 type. When the pin isconnected to chassis via RR48 thetube is a 16:9 type.

Pins 36-37 (AVS2/1): These pins arefed with the voltage at pin 8 of thetwo scart sockets AVS2 and AVS1respectively, via resistive attenuatornetworks. A voltage between 1-1.5Vat either pin indicates a 16:9 -formatpicture, a voltage between 3-3.5V a4:3 -format picture.

The earthy end of the attenuatornetworks is connected to chassis viatransistor TR23, which is switchedoff in standby (when there is no +5Vup supply). The voltage at pin 8 ofthe scart sockets can then be used toforce the set on, via RR52/RR53 anddiode DR23, which is connected tothe base of transistor TP71 in thepower supply. TR23 is held on whenthe set is on.

Pin 40 (AV3 port): The output atthis pin is used, with sets that haveAV sockets at the front, to switch theBA7604N chip IX01 between AV2and AV3 inputs. High selects AV2signals, low AV3 signals.

Pin 41 (P switch): The output at thispin is used to switch TL55 in the lineoutput stage (see Fig. 5, August) toprovide additional scan -correctioncapacitance. A low at pin 41 means16:9 or zoom 1 mode, a high at pin41 centred 4:3 mode.

Pin 42 (trap information): Theoutput at this pin is used to changethe tuning frequency of the visiontrap in the sound IF section.

Pin 43 (format/BCC): The PWMoutput at this pin is fed to TL59 inthe line output stage (see Fig. 6,August) to adjust the beam -currentlimiting and average white fordifferent tube types and pictureformats.

Fault -code signallingThe red standby LED is used toprovide fault -code signalling. Thisarrangement was adopted as beingeasiest to implement when the I2Cbus has stopped operating and thevoltages produced by the deflectionstages are missing. Fault conditionsare indicated by a two -digit numberwith a pause for separation (seeTable 1). The indication is repeatedat least four times. A maximum of 81codes can be shown in this way.

Note that the chassis uses a bi-coloured standby LED. Thus thecolour displayed when signalling afault may not be just red. If theswitched +8V supply is present at pin8 of 1P95, orange and green may bevisible.

Signal switchingThe ICC17 chassis is equipped withtwo scart sockets (AV1 and AV2)and, depending on cabinet design,optional front -facing video and audioinput phono (cinch) and S -VHSsockets (AV3). Switching betweenthe different signal sources is carriedout by the signals/deflectionprocessor chip IV01 and the audioprocessor chip IS40. In additionIX01 (BA7604A) provides switchingbetween AV2 and AV3 sources.IR02 controls the switching, via theI2C bus and its AV3 port (pin 40).

Scart socket AV1 has compositevideo in at pin 20, red in at pin 15,green in at pin 11 and blue in at pin7. These inputs are capacitivelycoupled to pins 29, 41, 42 and 43respectively of IVOL The fast -blanking input at pin 16 of AV1 isdirect coupled to pin 44 of IVO1.

The composite video or luminanceinput at pin 20 of AV2 is capacitivelycoupled to pin 10 of IX01, withDX59 for clamping and CX58(27pF) to limit the frequencyresponse. The chroma input at pin 15is direct coupled to pin 1 of IX01.

The AV3 composite video orluminance input is capacitivelycoupled to pin 8 of IX01. In earlierproduction this input was clamped byDX62, which was subsequentlyreplaced by CX64 (47pF). The AV3chroma input is capacitively coupledto pin 3 if IX01.

After decoding RGB signals or theswitching voltage at pin 8 of the scartsockets IRO1 sends three bits ofinformation (INA, INB and INC) toIVO1 via the I2C bus. Depending onthe state of these bits, IVO1 selectsand processes the required videoinput. For AV2/3 switching, pin 40of IRO1 sends a control signal to pins4 and 7 of IX01. This is high forAV2 and low for AV3.

The CVBS output from the tuner isalways present at pin 19 of scartsocket AV1. It comes from pin 26 ofIV01 via the emitter -followertransistor TX15 (BC547B).

The CVBS signal selected by IVO1appears at pin 54 of this IC and is fedvia emitter -follower transistor TX45(BC547B) to pin 19 of scart socketAV2. Two bits, CS1 and CSO, via theI2C bus determine which signalappears at pin 54 of IV01.

The collectors of TX15 and TX45are fed from the +8V supply via thecurrent -limiting safety resistor RX17(1052).

Audio signal processingThe ICC17 chassis has been designedto cater for various audiorequirements from mono sound toDolby Pro -Logic. Basic audio signalprocessing is carried out by either anMSP3400C IC or, where Nicamsound processing is required, anMSP3410D IC (IS40). This takes itsinputs from IV01. For stereo soundthe audio outputs drive a TDA7269dual audio -amplifier chip, IS80.Where Dolby Pro -Logic or VirtualDolby processing is required, theMSP chip is replaced with either oftwo separate modules, AMDP 1700100 for Dolby Pro -Logic or AMVD19100 00 for Virtual Dolby. Anauxiliary power module, AM/DP17000 00, provides the extra speakerdrives for Dolby Pro -Logic.

A new feature introduced with thischassis is the Automatic VolumeLimiter, which is switchable. Whenactivated, the volume remainsconstant during channel surfing andadvertising periods.

IS40 has two supplies, 8V at pin 39for analogue signal amplification andprocessing, and +5V ON at pins 7, 18and 57 for digital signal processing.Both inputs are well filtered toprevent switching noise interferencefrom the chip. The only otherimportant item here is an 18.432MHzcrystal (QS40) to provide the maininternal clock signal. It's connectedto pins 62/3.

After level -shifting by TS01 thedemodulated FM/Nicam input is fedto pin 58 of IS40. It's then passedthrough a gain -controlled amplifierto the complex digital demodulationand decoding block, where allavailable FM mono, FM stereo andNicam signals are detected andprocessed.

IS40 is controlled via the I2C bus(SCL pin 9, SDA pin 10). Thisprovides signal selection and bass,treble, stereo base widthenlargement, pseudo stereo, balanceand master volume adjustment as


required. The stereo outputs are at pins28 (right) and 29 (left).

The TDA7269 stereo output chip hasa 33V supply at pin 3 and can provide2 x lOW RMS at 80. It's internallyprotected against shorts and thermalrunaway. IRO1 and a single level -converter transistor (TS81) control theaudio mute function.

Dolby variantsFor Virtual Dolby operation the on-board processor (IS40) is replacedwith a sub -module, the remainder ofthe audio circuit being the same. Thesub -module contains an MSP3410Daudio processor (IS100) and aDPL3518 Dolby processor (IS200).The latter decodes the digital dataproduced by IS100, creating VirtualDolby data that's returned to IS100for further processing.

In Dolby Pro -Logic models the on-board processor and stereo amplifierare replaced by a sub -module and anauxiliary audio power amplifierboard. The Pro -Logic sub -moduleuses the same IC complement as theVirtual Dolby version, but hasadditional interconnections betweenthe ICs and extra sockets. Theauxiliary audio power amplifier board

Table 1: Failure codes indicated by the standby LED

Code Error description

10 Child -lock mode11 Timer mode14 No response from IV0115 No response from IS4020 Bus access prohibited by software21 Bus data line held low23 Bus clock line held low25 Switched 5V supply missing26 CRT is not warming up in the allotted time27 Deflection failure more than three times28 IF01 guard voltage (pin 8) exceeded34 No response from the NVM chip IRO336 Wrong address passed to bus handler37 Unexpected level on NMI (power fail) line41 Bus data line not recoverable

has two TDA7269 stereo outputamplifiers (IA001 and IA002) and anMC33076 stereo amplifier (IA003)that powers the headphone socket.The board has phono output socketsfor left and right channels, subwooferand surround channels. IRO1 and atwo -level converter transistor circuit(TA021 and TA02) control the audiomute function. To prevent

overloading, the 33V supply ismonitored by a current -sensingresistor (RA080) and a switchingtransistor (TA080). When a faultcondition is detected, the switchingtransistor triggers a latch circuit thatconsists of two transistors (TA072and TA077). This mutes both poweramplifiers via steering diodes DA074and DA075.

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DTT channel revisionsIn my letter on possible interference fromdigital terrestrial TV transmissions in theFebruary 1999 issue of Television Imentioned the likelihood that DTT fromSutton Coldfield would interfere withanalogue TV reception from Emley Moor,and vice versa. This did become aproblem. We don't do much business inNorth Derbyshire, but have had a fewcustomers out that way with snowyanalogue reception caused by DTTinterference. I'd be interested in anycomments from readers who trade in theEmley Moor/Sutton Coldfield overlapareas.

That channel clash turned out to be oneof many. Four of the Chesterfield DTTmultiplexes are co -channel with EmleyMoor DTT, and problems arose as soon asChesterfield DTT transmissions started.This channel allocation was the talk of thetrade in South Yorkshire for some time,and I believe that representations weremade to the ITC about it. The recent ITCpublication Note for Applicants onCoverage for Digital Television (April 25,2002) includes a proposal to change theChesterfield channels, the main reasonbeing to remove the "co -channelrelationship between Chesterfield DTT

Send letters to "Television", Highbury Business Communications,Anne Boleyn House, 9-13 Ewell Road, Cheam, Surrey SM3 8BZor e-mail [email protected] subject heading 'Television Letters'.

Please send plain text messages. Do NOT send attachments. Be sure to type your fullname, address, postcode, telephone and e-mail address (if any).Your address and telephone number will not be published but your e-mail address willunless you state otherwise.

Please send ONLY text intended for the letters page. Correspondence relating tosubscriptions and other matters must be sent to the office address given above.

and Emley Moor DTT". It's good that theITC is trying to get it right this time.

I think everyone accepts that DTTcoverage will have to be increasedconsiderably if digital TV is to be asuccess. The only question is how to dothis. Some of the ITC's new proposals areradical, involving a number of analoguetransmitter channel changes to achieveone DTT improvement. There seems to bea shift to providing improved digital TVcoverage to the detriment of analoguereception. I suppose we have to acceptthis, as DTT is the only way forward, andyou can't make an omelette withoutbreaking eggs. To implement a six -multiplex DTT network in parallel withthe existing five -channel analoguenetwork must be fiendishly complicated.But, even so, let's hope that there aren'ttoo many mistakes this time. The ITCacknowledges the downside of many ofits new proposals, but does seem to havemissed a few possible problems.

Changes at The Wrekin would involvea move at the Derby regional relaytransmitter from channel 30 to channel28. I'm sure that if this happens BelmontBBC2 would interfere with receptionfrom the low -powered Derby relay.

Sheffield DTT channel -changeproposals involve a move at theWincobank analogue relay transmitter tochannels 54, 58, 61 and 64. Thesechannels are used for analoguetransmissions from Waltham however. Itso happens that a large part of theWincobank reception area is high up on asouth -facing slope, with a very good viewin the direction of Waltham. This is one

Red P1 and no RC operationIn the August issue Bob Flynn mentioned a problem with the Ferguson ModelC51F (ICC6 chassis) -a red P1 at the left of the picture and no remote -controloperation. I would like to add that the same situation occurs with the ICC7,ICC8, ICC9, ICC10, ICC17, ICC19, IKC2, TX91 and TX92 chassis.Vincent,Hammonds Ltd. (Gibraltar).

of the few places in South Yorkshirewhere Waltham delivers a significantsignal level. Wincobank transmits lessthan 2W ERP and the field strength, evenin the primary service area, is low. I don'tneed to say more, do I? This is the sort ofthing that a computer prediction ofcoverage and interference levels mightnot identify because the area in question,although a significant part of theWincobank target area, is very small. Isuppose that, in the ITC's grand plan,reception at a few streets in Wincobank isnot that important. But I wonder howmany other small, and some not so small,problems will arise as the newtransmission plans roll out?

Although the broadcasters andplanners have a long history of ignoringgrassroots technical information, readersmight think it worthwhile taking a lookthrough the ITC document and use theirlocal knowledge to identify and point outpotential problems. Who knows, if we actquickly enough we might end up with areasonably bug -free DTT transmissionplan. Let's hope so, because it will bewith us for a long time!

The ITC proposals make fascinatingreading, and can be downloaded from:

http://www.itc.org.uk/uploads/ITC_Note_for_Applicants_on_Coverage_for_Digital_Television.doc.The channel changes are in tabular format:http://members.lycos.co.uk/ukdtttx/change_tx.htmBill Wright,Rotherham, S. Yorkshire.Wrightsaerials@ aol.com

Faulty scan coilsOther readers may well have had the faultI've experienced with the Matsui Model1409R. Several weeks ago I was called toone that was dead, with a squeal comingfrom the line output stage. A quick checkshowed that the line output transistor wasshort-circuit. I fitted a replacement then,not being able to find any other shorts orany dry -joints, I switched on.

The new transistor went short-circuitalmost immediately, but not before I saw


a flash and a puff of smoke from the scancoils. As the coils were not bonded to theCRT, I removed them and could see quiteclearly where the damage was. I phonedCPC to try to get a price for a set of coilsand was told that the coils are availableonly with the CRT, the price being £120plus VAT!

I would normally assume that this wasan exceptional case of very bad luck forthe customer. But last week I receivedanother call to a dead Matsui 1409R: thecircumstances were the same as before,with the damage to the scan coils inexactly the same place. The number offaulty scan coils I've come across duringover thirty years in this trade can becounted on the fingers of one hand, sothere does seem to be a manufacturingproblem here. Of even more concern isthe fact that both sets were only aboutfifteen months old.

Surely, if this is going to be a regularfault with these sets, the manufacturershould make the coils available separatelyat a reduced price?Matthew Biddlecombe,West Wight Vision,Shorwell, Isle of Wight.

Fuse problemThe Matsui 1091 mains/battery portablehas a well -hidden and poor -qualityfuseholder that lives in a very warm areabeside the line output transformer. Untilnow it has been easy to get a dead setgoing by removing the 4A fuse,retensioning the holder then refitting thefuse. As these sets age however thissimple repair is not good enough.

I spent literally hours with one of thesesets checking every part I could think ofto try to get it to start up. All thecomponents I tested read, and indeedwere, good. In the end I triple checked the4A fuse. In standby there was a differenceof about a volt between one end and theother. I removed the fuse, retensioned theholder and cleaned it. When the fuse wasrefitted the set still refused to start up andthere was still the 1V difference. Indesperation, I soldered a bit of fusewire(not a nail!) across the fuse. The set thenstarted up first time. Once the fuse andholder had been replaced the set was OK.I can only conclude that the set needs ahuge 'gulp' of power to start up, and thefuseholder was acting as a resistor. For alasting repair a replacement is necessary.

The same basic chassis is used in theAlba/Bush CTV100. The fuse concernedis in the DC feed to the 11V seriesregulator circuit. There's a separate ACmains fuse.Robert Philpot,Haywards Heath, W. Sussex.

Tripler constructionAs part of a project to refurbish aprofessional widescreen TV (not PC)monitor, I'm about to try to make my owntripler - as a replacement for a failed unitfor which I can find no source of supply.Making a tripler myself has theadvantages that I have control over thedesign and physical form.

I will use six BY8416 diodes and five1,000pF, 15kV capacitors, with fifteenseries -connected high -voltage resistors tobleed 100µA from the 28kV EHT - this

provides feedback to the control stages ofthe EHT generator, which is separatefrom the line output stage. A solid -carbon4.7k52, 2W resistor in series with theoutput will provide surge limiting. I'll useflying leads for the chassis, the focus -voltage tap, EHT and bleed currentconnections, and a pin to take the wirefrom the EHT transformer. The diodesand resistors will be strung between acouple of polypropylene strips, with thecapacitors on the outsides, and the wholelot will be encapsulated in a small ABSpotting box using epoxy resin. Theprofessionals apparently "pull a vacuum"to eliminate air, but I'm told that heatingthe resin to 50°C and pouring it gentlyinto the lowest corner of the box (with thejig tilted at first) should suffice as a DIYalternative.

Has anyone else tried doing this? I'mnot sure what my chances are ofproducing in this way a tripler that worksproperly and reliably, but thought I'd giveit a go. Incidentally I've experimentedwith an unpotted doubler that could bedriven to provide about 18kV before thesparks and bangs made it clear whyencapsulation is needed! My e-mailaddress is [email protected] Burgess,2 New Coppice, St. Johns,Woking, Surrey GU21 8US.

Pioneer laser lensesIn the September issue Robin Beaumontmentioned the problem of detachedPioneer laser lenses. I've come across thisproblem on many occasions over theyears, and have never found it necessary

CORRECTIONSThere were several errors in the article on the Sony FE -1 chassislast month. The circuits shown in Figs. 1 and 3 have lots of littlesquares on them, in the lettering. They certainly aren't there onthe editorial computer screens! What has happened is that everyreturn used by our draughtsman in producing the lettering with hisPC has led either the Highbury server computer or the computer atthe printer's end to produce a square. We are trying to establishwhy this occurred.

Unfortunately the printers used the same artwork for Figs. 2and 4, which were scanned in. Fig. 2 should show volume + notvolume -, see Fig. 1 below. Fig. 4 is correct as printed.

The rather strange network shown in Fig. 2 below was omittedfrom Fig. 3. John's fault this time. Between pin 2 of IC606 (thesource connection for the integrated MOSFET chopper transistor)and resistors R659/660 there's a diode short-circuited by a leadwith two ferrite beads. Frankly, I didn't believe it - especially asthe Sony circuit diagram shows pin 3 of IC606 connected to chas-sis! Apparently the diode is there "to reduce the reverse voltagefor the MOSFET", while the ferrite beads "reduce noise from thepower supply". I still don't believe it!

The e.mail address for Bobby Doorwanand given in the Augustissue (page 633) was incorrect. It should have [email protected]

The computer compatibility problem mentioned earlier (those lit-tle squares) is presumably the cause of another weirdo. Severalminus signs in circuit diagrams have appeared as an n with a tilde

+I

(ON SCREENDISPLAY)

Fig. 1: How to enter the service mode, Sony FE -1 chassis.Press the keys shown while the set is in standby.

on*IN* 5(DIGIT 5)

above. Examples are Figs. 1 and 2on page 589 in the August issueand Fig. 2 on page 527 of the Julyissue. We are trying to establishthe cause of this.

We have been asked about thelast line (omitted) of the leader inthe June issue (page 451). Itshould have read "faces an uncer-tain future".

Well, one or two human fail-ures, one or two computer ones.Computers aren't new, so why arewe still experiencing trouble? Theanswer seems to be different ver-sions of software that lack com-patibility in some respects. Anyoneknow why my PC's insert key nolonger works after some new soft-ware was installed (bog standard Windows Word)? It's a realpain. J.A.R.

(VOLUME +) (TV)

Fig. 2: items connected topin 2 of IC606 in the SonyFE -1 chassis.


to replace the laser. As Robin says, themissing lens is often to be found rollingaround in the bottom of the unit. It willneed a good clean inside and out beforeproceeding.

The manufacturer uses several blobs ofa tacky, stretchy adhesive, similar toEvoStick impact adhesive, to secure thelens. This type of glue is easily brokendown by cleaners such as alcohol. Ifowners use wet -type cleaning discs, thismay be the reason why the lenses fall out.It's essential that the old glue iscompletely removed from both the lensand the carrier on the focus/trackingmotor. If this is not done, the lens will notsit flat in the carrier and the trackingmotor/servo may not have sufficient rangeto pull it back in parallel with the disc. Toremove the old glue I start by using afine -tipped scalpel to get the bulk of it offthe lens rim and the carrier. I finish offwith alcohol on a cotton bud, then use apowerful magnifier to examine both ofthese items to ensure that all traces of theoriginal glue have truly gone.

Reposition the lens in the carrier. Thenuse scalpel tips to push down firmly onopposite edges of the rim. Check with the

magnifier to ensure that the lens isabsolutely flush with the face of thecarrier. Once you are satisfied that thelens is positioned as perfectly as possibleit can be reglued, using super glue appliedon the end of a needle. Put four tiny blobsaround the periphery of the lens: beingquite a fine liquid, it quickly gets into theminute gap between the lens and thecarrier, and rapidly cures to provide apermanent bond.

Then go through the set-up procedure.The laser power can be checked bylooking for a 1-1.2V peak -to -peak eyepattern at TP1, adjusting the tinypotentiometer on the laser flexiprint asnecessary (unlike most manufacturers'lenses, this is a valid set-up parameter forPioneer lenses). Finally, check and set thefocus and tracking offsets, then the servogains.

This might sound like an involvedprocedure but, in my opinion, it's farpreferable to the high cost of a new laserunit for these models and the very trickyprocedure for diffraction gratingadjustment with a replacement unit.

In cases where the lens has been lostthrough one of the ventilation slots in the

case, I have successfully replaced it with alens from a scrap laser unit of differentmanufacture. You can even use a lensfrom a Sony KSS series pickup. Therewill doubtless be screams of horror fromthose knowledgeable in optical matters,but all I've ever found it necessary to dois to reset the focus offset, presumably tocompensate for a slightly different focallength. Any replacement lens is usually atight enough fit in the carrier to remain inplace temporarily. This enables differentlenses from different scrap lasers to betried. Lenses are easily removed by gentleprying around their edges with a curved -blade scalpel.Geoff Darby, Monitech,Earls Barton, Northampton.

Telephone checksWhen I tried the phone number given inthe letter with the above heading in theSeptember issue it didn't work. Thenumber I use, which seems to workanywhere, is 17070. There are voiceprompts for different tests.Allan Snow,Tewkesbury,Gloucestershire.

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DX andSatelliteReceptioTerrestrial DX and satellite TV receptionreports. News on international TV broad-casting and satellite band changes. Anunusual interference problem. More onmoon -bounce reception. A low-cost satellitespectrum monitor. Roger Bunney reports

A live report from the Los Angeles FBI chief on the airportshooting, received via NSS-7 at 21.5°W.

If a TV-DXer won the lottery he would be well advised toconsider retiring to Cyprus. It seems to me to be the ideallocation. During June Cyril Willis headed there for a week's

break, with appropriate DXing equipment of course. Jordan chs.E3, E9 and El 1 and Syria ch. E3 are received daily, and Band IIIis full of Arabic stations. A number of local Greek, Turkish andFrench -language stations are available (the latter on chs. E7 andE8). And of course there are blue skies and sea, a change from theUK!

Sporadic E reception was reasonable during early July, but thesignals gradually dropped away as the month progressed. At leastTVE was still transmitting across Band I on July 28: the latestdate announced for closure of the service has been the 31st.Here's the SpE log for the month:

im02 LRT (Latvia) ch. R2; PTP (Russia) R2; ETV(Estonia) R2; SVT (Sweden) ch. E4.

2/7/02 RTP (Portugal) E2, 3; TVE (Spain) E2-4.3/7/02 TVE E2-4; RTP E2, 3; RAI (Italy) IA, B; Tele-A

(Italy) E2-; TVA (Italy) E3-; RTL Klub (Hungary)R2; BTV (Belarus) R2; C+ (France) L2; HRT(Croatia) E4; TIN (Jordan) E3 at 0955 BST thenFrench -language programming until 1000 hours.

4/7/02 TVE E2-4; RTP E2, 3; RAI IA; Tele-A E2-; anunidentified Arabic signal at 0909 hours.

5/7/02 TVE E2-3; RAI IA, B; SVT E2-4; NRK (Norway)E2-4; YLE (Finland) E4.

6/7/02 TVE E2, 3; RAI IA; C+ L2, 3; Tele-A E2-.7/7/02 TVE E2-4; RTP E3.8/7/02 RAI IA; SVT E2, 3; NRK E2, 3; BTV R1; LRT R2.9/7/02 LRT E2; TVE E2, 3.

10/7/02 RAI IA, B; C+ L2;Tele-A E-.12/7/02 NRK E2-4; RAI IA, B; LRT R2.14/7/02 RAI IA; TVE E3.15/7/02 RTP E2, 3; TVE E3; NRK E2, 3.16/7/02 SVT E2, 4; YLE E3, 4; BTV R2; PTP R2.18/7/02 NRK E2-4; YLE E3.19/7/02 NRK E2.24/7/02 TVE E2, 3.26/7/02 RAI IA.28/7/02 TVE E2-4; RAI IA.

Analogue TV in Band I is still alive and reasonably well.Signals received during the 2002 Sporadic E season had an oddpropagation characteristic: they were of short duration, rising togood levels then fading out within a few minutes. There werecertainly fewer SpE openings that lasted for several hours.Reception was generally along a north -south path, fromScandinavia down to Italy and the Iberian peninsula. No twosuccessive SpE seasons are ever the same!

Satellite sightingsSummertime means more sports activity, which is usuallyreflected in the satellite feeds. I missed the Tour de Francecycling event this time. Over the years the French have honedtheir coverage of the race, achieving real excellence, forexample live air shots of the cyclists speeding round mountainpasses and shots from the backs of motorcycles. But EdmundSpicer (Littlehampton) found the French cycles at Telecom 2A(3°E), in a four -channel package at 12.606GHz V (SR 27,500,FEC 3/4). The four channels were provided by differentcameras, with the service identifications GCR/PGM/RMX,GCR/PGM2, PGM3 and PGM4. The first three were land -based,the fourth being the helicopter camera - with sound effects (left)but no audio commentary. Interesting that a BBC SNG truckwas seen using 2A, identified as BBC UKI-365 P2, at12.522GHz V (27,500, 3/4) with a live transmission from AlbertSquare, Manchester for BBC news at 1300 hours. This was anitem about the 10CC group. It might have been a good slot tocheck for OB downlinks during the Commonwealth Games.


NSS-7 has now replaced NSS K at 21.5°W. On July 25 fromabout 2100 UK time it was relaying, via both Reuters feeds(11.462GHz and 11.487GHz V, SR 5,632, FEC 3/4), a veryprotracted opening ceremony for the Canadian Youth Gameswith the Pope present. There were lots of flags and marchingathletes. The Pope made a speech and acknowledged the athleteswho were presented to him.

On the 20th I found BT's TES -34 truck relaying via Intelsat801 (31.5°W) from a venue outside Leeds Football club. Thelive report, at 10.956GHz V (5,632, 3/4), was for Sky SportsNews. Edmond Spiar reports frequent TES -34 downlinking via801 at 10.960GHz V (5,632, 3/4) with colour bars plusidentification. I checked this frequency at 1500 on the 27th andfound a signal that was trying but failing to lock. I'm beginningto suspect a problem somewhere in my system and will bereplacing the LNB shortly!

Roy Carman (Dorking) alerted me to the fact that Fox NewsKabul via Europe*Star-1 (45°E) has moved from 11.675GHz to11.553GHz V, with changed parameters (SR 5,470 and FEC3/4). This NTSC feed is fired up on most evenings, with colourbars and identifications or actual reports for US networks. Withwar battles over, it's the only active link via this satellite. But itpays to be alert. While checking Europe*Star-1 at 1830 hours onthe 16th I came across Globecast Africa -2 with a significantnews item from APTN's Johannesburg bureau. Pictures showeda Kuwaiti minister or official being shown around an arms site,viewing guns, tanks, aircraft etc. The picture cut to a large roomin which a presentation was being given, showing pictures ofmilitary hardware with "this is what we will be using when wego into Iraq" clearly stated. Globecast Africa -2 can be found atat 11.512GHz V (5,632, 3/4).

Just after the last column was sent in there was theunfortunate wedding -party bombing incident in Afghanistan.This led to a number of reports. I found BBC UKI-302 Bagramat 11.661GHz, BBC UKI-579 via Taridan Scopus at 11.553GHzand the Fox News outfit using its old frequency, 11.675GHz.These feeds all used 5,632, 3/4.

At 1800 hours on the 20th I found Meridian 8mbit TES -9feeding air display action to Meridian Tonight. This was via 801at 10.974GHz V (5,632, 3/4).

From about 2230 hours on July 4 live action at Los Angelesairport was seen. An Egyptian gunman had fired on people nearthe El Al flight booking desk, hitting several before he wasforced to the floor and shot by an El Al security official. Thereport was carried by NSS-7 at 11.462GHz V and took overmuch of the output of the local TV channel KNBC-4, includingseveral live interviews. Pictures included the dead and injuredbeing carried away, helicopter shots and the general confusion aslive news broke. There were statements to the press by the localhead of the FBI, the mayor, the fire chief and the police chief.Pictures were also appearing from a crash site some 35 miles tothe north of LA, where a light plane had crashed into a lakesiderecreation area. Not a very good July 4 Independence day forCalifornia.

Hugh Cocks (Algarve, Portugal) mentions that Canal Plus isstill present in analogue form from Telecom/Atlantic Bird -2(8°W), at 12.606GHz V. The Turkish TRT1/2/3/4 services areavailable in FTA form from Eutelsat W3 (7°E) at 11.429GHz V.The same satellite carries Turkish CNN in FTA form at11.534GHz V. These digital signals have an SR of 30,000 andFEC 3/4.

I had a tip that Israeli TV is being transmitted in FTA form viaHot Bird and found it at 11.216GHz H (6,159, 3/4). There's achannel multiplex as follows. Arirang-TV, a Korean channel withEnglish subtitles: this is a 24 -hour channel for Koreans overseas.Channel 3 -Arabic IBA -TV is an Israeli TV channel with Arabicsound and Hebrew subtitles. BK-TV 063 SAT is a TV channeluplinked from the Balkans. There are also three radio channels,Swiss Music Radio, Radio Greece and R.R. Radio 3. An unusualpackage! PIDS are: APID 3106, VPID 3105, PCR 3105.

REUTERS

THE WAS EUROPEAN SERVICE IS NOW

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REUTERS 40 Help Desk +44 20 7542 224k

Changes to NSS-7 downlink frequencies.

Broadcast newsChina: A digital TV service in Shanghai will enable buspassengers to view programmes during their journeys. It's atpresent being tested. Tests are also being carried out in Shenzhenand Beijing. On July 1 China Central TV (CCTV) launched itsEnglish -language service CCTV -9 on the main Hong Kong cablesystem.Afghanistan: Two European satellite TV operators are providing

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$10m to help rebuild the TV service, which has only just returnedto air. TV production/engineering expertise will be provided,along with equipment, to get Kabul TV and its relays back inoperation.

Switzerland: A gradual closedown of the Swiss TV analogueservices has started, with only the main local language beingtransmitted in each area. It has been the practice for differentlanguages to be transmitted - Swiss TV transmits in French(TSR1, 2), German (SF1, 2) and Italian (TS I, 2). Once the DTTsystem is up and running there will be a resumption of triple -language services across the country.

Indonesia: The new communications and information ministerhas announced restrictions on the expansion of private radio/TVbroadcasting, which will be retained primarily as local or regionalservices. The only national broadcasting networks will be thestate-owned TVRI (TV) and RRI (radio) services.

Farewell TV 12The ITC decided not to renew the Isle of Wight TV station TV12's four-year RSL licence, which has instead been awarded toSolent TV, an offshoot of Island Volunteers, a non-profitcharitable group. TV 12 had maintained a seven -hour weekdayservice, with more hours at the weekends, using locally -producedand bought -in material and repeats, interspersed withcommercials, and was probably the longest -running RSL-TVservice. It wasn't exactly riveting viewing, but did offerinteresting alternatives - such as live Cowes Week yachting.Future TV 12 plans had included expansion to Chichester in WestSussex.

Solent TV will offer "localness and community involvement . .

. exploiting links with local news, training and educationproviders". The announcement was made on July 19. TV 12reacted by hitting the off button, and soon after ch. 54 went dark.

Satellite newsAn S -band satellite service, AirTV, is to provide the BBC World24 -hour news channel and other TV programming for passengeraircraft while in flight. The global service will be transmitted fromfour geostationary satellites, along with internet, e-mail and otherdata services.

NEP/MPS NB

F M BALTIMORE

ILICO A _ URSE111.1M- BALTIMORE, MARYLAND

A day at the races: goodnight from the Pimlico Race Course,Baltimore, Maryland.

The Iraq government is to allow selected satellite TV channelsto be received. Initially viewers in Baghdad will be able to receivethe approved satellite programming as a terrestrial pay -TVservice, which will be encoded and require a subscription card. Inthe next phase of expansion the service will be extended toNinawa and Basra.

BBC World has upset the Chinese government, which has cutthe uplink to Sinosat-1. The BBC had screened an item aboutthe Falun Gong spiritual movement.

The European service provided by the Chinese Phoenixchannel is to start 24 -hour operation shortly - it's been on -air inEurope for over ten years. Additional programming will beobtained from Hong. Kong and North American Chinese TVchannels.

The Czech channel TV3 has gone blank following an end tofunding by European Media Ventures.

Finally a correction. In the August column, page 612, I saidthat James Murdoch, chairman of the Hong Kong based Start TV,is no relation of Rupert. In fact he is Rupert's youngest son.

CCTV interferenceThe following account of an unusual interference problem is basedon a report by columnist Lawrence Harris, who writes a monthlyarticle in Short Wave Magazine on weather satellites (NOAA,Meteosat etc.). One of his contacts, Kevin Hughes (Tamworth),had been suffering from interference during NOAA-14 passes(reception at 137.620MHz), the symptom being wavy lines onreceived images. His 'turnstile' aerial - crossed dipoles andreflectors - was checked and found to be OK, there were noproblems with his domestic mains -powered equipment, and themains input was monitored and found to be clean. Kevin decidedto contact the Radiocommunications Agency and, as he isregistered with NOAA for downlink image reception and the137MHz weather satellite band is a protected service, the Agencyswung into action.

Agency investigators disconnected the mains supply to Kevin'shouse, then used an external generator to power specific items ofequipment. All were found to be clean, but an off -air interferencesignal at about 137MHz was noticed. The investigatorsdisappeared to trace its source.

Meanwhile Kevin checked with his Icom PCR1000 'computerradio' and found that the rogue signal was at 137.640MHz. Theinvestigators were informed. They reappeared and confirmed thata signal was indeed present at this frequency - the PCR1000performed rather better than the Agency's Racal and Rhode andSchwarz equipment. Directional aerials were then used todetermine the bearing of the interference, which was eventuallyfound to be caused by a fault in a CCTV system at a largeSafeway's distribution depot some 4km away. Once the defectiveitem had been replaced, the wavy lines disappeared.

Moon -bounce receptionLast month I mentioned experiments on moon -bounce receptioncarried out by Anthony Mann in Australia. He has now sentfurther information, via Hugh Cocks. His recent experiments hadexploited the possibilities with very narrow audio bandwidths,down to 2Hz. However a US radio amateur (K3PGP) in NewJersey had, back 1972-5, successfully received two ch. A68transmitters via this propagation mode, using a 24ft, 0.6f/d dishand a ch. A68 feed. This channel was selected because no nearbytransmitters used the frequency. The two stations received were inNew Jersey and California. Pointing a high -gain aerial in thedirection of the New Jersey transmitter confirmed that directreception was not possible at K3PGP's location.

As the moon appeared over the horizon, EME signals werereceived from the New Jersey transmitter. They faded out as themoon rose higher. Further confirmation was provided by theDoppler shift in signal frequency. About three hours later, as the


moon rose over California, a video carrier plus 15.750kHz (linefrequency) sidebands was received. When this was fed to a videomonitor a distorted picture consisting of sync bars was resolved.The bars appeared wider than normal, perhaps because of thespherical shape of the moon's reflective surface. The 4.5MHzsound carrier produced distorted FM audio.

Further thoughts on this reception were contained in another e-mail from Australia. The moon's rough surface will smearreflected video signals, 'widening' the sync pulses and makingdetection easier because of the better integration time. Multi -pathphase shifts would make FM video harder to receive than AM,with a 2dB rise from sync to blanking and another 6dB for lockedsync and basic video image recognition. Amateur TV experimentswith a narrow IF bandwidth, say 0.1MHz, would allow very largecall -sign letters to be resolved, but for broadcast TV signals withtheir wide bandwidth much higher -gain reception systems areneeded.

Hugh, in the Algarve, is experimenting with a 2.4m dish, ahelical UHF feed to a Labgear head amplifier with a 1.8dB noisefigure, and a scanner. The saga continues, and any successes willbe reported.

Low-cost satellite spectrum monitorThe June 2002 issue of the NZ publication SatFACTS containeda review of a low-cost satellite spectrum monitor that'ssimplicity itself to use. The signal path from a Ku- or C -bandLNB is to a satellite receiver (analogue or digital) then thespectrum monitor box, whose video output is connected to amonitor or TV set. The spectrum monitor box contains an L -band (satellite IF) tuner and a ramp generator that's used tosweep across the IF spectrum. Any signals found appear asspikes at the left-hand side of the screen, see Fig. 1.

This is not a complex, accurately -calibrated test instrument.It's simply used to show any/all activity from a given satellite

Test Case 478Cathode Ray has been going through a bad patch recently.There had been the CD player for which he had ordered anexpensive laser unit, only to find that it didn't cure the problem;the Sony fiasco, when he had blown up a 100 -pin processorchip because he forgot to replace his earthing wristband after avisit to the toilet; and the disgraceful business of the Coca-Colaspilt into a customer's music centre while he was re-enactingone of England's goals in the World Cup.

We now find him, determined to do better, trying hard tolocate the cause of a fault with a thirteen -year old VCR. Why ishe doing this? Well, it belongs to old Cynthia Dukes, who justabout understands the machine but could never get to grips witha different model! Her son is willing to go to £50, as long asthere's a reasonable assurance that the VCR will last a whilelonger. It's an Hitachi VTM622, and the problem is easy todescribe: failure to record new sound, and audio from theprevious recording left on the tape. There were also floatingpatterns of woolly colour when the faulty recordings wereplayed back. Clearly the audio bias/erase oscillator had stopped.Ray checked the connections to the full -erase head on the deck.They were OK, so he got out the service manual and turned topage 5-11, the audio circuit diagram.

He found that the circuitry is very simple. It mainly consistsof IC401 (LA7295), which looks after all the audio record andplayback functions. Since playback of a known good tape wasOK, Ray concentrated on the record circuit. The closer he got tothe chip, the more he became conscious of a horrible smell! It

Fig. 1: The display produced by the Spectralook satellite spectrummonitor.

once this has been found and a polarisation has been selected. Itstrikes me as being an ideal tuning/search aid to enable sat -zappers to check for satellite downlink signals. The unit is madein Sweden by Emitor and is known in Europe as theSpectralook. Down under it's distributed by AV -Comm PtyLtd., Australia. I am trying to obtain a unit to try out and hopeto report back on it.

was coming from the 12V supply's decoupling capacitor C413(33µF, 16V), which had black legs and was oozing electrolyte.But a replacement had no effect at all on the fault symptom.

At this point Ray discovered that the machine's E -E sound,monitored by the TV set, became low in volume, distorted andsuffused with a squealing sound whenever the machine was putinto the record mode. Strange! An oscilloscope check showedthat the 12V supply at pin 8 of IC401 developed excessiveripple, and dropped by a volt or so, in the record mode. Moresignificant was the fact that the switched supply for thebias/erase oscillator, at pin 1 of IC401, was very low at 3-4Vinstead of the specified 11V. There was also heavy ripple here.Since one electrolytic capacitor in the circuitry had rotted, itwas a fair bet that others had deteriorated. Cathode Rayreplaced those he felt were relevant - C411, C418 and C423.But the originals must have been OK, since the fault was thereas surely as before once the replacements had been fitted.

It seemed that the cause of the fault was to do with IC401.CR found that the switched voltages from its control sectionwere present and correct: 3.6V at pin 2 during record, and OV atpin 10. Ray came to the conclusion that the IC had some sort ofinternal trouble. It certainly ran warm in the record mode. Areplacement was ordered pronto, and fitted next day. But thefault was still there!

What had Ray overlooked? Was this repair about to godownhill like those others? For the solution, turn to page 762.


SATELLITEReports fromChristopher HollandHugh CocksandMichael Dranfield

Local -oscillator settingMr James phoned to complain that ITVwas missing. He said everything else wasall right. While questioning him I askedhim to go to EPG no. 190, Hallmark. This

NOTEBOOKwas also missing, but whereas ITV pro-duced the message "no satellite signal isbeing received" Hallmark came up with"there is a technical fault with this chan-nel, please try later". As ITV andHallmark are both low -band signals, itwas certain that either the LNB or thereceiver was the cause of the trouble.

Before getting involved with the LNBon the roof, I used our signal analyser tocheck the signal coming down the cable.The LNB seemed to switch correctly fromhigh- to low -band, and between horizontaland vertical polarisation. According to ourin -line LNB voltage, current and tone

checker the digibox produced the 22kHzswitching tone for high -band operationand switched it off when ITV was select-ed. Time to look at the digibox's installa-tion menu.

Once into the installer setup menu,after pressing 0 then 1 then 'select' on theremote -control unit, I headed straight foroption 1, the LNB setup submenu. Thecause of the problem was immediatelyclear (see Photo 1): the low -band local -oscillator frequency was set at 9.8GHzinstead of 9.75GHz. The factory -defaultsettings can be obtained by pressing theremote -control unit's red button. Oncethis had been done (see Photo 2) ITV andHallmark were received normally.

Mr James swears that no one had gotinto the installation menu to alter the set-tings, but I suspect that his video gameplaying teenage son was the culprit. It'snot a good idea to use this menu to prac-tice remote -control unit skills! C.H.

Digital channel updateThe latest channel additions at 28.2°E arelisted in Table 1 - where assigned, theEPG number is shown in brackets afterthe channel name.

UK Gold 2 has been moved from EPG110 to 111 to make way for UK Gold + 1hour. The latter was testing in July with a"UK Engineering Test" caption (see Photo3) and unrelated sound and picture con-tent. Photo 4 shows the BBC Radio 1Xtralaunch caption. Casino TV has been seentesting via Eurobird transponder D5S withcolour bars and a caption, see Photo 5.The I Race channel started tests in earlyAugust via Astra transponder 13, seePhoto 6.

Teamtalk 252 radio (transponder 33,EPG 910) and Einstein TV (transponderD7S, EPG 576) have ceased transmis-sions. C.H.

C -band receptionMany services that are not usually avail-able in Europe as Ku -band transmissionscan be received in Band C (4GHz). Alarger dish is required: a 1.5m or 1.8mdish will provide good reception of a num-ber of signals. I intend to take a look at

sky 5.23pm Sat 10

guide LNB SETUP

Low Sand LO Frequency (GHt)

LNB Power Su 122 KHz Command

L. IS

INCORRECTFREQUEN

Enter frequency and press

sky 5.23prn Sat 10

guide LNB SETUP

RRECTPRESS

Enter frequency and press

Photo 1: LNB setup submenu, showing Photo 2: LNB setup submenu after local -incorrect low -band local -oscillator frequency. oscillator frequency correction.

Photo 3: UK Gold + 1 hour test captionwith unrelated picture content.


This is 1Xtra

lAta, the f(tr fa::, of 'f.:act, o.t

digital dial tumurruAr at 6.04nt. Mlle in fur the best inkree. dancehall, UK Garage, hip hop and drum andbass, 24 - 7.

1Xtra BBC §.57_pm Thu 15_

NOW !hit: is 1Xtra

Sqatch Channel' Search Fa vourite

Photo 4: The BBC Radio 1Xtra launchcaption.

WWW.DISC.TUFurther schedule information is not available

Photo 5: Casino TV test transmission viaEurobird transponder D5S.

Photo 6: An I Race channel testtransmission via transponder 13.

Photo 7: The KNR TV (Greenland) testpattern. A C -band transmission via Intelsat903 at 345°W.

Table 1: Latest digital channel changes

Channel and EPG Sat TP Frequency(GHz)/pol

BBC Radio 1Xtra (919) 2A 5 11.798/HBBC Radio Nan Gaidheal 2A 5 11.798/HBig Entertainment Network (238) EB D11S 11.662/HCasino TV (tests) EB D5S 11.546/HI Race (tests) 2A 13 11.954/HMoto Radio EB D9S 11.623/HSimply Nature (579) 2B 37 12.422/HSky Travel Extra (146) 2A 4 11.778/VStop and Shop (660) EB D5S 11.546/HUK Gold + 1 hour (110) 2A 13 11.954/HWonderful EB D9S 11.623/H

TP = transponder. 2A = Astra 2A, 28 = Astra 2B, EB = Eurobird.

various C -band satellites over the comingmonths. We'll start with Intelsat 903 at34-5°W.

This is the home of KNR TV fromGreenland and Canadian Forces TV. KNRTV is at 3.716GHz with left-hand circularpolarisation, a symbol rate of 2,716 and7/8 forward error correction. It originatesin Denmark, with programming from themain Danish networks. When programmesare not being transmitted (time three hoursbehind the UK) a test pattern is seen, seePhoto 7.

Canadian Forces TV lives just aboveKNR TV, at 3-721GHz, with right-hand cir-cular polarisation, a symbol rate of 7,898and 1/2 FEC. It's aimed at Canadian Forcesoverseas and provides a mixture of pro-grammes from Canadian TV networks. OneFrench- and one English -language TVchannel is transmitted together with fourradio stations, two in each language. TheTV signals are in 525 -line format. Mostmodern digital receivers designed to be ableto handle a low symbol rate can cope withthis and, if the TV set has an RGB input,the programmes will be seen in colour eventhough the set doesn't have an NTSCdecoder. See Photo 8. The signals are some-times scrambled, but when this happens twoof the radio stations remain in the clear.

Photo 8: A Canadian Forces TVtransmission via Intelsat 903.

Until recently and as far back as EarlyBird in the mid -Sixties the 34.5°W slotwas used for numerous news feeds andprogramme exchanges, in both PAL andNTSC form. These were at the top of theband (4.150-4-175GHz) with right-handcircular polarisation. The occasional digi-tal feed may still be found in this part ofthe band, but these signals have largelyceased - because of the multitude of othersatellites available for transatlantic links.H.C.

Panasonic TU-DSB20When this digibox came on it said it was"searching for listings". But no matter howlong you waited no listings appeared. Acheck in the services menu revealed thatthe unit was receiving a good signal, andquality and lock were OK, but there wasno network ID and no transport streamdata.

Checks at the 208 -pin ST2OTP3BX5OSchip IC421 showed that MPEG data wasentering at pins 69-76, so a front-end tuneror AD converter fault was ruled out. Thenext step was to check for digital activityat the memory address pins 1-28 andmemory data pins 30-67. They were allstuck high at 3.3V, so the bus had stopped.A replacement chip cured the fault. M.D.

Pace 2200If one of these digiboxes is stuck in stand-by, check for oscillation at the modemcrystal X700 (29.4912MHz). If the clocksignal is missing, try a replacement crystalbefore, if necessary, fitting a newDSP1675 modem chip.

Another possibility is loss of the27MHz clock signal at pin 110 of theST2OTP3 chip U300. If it's missing andthe chip is cold, check at pin 3 of thebuffer U370. If the signal is missing here,suspect failure of the 27MHz crystalX370. Be careful when replacing it, as theprint is very thin here. M.D.


MONITORSFault reports fromGerry MumfordDean RatcliffeAllan Horsfieldand Ian Field

We welcome fault reports from readers- payment for each fault is made afterpublication.

Reports can be sent by post to:

Television, Fault Reports,Anne Boleyn House,9-13 Ewell Road,Cheam,Surrey SM3 8BZ

or e -mailed to:[email protected]

Daewoo 531XThis monitor powered up with the greenLED on, but there was no display. A fewchecks revealed the cause: no line drive.The supply to the scanning processor chipwas missing because of a short across the12V line. After much hunting the culpritwas found to be decoupling capacitorC506 (330g, 16V) - which is just next tothe scanning processor chip! Areplacement restored normal operation.G.M.

Fujitsu E156 (Model P1115A)There was a dim display with thin, blackhorizontal lines across it. In addition aloud buzzing noise came from inside themonitor. Visual inspection showed that themains rectifier's reservoir capacitor C608(180g, 400V) was faulty with a bulgingtop. When tested it was virtually open -circuit. The unit happily accepted areplacement capacitor with the morereadily available value of 150KF, 400V,which cured the fault. G.M.

Taxan EV750TC095(Mitsubishi chassis)This monitor was dead, tripping loudly andblinking its LED. The 2SC5331 line outputtransistor Q503, the 2S7306 B+ regulatorFET Q504 and the 2SD1073 EW outputtransistor Q505 were all short-circuit,while the feed resistor R512 (0.820, 1Wfusible) was open -circuit. Once these itemshad been replaced the monitor powered upand worked, but when it was put on soaktest it repeatedly failed after a few hours,damaging the same components. Thecause of the trouble was eventually tracedto D503 (ERB93-02), which was slightlyleaky. It took almost as long to find asource of this Panasonic diode as it did todiagnose the fault! G.M.

Hansol 710A (Model B17CL)This monitor's display was on an over -bright, white raster with flyback linesvisible -on it. The brightness controlworked correctly, so there was obviously aproblem in the tube's first anode supply. Inthis design there's no Al control on theLOPT, adjustment being carried out in theservice mode. Fortunately the cause of thefault was simple: R711 (1MQ, 0.5W) wasopen -circuit. It forms part of a potentialdivider for the Al supply. A replacementrestored normal brightness. G.M.

Jean JD156HThe problem with this monitor wasexcessive width. The width control wasinoperative, and there was no pincushioncorrection. Checks in the line output stageshowed that the transformer's scan -drivepin was dry -jointed. The thing to do is to

check the LOPT for dry -joints and resolderas necessary. Also check the 31DF6switching type diode (3A, 600V). D.R.

Axion CF1754There was no operation because the2SC5132 line output transistor Q411 wasdefective. As this type of transistor appearsto be unobtainable at present I used a2SC4916 as the replacement. The cause ofthe failure had been a dry -joint on thedeflection plug. D.R.

Dell 1025HEThis monitor produced a very healthydischarge at switch on. When Iinvestigated I found that the EHT wasarcing across the top of the line outputtransformer. An intemet search revealedthat it's a common problem with thismodel, also the Nokia 447.

Since new transformers are ratherpricey I decided to have a go at repair.Halfords clear silicone sealant was used tocover the area affected, and this did thetrick. No more arcing, and a monitorrestored to health. In fact the hardest bitwas to get the case off! A.H.

Relisys RE1420KThis monitor's mains fuse had blown. Ifound the 2SC3460 chopper transistorshort-circuit, though no immediate causewas apparent. Its 0.510, 2W emitter -current sensing resistor was intact, but its2SC2655Y base -bias control transistorQ102 had been destroyed. The CNX82Aoptocoupler had survived. As this devicehas no optotransistor base connection,testing it requires a bit of effort. A DMMdiode check can be used for the LEDsection: the forward voltage should beabout 1V. But with no base connection thesame method can't be used for theoptotransistor section. The only way tocheck this is to drive the LED. With aLED current of 10mA, the transistorsection should pass about 2mA when fedfrom a 5V rail via a 1000 resistor.

Almost every component in this self -oscillating circuit was checked, but still nocause of the fault was evident. So thedamaged components were replaced andthe unit was powered. There was voltageat the collector of the chopper transistor,but little else happened. I decided to checkthe rectifiers on the secondary side of thecircuit. D110 and D112, type BYT56,were both badly discoloured. As I didn'thave this device in stock I fitted a pair ofUF5406s. These ran a lot cooler (judgingby the discoloration of the originals) whenthe monitor was powered again, and to myrelief everything now worked.

This chassis uses an old-style EWtransductor to width -modulate the B+


supply. It's interposed betweenD110/D112 and the relevant chopper -transformer pin, and is controlled by theDC that passes through the 'exciterwinding'.

The failure of D110 and D112 couldhave been the basic cause of the fault, butI was suspicious about the choppertransistor's fixing screw - it was barelymore than finger -tight!

There are four small electrolytics onthe primary side of the power supply.C108, C109 and C130 are all 10uF, 50Vwhile C107 is 470gF, 10:V. It's advisableto replace all four.

I didn't have 2SC3460 and 2SC2655transistors in stock and instead fitted a2SC3886A and a 2SD1207. They are bothconsiderably better than the originals.Note that while the 2SC2655 and2SD1207 have b -c -e pinouts the PCB hasan e -b -c hole layout, so the transistor'sleads have to be pre -formed. I.F.

Dell VC1OCENThese tare -bones' interlaced -only SVGAmonitors remain popular, and are usuallyeasy money - just replace the three smallelectrolytics on the primary side of thepower supply, and preferably add non -electrolytic ESR-bypass decouplers (0.11IFwill suffice). However this one producedEHT but no display. The line outputtransformer's Al preset control was faulty- its output was definitely AC.

I decided to adopt the Al supplycircuitry used in the 14in. Liteon monitor-remember the ones with the 'dummy' Alpreset on the LOPT?! But the faulty supplyhad resulted in cathode glazing from ionbombardment. So I shorted out first onethen the other 1MQ feed resistor, leavingjust the 101M, 1W fusible resistor, theRGP02-20 diode, the 4.7nF, 2kV reservoircapacitor, the 4.7MQ preset and the 2.2k52`bottom -lift' resistor trailing from thecollector of the line output transistor. Ittook five minutes of peak -rectifiedcollector voltage at the tube's Al pinbefore the cathodes decided to shake a leg!

This substitute Al supply would haveworked very nicely, but there still seemedto be internal arcing in the LOPT - thepicture flickered for a few seconds whenthe monitor was first switched on. Asearch through the salvaged LOPT binproduced a spare Vi428E transformer. TheVi428E looks identical to the VC lOCENto me. If there's a difference I've notspotted it. The LOPT' s part number is alsoidentical. Unfortunately the salvagedLOPT turned out to be short-circuit - itdoes happen, though the symptom isusually mistaken for a common power -supply fault.

A further search, this time through the

scrap chassis pile, produced a chassiscomplete with LOPT. The transformerwas OK, and with the correct A 1 supplythe tube's cathodes made a furtherunexpected recovery. It's possible that theflickering had been due to the condition ofthe CRT's cathodes rather than a fault inthe original LOFT!

While on the subject of eliminatingtroublesome electrolytics, most monitorsuse them to couple the video outputs tothe CRT's cathodes. This monitor usesluF, 100V electrolytics with 1 nF discceramic capacitors in parallel. The latterimprove the resolution considerably. Iremoved and checked the video -couplingelectrolytics and found that their ESRswere between 2-3Q, which is probably notbad for electrolytics of this type. But Idecided to use the two pairs of mountingholes in each channel to fit an 0.68uF,100V capacitor and an 0.33µF, 100Vcapacitor in parallel. This reduces the ESRto negligible proportions, and theimproved resolution is noticeable! I.F.

Supercom MultisystemsSK1428GNThis 14in. SVGA monitor looks similar tothe small Acer models externally, but notinside. The sync chip bears the numberKDS9008, while most of the other chipsare of GoldStar origin. The complaint withthis one was "smell of burning". It hadundoubtedly come from C424 and C425(both 220uF, 25V), which are in theLOFT -derived ± H -shift supplies. ThePCB track had burnt up between thecathode of D409 and pin 4 of the LOFT(assuming the collector connection to bepin 1). In addition one of the 1N4935 H -shift rectifier diodes, D407, was short-circuit. No other damage was found, andthe monitor worked normally once theburnt PCB track had been cleaned up andlinked across, and a new pair ofelectrolytics and a new 1N4935 diode hadbeen fitted.

The design of this monitor predates theuse of PWM-type B+ supply control. Ituses a pair of pnp power transistors, Q406and Q410, to switch a single regulated HTline to one of three taps on the line outputtransformer's primary winding. One tap isalways connected, via D409, to thecommoned emitters of the two transistors.The two 'boost' tappings are switched inwhen the display mode requires this. D405and D406 prevent reverse current flowinto Q406 and Q410.

Somehow this repair seemed too easy!So I decided to use the monitor for a whileafter it had been on soak test for a fewhours. Sure enough the brightness wasfluctuating - only slightly, but thecustomer was bound to complain. The

soldering on the main PCB was mostlyOK. What was hidden under the CRT -basescreening was a totally different story. Inaddition the three 1µF, 50V non -polarisedelectrolytic video -coupling capacitorsC623, C629 and C634 had well and truly`gone home'. The ESR readings of allthree were off -scale (over 752) with myhome-made meter. If you can find non -electrolytic capacitors with at leastequivalent capacitance value and voltagerating, without being too big to fit theavailable space, they will provide a visibleimprovement in resolution and contrast.Their ESR will be much lower than even atop-quality electrolytic capacitor.

Many cheap monitors have onlycascode Class A video output stages,without the complementary emitter -follower pair. This one does have thelatter, providing a very low outputimpedance to drive the CRT's cathodes.The two extra transistors were wastedwith the non -polarised electrolyticcoupling capacitors originally fitted. Theyare not wasted with the non -electrolyticcapacitors I fitted. I.F.

Elonex MN009(Philips TY619 324 008625)I acquired two of these monitors for stock.Since one had the swivel base missing, Idecided to use it for spares. The onenominated for repair had a label that said"badly out of focus". In fact there was novideo. When the setting of the first anodepreset was advanced a blank rasterappeared. In addition the horizontal shiftcontrol did nothing. I decided to tackle thefocus fault first, and found that adjustmentof the focus control did very little. So Iswapped over the chassis. A good displaywas obtained with the CRT in the othercase, but after a soak test focus was lostand the A 1 level was erratic. There was nodoubt that the first CRT was faulty: it hadprobably damaged the presets, because atransformer swap solved the problem.

When the monitor was checked throughthe scan modes it refused to sync at 600 x800 and 1,024 x 768. There are two H -frequency and two H -phase presets, justinboard from the field output heatsink andon the front of the upright subpanelrespectively. The settings of these presetshave to be 'juggled' to obtain lock on allthe specified modes without the displaybeing off to one side. After over an hour Idecided to be content with all the specifiedmodes, with 640 x 480 and 600 x 800being correct at the extremes of the H -shiftcontrol. Dirty presets are a commonproblem with this chassis. Sometimes theapplication of pressure to each in turn willreveal the culprit, but on this occasion Iwasn't so lucky! I.F.


VCR CLINICReports fromRobin BeaumontNeil Sleeman-SmithRon MitchellMartyn S. DavisIvan Levy, LCGIDave GoughDean Ratcliffe andKeith Cummins

We welcome fault reports from read-ers - payment for each fault is madeafter publication. See page 744 fordetails of where and how to sendreports.

Philips VR510/07 (Apollo 12chassis)This machine's E -E picture keptdisappearing, as if it was switching to theAV input. The clue was that there was nosound in any mode. I found that theTDA9605H audio processing chip's 9Vsupply was low, with excessive voltagedrop across the 100mA fuse F1509. WhileI was carrying out checks the fuse failedcompletely, and I was able to confirm thatthe IC was faulty. A new fuse and ICrestored normal operation. R.B.

Panasonic NVHD640B (Zmechanism)This machine would shut down at randomduring play or record. I initially triedreplacing the reel sensors, but the cause ofthe trouble was loss of take-up tension. Anew clutch assembly (part no. VXP1732)and drive gear (part no. VDG1221) wererequired. R.B.

Sharp VCM26HMThis machine's stop/eject button wasbroken and the tape couldn't be ejected.Not a real problem, but when I checkedthe Sharp website I found that amodification is available - an additionalplastic bracket that restricts the travel ofthe buttons and thus reduces thelikelihood of breakage. There are twoversions of the bracket, depending on theparticular model being repaired. R.B.

Philips 14PV200/07This combi unit was stuck in standby withno bus -line activity. The fault cansometimes be caused by a memoryproblem, but in this case the TMP93C071microcontroller chip IC7900 was faulty.Replacement is not a job for the faint-hearted: the IC has 120 pins!

The same microcontroller chip is usedin the Philips Apollo 20 VCR chassis, inwhich it can cause similar problems. R.B.

Sanyo VHR776EWe had a pig of a fault with this machine.The tape loaded, but there were nofunctions and the drum was spinning fartoo fast. IC351 and the stator motor werereplaced without curing the trouble, thecause of which turned out to be C3525(0.47µF, 50V). It's connected to pin 29 ofIC351. The capacitor read all right whenchecked with our test gear. N.S-S.

GoldStar P1341This VCR seemed to be completely dead.But when the power supply was removedthe fuse was found to be intact, and ontest all outputs were present and wereclean when checked with a scope. When

the power supply was plugged back intothe main PCB the +6V supply showedterrible noise on load. C19 (1,000µF,10V) had dried up. For improvedreliability I used a 1,000pF, 16V 105°Ctype as the replacement. This got themachine going again - all the othersupplies were clean when checked. R.M.

LG 5909This rather nice VCR was dead. Itspower supply can be removed and run,up to a point, as a separate unit. Coldchecks failed to reveal any problemswith circuit protectors or start-upresistors, but CP06 (33µF, 25V) on theprimary side of the circuit read low andwas replaced. On power -up I had, asexpected, some secondary voltages.Some of the secondary voltages willalways be present, others will beswitched by the microcontroller chip onthe main board. So, was there a fault inthe power supply or on the main board?

The clue was the voltage at pin 8 ofPP501. This is shown on the circuit as5.3V, but in fact should be nearer 6V.The reading I obtained was 5.1V. Nowthere isn't a great difference between5.3V and 5.1V, but there is between 6Vand 5.1V! This voltage is provided bytwo 1,000µF capacitors, CP12 and CP13.Both read low in value, and replacementsrestored the VCR to life. M.S.D.

JVC HRJ660This machine was brought in because ithad chewed a couple of tapes. It behaveditself on my bench however. I've foundthat with machines that use this deck themode switch and a couple of idler items,as follows, should be replaced: item 102,idler lever, part no. LP30236-002B; item89, idler arm assembly, part no. LP40114-006B; and item 106, rotary encoder, partno. QSW0554-003. It seems that the mainculprit is item 102, which occasionallysticks. M.S.D.

Sanyo VHR279EThe fault report said "tape jammed". Oninvestigation I found that the cassetteloading operation was lazy, sometimesloading and sometimes stopping half way.According to the fine men at SanyoTechnical, if the loading motor drawsmore than 30mA it should be replaced. Ihaven't discovered how to measure this,since the motor sits beneath the deck inwhat is a now standard mid -mountmechanism. A replacement motor curedthe fault however. The part no. is 645 0297014. M.S.D.

Panasonic AG5260This VCR showed error 5 in its display.


When I checked its mechanical operationI found that the tape was being acceptedand laced up but the pinch roller didn'tengage, because the plastic locating pinon the assembly had broken off. A newpinch -roller assembly and general cleanrestored normal operation. I.L.

Panasonic NVHD90There was a tape stuck in this VCR'smechanism. I had to strip the mechanismdown completely and retime it. Afterfitting a new clutch, idler and roller andcleaning the very dirty deck I found thatthere was no test signal. The cause wasdry -joints in the RF modulator. I.L.

Panasonic AG5260This VCR produced a blank screen withnormal sound. Checks showed that therewas no video at pin 28 of IC3001 and thatthe IC's supply (SW5V) at pin 6 was low- only 2.5V. The cause of this lowvoltage was Q6101, which was open -circuit. I.L.

Ferguson FV71LVA tape was jammed inside this machine.Removal of the top revealed a Toshibadeck that suffers from a common fault:

the plastic pulley at the base of thecapstan motor splits and drops off. Deckremoval confirmed my suspicions.Normal operation was restored once anew pulley had been fitted. D.G.

Akai VSG240EKWhen asked to rewind or fast -forwardthis machine would display "error" andstop. The fault can be cured by removing,stripping and cleaning the mode switch.D.G.

Samsung VIK306This machine would power up for a fewseconds then die, with no display oranything. Checks in the power supplyrevealed that, as expected, the electrolyticcapacitors were to blame. One inparticular, C35 (47011F, 16V), hadleaked. I replaced this and, as aprecaution, all the other electrolytics. Theresult was a fully -restored machine. D.G.

Panasonic NVHD660This machine sometimes displayed F3 orF4 in the display when rewind or fast -forward was selected. It might work fortwo -three days before the fault put in anappearance again. This sort of thing is

caused by a defective mode switch or adefective loading -motor coupling. D.R.

Toshiba V8568There was no E -E or playback picture.Scope checks showed that the videooutput at pin 11 of the video processorchip IV001 didn't reach the buffertransistor TV011 because RVO1 1 (1000)was open -circuit. The part no. for thisresistor is 24872101. D.R.

Sony SLV715There was no reverse operation and norewind function. The cause was R003(5.6k0) on board MD49. Its part no. is124942 611. D.R.

Hitachi VTF700EThis elderly Nicam machine had runfaultlessly for over ten years but had nowdeveloped a capstan servo fault. Theservo ran in and out of lock cyclically forthe first fifteen minutes of playback,during which time the off -tape timedisplay was permanently stalled. Thecause of the fault was C613 (47µF, 16V),which was open -circuit when cool.Recording was not affected by the fault.K.C.

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Television magazine's VCR Clinic column is aunique forum for practical servicing tips, withthe UK's leading service engineers andservicing writers contributing their observationsand recommendations month by month. But tryfinding those faults reports for the AmstradXYZ I 23 that's on your bench. Even with anindex you will be chasing through a pile ofmagazines... until now. Peter Marlow's VCRFault Finding Guide is a distillation of the mostused fault reports from II years of Televisionmagazine. Arranged by make and model theinformation is extremely easy to access, and thebook is a convenient size for the bench or tocarry with you. This will undoubtedly becomeone of the service engineer's most useful tools.Unlike other fault guides, this one is based ontop quality information from leading authorities,and genuine repair case studies. This is real -lifeservicing information, not just a compilation ofmanufacturers' manuals.

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AUDIOFAULTSReports fromGeoff DarbyJ.S. Ogilvieand Martyn S. Davis

We welcome fault reports fromreaders - payment for each fault ismade after publiation. See page744 for details of where and howto send reports.

-

Sony HCD-MD373This was one of those faults whosesymptoms make you groan. When the unitwas first taken out of standby or put back,the CD spindle motor would runbackwards at high speed for about threeseconds. If the laser unit was moved awayfrom its 'home' position manually, itdidn't attempt to return at power up.

The conditions at the sled and spindlemotor outputs from the motor drive chipIC102 seemed to be about right, butapplication of a meter probe to the spindlemotor channel input pin instigated thehigh-speed reverse -spin condition. Thispin is connected via a single resistor tothe servo and DSP chip IC101. A fewquick voltage checks around IC101showed that something was amiss: therewas just over 2V at the 5V supply pin 59.This took me back to the 5V regulatorIC911 on the main PCB. It's input wascorrect at 9.7V, but there was only 2.2Vat its output. As it wasn't hot, whichwould have indicated that it was in thecurrent-foldback condition because of anoverload, I fitted a replacement. Thisrestored the 5V supply and normaloperation of the unit. G.D.

Panasonic SA-AK18The owner of this unit complained that theon/off switch didn't work properly andthat it couldn't be turned off. When theunit was initially powered it lit up like aChristmas tree, with every light andfunction indicator, including the vacuumfluorescent display, performing a lightshow of which Pink Floyd would beproud. When the unit was switched to on,the indicators and the display settled downto what you would expect and it workednormally. When off was selected thedisplay said "goodbye" then went dark,except for some Zs (sleep mode?) andunset clock dashes. This seemed to be OK,but fifteen seconds later a relay clickedand once again the light show appeared.The unit was clearly going into a demomode, but getting it back out defeated me.

I tried every combination of buttons Icould think of, including the obviousdemo button, to no avail. Finally, infrustration, I called Panasonic Technical. Iwas told that you have to press and holdthe demo button for at least five seconds.Can't think how I failed to figure that outfor myself . . . But when this procedurewas carried out the unit went offcompletely, and stayed off when theon/off button was operated. G.D.

Technics SL-HD501This is the CD part of a multi -unit mini

system. If you get one that won't playdiscs, before doing anything else removethe disc clamp (two screws) and look tosee if the laser unit is at the far end of itstravel, i.e. at the outer edge of the disc.It's common for the laser unit to stick inthis position, the sled drive motor nothaving the power to pull it back.

I don't know why the laser unitfinishes up in this position - possibly thereason is failure to read a scratched ordirty disc. Once the deck has been takenout (four screws) it's a simple matter toremove the laser unit's PCB (three screwsand four soldered joints to the motors),then the sled motor mounting plate (twoscrews). The mechanism can now befreed. Relubricate it, then wind the sledup and down its worm by hand a fewtimes to ensure that there are no othermechanical problems. Reassemble in thereverse order. You should find that thedeck now operates normally. G.D.

Sony HCD-CP33There was an odd set of symptoms but, fora change, the cause was straightforward.About two seconds after coming out ofstandby there would be an almighty bangfrom the right -channel speaker. After thatthe channel worked normally - untilswitch -off, when the bang was repeated.

The cause was dry -joints at the right -channel output chip. Two of its pins arecalled 'mute' and 'standby'. It wasprobably the mute pin that caused thetrouble. It should hold the IC off until thesupply rails are fully established. G.D.

Aiwa NSX-V90If the drawer in this or any other musiccentre fitted with the same CDmechanism won't stay shut, replace thefive -way ribbon cable. It's available fromCPC under part no. AW84-ZG1-614.

Also check the CD turntable belt, asthis can sometimes cause problems. J.S.O.

Hitachi DA6000If this CD player blows fuses, check C706(220KF, 16V) in the power supply. It tendsto go short-circuit. J.S.O.

Aiwa LCX108This recently purchased mini hi-fi wasbrought back to us because it wascompletely dead. The mains transformer'ssecondary winding was open -circuit. It'sitem 38, part no. SA-CLD-642-010. Theredidn't seem to be any reason for thefailure, and a replacement put mattersright. Maybe this could become a stockfault? M.S.D.


Steve ReoatilJry

I 4 -

AUDI4- HI -F

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ago

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SERVICING AUDIOAND HI-FI EQUIPMENTService engineers and technicianshave come to regard this book asessential to their work. As a bench -side companion and guide it hasno equal. Its purpose is to ease andspeed up the processes of faultdiagnosis, repair and testing of allclasses of home audio equipment:receivers, amplifiers, recorders andplayback machines. The mechanicsand electronics of domestic audioare examined by Nick Beer in adown-to-earth and practical way,concentrating on what goes wrong,how to track down problems, andhow to solve them.READERSHIP: Service techniciansand engineers, audio engineers.Price UK £35.00 EUR £37.00

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We welcome fault reports fromreaders - payment for each fault ismade after publiation. See page744 for details of where and howto send reports.

FINDINGGoldStar CIT2181FGThere was a black mark on the picture,most noticeable when the aerial wasdisconnected. In addition there was slightbottom field foldover when the set wascold. It took me a while I find the cause,because I had already tested the faultycomponent with my ESR checker which

said it was OK. Eventually, when Iremoved C423 (470g, 25V), I found thatits value had fallen to 120pF. You willfind this capacitor next to the standbyrelay. M.D.

Bush WS6672This set came in because it was tripping. Ifound that the BU508SAF line outputtransistor tvas short-circuit. The cause wascapacitor CD08 (560nF, 250V) which ispart of the EW modulator arrangement. Itwas open -circuit. M.D.

Samsung C15012Z (P58SCchassis)The complaint with this set was no sound.The audio processor/output chip is IC602,type TDA1013A. There was an audioinput at pin 8, but no audio was present atpin 6, the output from the volume controlsection of the chip. A meter check at pin 7,the DC volume control input, revealed thateverything was OK here - the voltagecould be varied over the range 0-6V. Asthe IC's supply (pin 3) was correct at 18V,it seemed that the IC was faulty.

The situation was the same when a new

chip had been fitted however. I was now ata loss as to what the cause could be, sinceeven a short-circuit at pin 5 (input to theoutput section of the IC) would producesome audio output at pin 6. I resorted tocold checks on the IC's peripheralcomponents, and eventually found thecause of the problem: R617 (2201(0) wasopen -circuit. It's connected between pins 3and 4. Strange, because this is part of theaudio output section of the IC. Anyway areplacement resistor cured the fault. M.D.

Philips 17PT166A(Anubis A -AC chassis)This set was in the shutdown mode, with adead short reading between the collectorand emitter of the line output transistor.The cause is usually a winding -to -earthshort in the LOPT, but not this time. Theculprit was the scan -coupling capacitorC2450 (330nF, 250V). M.D.

Sony KVX2172U (AE2Achassis)This set had very low, distorted sound. Thebar moved up and down when the volumecontrol was operated but the audio leveldidn't change. The mute button workedhowever. When a signal was fed in via thescart socket the picture would change butthe low, distorted off -air sound remained.At this stage it was clear that repair wouldbe impossible without a service manual.

Armed with this, I found that the digitalvolume control/switching chip IC201(TDA6622-5) had off -air sound going in atpins 1 (left) and 3 (right) and scart soundgoing in at pins 7 (left) and 8 (right). Butvery little audio was present at the outputpins 16 (left) and 15 (right). The correct12V was present at the power supply pin21, so it seemed that the IC must be faulty.A replacement cured the fault. M.D.

Mitsubishi CT21M1TX (Euro 10chassis)For a funny sideways picture wobble,replace C905 (470g) and C906 (47µF)which are on the primary side of thechopper power supply. M.D.

Sony KV32FQ75U (AE5Achassis)These are horrible sets to service. Thedead set symptom is not uncommon. Ifyou find that IC6604 in the power supplyis short-circuit you will also find that the0.10 safety resistor R6666 is open -circuit.Don't just replace these two items andswitch on, as they will blow immediately.Check the FET Q6806 which will be short-circuit source -to -drain. I learnt this thehard way! The part nos. are IC6604 8-729-045-40, R6666 1-202-933-61 and Q68068-729-047-59. P.S.

( October 2002 TELEVISION

Bush 2571NTX (11AK19chassis)Field collapse was the trouble here. Fromexperience of these sets, the procedure isto check whether the 100Q safety resistorR704 is open -circuit. If so the TDA8351field output chip IC701 is short-circuit.This time R704 was OK, but the 15Vsupply at pin 3 of IC701 was missing. It'sderived from pin 6 of the line outputtransformer, via the rectifier circuit D606(BA157)/C632 (1,000µF, 25V). D606was open -circuit. Once a replacement hadbeen fitted the set worked normally. P.S.

Toshiba 21504111Dead set with the red LED blinking is afault you get with this model. The 630mAfuse FD802 is open -circuit because ofshorted turns in the line outputtransformer T444 (part no. AZ363004).P.S.

Bush 216ONTX (GrundigG1000 chassis)There was sound but only a bright rasterwith this set. It didn't take long to discoverthat there was no HT supply to the CRTbase panel. Tracing back to source, Ifound that R315 (10Q) was open -circuit.It's connected to pin 9 of the LOFT. P.S.

Beko 25411NDAnother set with sound and a brightraster. The picture could be restored byturning down the setting of either thefocus or the A 1 control on the LOPT. Thecontrols worked normally when the CRTbase was removed, proving that the tubeitself was the cause of the fault. The tube,type A59EM253X07, was sent away forrebuilding. This proved to be the answer,though at some cost. P.S.

Bush 2872NTX(11AK19-E3 chassis)Here's a new problem we are getting withthis model. The symptom is a dead set,and you find that the 0.22Q resistor R870in the power supply is open -circuit. Thecause is C833 arcing against the choppertransistor's heatsink. R870 and C833 areconnected in series. P.S.

Toshiba 50WH18BIt seems that stuck in standby is becominga common fault with this projection set.The cheapest and easiest solution is toreplace the text panel, part no. 23786696,which can be obtained at £21.70 plusVAT. P.S.

Sharp 66CS-03H (CS chassis)This chassis can be a headache. Fieldcramp at the top of the screen, improvingas the set warms up, is a known fault

however. The cause is C512 (22µF, 50V).P.S.

Bush BTV17I've had several of these sets, and theMatsui versions, that were stuck instandby. A modification kit, part no.BTV17MODKIT, that consists of a smallplug-in PCB with full instructions, usuallyrestores normal working order. But Iwould recommend obtaining a servicemanual and thoroughly checking that allthe option bytes are set correctly beforethe set is returned to the customer. P.L.

Toshiba 140ORBT/140ORBWThe picture had gradually decreased to asingle horizontal line. The DC voltages atpins 13 and 14 of the TA8718N colourdecoder/timebase generator chip IC501were the same, so the linearity feedbackloop was working. But the voltage wasonly 4.5V instead of 6.7V, and didn't varywhen the height control was adjusted.When I checked the ramp generatorcapacitor C303 (2.2g) I found that it hada 2MQ leak. A replacement (tantalumtype) restored the height, but the picturewas not centred vertically because ofnoticeable non -linearity in the top third ofthe screen. C317, another 2.2RFelectrolytic, in the linearity feedbackcircuit was then found to have a 901d2leak. A tantalum replacement (35Vinstead of 50V) cured the non -linearity.P.L.

Mitsubishi CT25A5STX (Euro14SF chassis)This set came in with field collapse and aquick check revealed that circuit protectorZ551 had blown. The AN5521 fieldoutput chip IC451 was OK however. Coldchecks showed that IC5E1 (TEA2031A)on the EW sub -module was short-circuit.A replacement lasted only a few minutesbefore it failed however, the cause beingshorted turns on the EW loading coilL555. Another TEA2031A chip and anew coil (SEME part no. TPAR2343)completed the repair. P.L.

JVC 14E1EK (Onwa chassis)There was an interesting power supplyfault with this set, which was reported tobe dead. After carrying out cold checkswhich showed that the chopper and lineoutput transistors and the 12V regulatorwere intact, I replaced the two 47RFelectrolytics in the power supply beforeswitching on - very important with thischassis if further damage because ofexcessive HT is to be avoided. The setremained dead, with 300V DC at thecollector of the chopper transistor. So Iwent straight for the 3301c52 start-up

resistor R913, but this turned out to beOK. After spending some time isolatingand checking all the components in thepower supply I finally discovered that thechopper transistor had base -emitterleakage of about 700k.Q. As a result thestart-up voltage was being reduced to justbelow the minimum required to get thechopper transistor to conduct.

A new 2SD1545 transistor and someattention to dryish joints got everythingworking again. Upgrade kits for thispower supply are available from variouscomponent suppliers. R.M.

Mitsubishi CT2525TX"Dead" was the somewhat unhelpful faultdescription with this set. In fact it was farfrom dead: the red power lamp was alight,and most of the power supply, includingthe HT section, was working correctly.The cause of the problem was loss of the5V supply at the microcontroller chipIC701. I found that there was only 4V atthe input of the 5V regulator IC952,which was therefore unable to produce anoutput. Reservoir capacitor C956(2,200g) had dried up - and leaked forgood measure. A replacement restored12V or so at the input to IC952 and thecorrect 5V output.

But the set still refused to come out ofstandby. Some time, far too much in fact,was spent checking the circuitry aroundthe standby control transistors Q950 andQ951 before the penny dropped. Theowner had removed both batteries fromthe remote -control unit! D.I.S.

B&O 31/63Despite its striking looks this twelve-yearold set's circuitry appeared to be largelyconventional. The owner's complaint wasthat it kept reverting to standby. It didn'ttake long to find the cause, fatigued jointsat the edge connectors that link the twopower boards together. Many of theelectrolytic capacitors had clearly seenbetter days however - some evenappeared to be leaking. So they werereplaced as a precaution against furthertrouble.

This restored correct operation, but Iwasn't over -impressed with the picturequality. It seems to me that the darkPerspex outer screen serves only to reducethe picture colour, contrast and,especially, brightness to unacceptably lowlevels, requiring over -correction with thecontrols. D.I.S.

Samsung WI28W6VD (SCT53Achassis)At switch on the set would be OK andwork for about ten minutes. There wouldthen be a strange sound from the power


supply and the set would go to standby.This would be followed by continuouspowering up and tripping. Use of freezerenabled me to find the cause of the fault,which was the 7.5V zener diode DZ808.Normal operation was restored once thisitem had been replaced. The part number is0403-000562.

This chassis tends to suffer fromEEPROM corruption. You need to go intothe service mode and carry out a factoryreset. B.B.

Tatung T28NE51 (EIW and ElNchassis)The problem with this set was flyback linesat the top of the picture. The thing to dowhen you get this fault is to check resistorsR422 and R437 (both 12Q, 0.5W) whichtend to go high in value. They are surgelimiters in the supplies used by theTDA8350Q field/EW output chip IC401.B.B.

Sharp 56FW-53H (DA100chassis)The symptoms with this set were sound butno picture, because there was no linetimebase operation. Checks in the lineoutput stage showed that D610 (1N4933)was short-circuit. A replacement restorednormal operation. It's as well to check fordry -joints at C613. B.B.

Sharp 59DS-05H (CA10chassis)There was no picture with this set. Checks inthe line output stage showed that L604 hadbeen overheating while R613 was open -circuit. The cure was to replace C613(680nF, 250V), C619 (22pF, 160V) andR613 (221a 2W). Q602 (BUH515) shouldalso be checked. B.B.

Goodmans TVC201TThere was no TV operation with this unit,though the VCR section worked normally.C413, which should be 10pF, 250V, hadfallen in value to only 1pF. P.T.

Sony KVX2962U (AE2 chassis)When the problem is intermittent loss ofteletext you will usually find that the edgeconnector on board V is corroded. Athorough clean up normally does the trick,but in severe cases you may have to replacethe connector and pins on the main board.P.T.

Philips CT2309/05WThe symptoms with this set were no pictureor sound and a loud noise as if it was off -tune. The channel indicator was alight. Thecause was R3586 (22Q, safety) being open -circuit because of dry -joints in the lineoutput stage. P.T.

Sony AE1 chassisThere were no results and a check revealedthat the 2A circuit protector PS601 in the

15.5V supply was open -circuit. No obviousreason for its failure could be found, but Idecided to replace the associated 1,000pF,25V reservoir capacitor C615 as it is knownto cause problems with this supply. Oncethe replacements had been fitted there wassound and a picture, and a soak test provedthat all was now OK. B.F.

Huanyu 37C-3There was no sound or picture and awhining noise came from the powersupply. The cause was traced to an`invisible' poor connection at L782, whichis in series with the emitter of the lineoutput transistor. B.F.

Toshiba 2505DBTThe symptoms with this set were reducedheight with wavering bars all over thepicture. There was a common cause, C317(2.2pF, 50V) in the field linearity feedbacknetwork. There was a good picture once areplacement had been fitted. B.F.

Daewoo CP365 chassisThe cause of an intermittent crackle onsound, with no visible effect on the picture,was traced to an 'invisible' poor connectionat C808 (270pF, lkV), which is connectedto pin 3 (primary winding) of the choppertransformer. B.F.

Panasonic TXC21(U4 chassis)The cause of failure to power up with noaction from the relay was traced to R1351(0.68Q, 025W fusible) on the front Mboard. No reason for its demise could befound, and its replacement followed by along soak test proved that all was then OK.B.F.

Thomson 72MK89D (ICC11chassis)We sold hundreds of these sets, some ofwhich are now returning with various faultsymptoms. One common problem is loss ofluminance. A look at the manual issomewhat daunting, as the Y signal path isvia a lot of discrete -component circuitry(approximately fifteen surface -mountedtransistors), half of which is on a vertically -mounted screened video module. Thecircuitry can be broken into mid -way byconnecting a scope to pin 14 of plug/socketBV001. Missing or crushed video here hasalways been caused by T130, T132 or T134in the IF module. If a good signal is presentat pin 14 of BV001, the cause of the faultcan be narrowed down by removing thescreening from the video module to providelimited access to some of the transistorshere for scope checks. If no signal reachesTV001, TV681 and/or TV682 have beenthe cause. If there's a good signal at TV001,TV002 and/or TV003 are faulty.

A common problem that's beginning todevelop with this chassis is excessivebrightness with flyback lines. The cause is

resistor RL128 (1.8MQ), which is at theearthy end of the Al/G2 potential -dividernetwork. This component is mounted onthe dynamic focus module. A.J.

JVC AV29TS2EKThis set would power up and an EHTrustle could be heard. It would then almostimmediately shut down. A useful clue,noticed as the set shut down, was a rasterof reduced size all round. The flybacktuning capacitor C521 was open -circuit.We've since had two more of these setswith the same fault. A.J.

Sharp 66ES03H (CAI 0 chassis)The usual simple cause of a dead set is adry -joint at C613. This destroys the lineoutput transistor Q602. In this case theline output transistor ran very hot, whilethe set 'squeaked'. For some reason C613had gone open -circuit as well as beingdry -jointed, while R613 had burnt out.Nothing else had been damaged. C613 is680nF, 250V, part no. RC-FZ6684BMNJ;R613 is 2.2kS2, 2W, part no. VRS-VV3DB222J. M.S.D.

Samsung TI14C5This combi unit was dead. The cause wastraced to the optocoupler. M.S.D.

Toshiba 3738DB(C8SS chassis)There was no sound in any mode, justmotorboating from the rear speakers. As Iwanted to repair this set in the customer'shome if possible, I made a quick call toToshiba's excellent technical chaps. Weall agreed that the most likely culprit wasthe Dolby Digital module, item U101A,part no. 23781658. It's quite easy toreplace - simply unclip everything,remove the board, unsolder four lugs andunplug the old unit, not forgetting thesideways connector that goes into the IFblock. Unfortunately there was still nosound when this had been done.

So out with the meter to check the 35Vsupply to the two LA4282 audio outputchips Q601 and Q602. This is best done atpins 24 and 23 of the blue hinged plugBB12 from the power board. The supplywas pulsing up and down, so there was ablown output chip. Unsoldering pin 10 ofQ601 and Q602 in turn proved that Q601had failed.

At this point the owner revealed thatsomewhere along the cable run he hadwired in a third surround speaker ofdubious origin. He had used Elastoplast inlieu of insulating tape, and then fixed theconnection under his carpet on a nicesharp gripper rod! Why do people spend asmall fortune on a TV set that's too big fortheir house, too heavy to lift, and then dosuch stupid things?

After fitting a new LA4282 chip, partno. 23318413, and some new wiring allwas well. M.S.D.


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As some of you will probably haveguessed from my recent writings

I'm now semi -retired. This means moreholidays but, unfortunately, less technicalstuff to write about. We've just returnedfrom Greece, where I managed to dam-age my mobile phone while disconnect-ing it from my Apple Mac iBook com-puter after attempting to send e -mails. Ithad worked fine in the UK.

Next day my wife drove us along thetreacherous mountain road from Stoupato Kalamata so that I could buy areplacement. Once we'd parked in thetown we headed for the nearest tavernafor lunch. When I went to the bar to payI asked whether there was a telephoneshop nearby. There was, just around thecorner. It had a Panasonic sign abovebut was dark inside - and neither the

Photo 1: A typical digibox CPU chip mounted on the PCB.

tkk;{.Y1k10Zt,tITCI

Photo 2: Addition of a fan and heatsink to improve heat dissipation, greatly improv-ing CPU reliability

proprietor nor his assistant spoke a wordof English. So I had to resort to "teele-phono kaput". This seemed to work,because the proprietor took my phoneand scrutinised it closely.

"It went off when I disconnected itfrom my computer" I explained.

"Nai kimpootor. Ego echno ena kom-pootor. Teelefono leeootiree?" hereplied.

"Great" I said, "can you fix it? We'rehere for only a few hours. Could you doit now?" I was told to come back at two,before the shop shut for siesta.

We looked around the town for anhour then returned. "Is it fixed?" I asked

It was, and some further tricky con-versation elicited the fact that the memo-ry chip had had to be replaced. As Icouldn't gather what the cost was theproprietor scribbled 65 on a scrap ofpaper. Good grief, sixty five euros!

The phone was working again but Ididn't dare reconnect it to my lap -topPC. I found an internet café and askedhow much they charged per hour. Theowner looked surprised - apparently heusually rents use of the equipment for nomore than twenty minutes at a time. Butthere were 170 e-mail messages awaitingmy attention. Most were junk, but somerequired answers. So I sat down at themonitor for an hour while my wife wentto look in shop windows.

A PC faultWhen we arrived back in England wewere welcomed by the usual Manchesterrain. Which fool had thought of holdingthe Commonwealth Games here? Theydidn't expect sunshine, surely?

It felt strange to be back in the work-shop next day. I soon had a caller, whopresented me with a computer mother-board. "Look at those capacitors" hesaid.

There was a row of 1,500µF elec-trolytics, several of which were bulging.I didn't need my Genie ESR meter to tellme they were dead.

"The PC's been playing up for weeks"


he continued. "Thought it was Windowsuntil I opened it up and saw them. Do mea favour and fit some new ones."

The PCB had plated -through holes,which made it difficult to remove thefaulty electrolytics. I managed it by hold-ing my soldering iron in one hand to meltthe solder and my desoldering iron in theother hand. After half an hour I'dreplaced all eleven capacitors. I had noway of testing the board, but Glynphoned next day to say that the repair hadbeen a success. The board carried theidentification ABIT BX133/raid.

Very few shops bother to do compo-nent level repairs on computers. It can beworthwhile in a case like this.

DigiboxesThe subsequent hot, humid weatherbrought lightning storms and a spate ofdigibox repairs. Curiously, the majorityof the injured boxes were Panasonicones. Most required nothing more than afuse and a 1N4007 diode. There havealso been some other faults: I'll return tothese in a minute.

The CPU heat problemAll CPU (central processor unit) chips,e.g. microprocessors and microcon-toilers, give off heat. The faster they run,the more heat they give off. The tempera-ture at the centre must not exceed about200°C - at this temperature the outsidecasing will certainly be hot enough tohurt if you touch it.

Provided a digibox is kept in a coolroom with plenty of ventilation and airmovement around it, the CPU chip willprobably be safe. Unfortunately manydigiboxes are installed in rooms that havecentral heating, where the ambient tem-perature can be as high as 24°C in winterand 30°C in summer. To make mattersworse, the digibox may be installed in atight space, perhaps even in an enclosedcabinet.

A gap of a few centimetres above adigibox is simply inadequate. Hot airdoesn't move sideways without help. Itneeds a minimum gap of 100mm to moveupwards before it can spread outwardsand escape. In addition there must beplenty of room beneath and at the sidesfor cooler air to enter. Hot air can't comeout unless cool air goes in - otherwisethere'd be a vacuum!

SatCure (http://www.satcure.co.uk)provides a solution to this CPU reliabilityproblem. It takes the form of a coolingfan kit with heatsink. Here's how itworks.

The CPU chip is in a large squareplastic moulding, see Photo 1, but theactive silicon bit is actually quite tiny -afew millimetres in diameter. The heat itgives off has to pass through a layer ofplastic, then be taken away by direct radi-ation (not very effective with the cover inthe way) or air convection (not very

Photo 3: Equipment for replacing digibox processor chips.

effective in a closed box). The heat willbe removed more quickly if a metalheatsink is placed over the plastic encap-sulation, with the air gap between the ICand the heatsink filled with thermally -conductive cream. The gap is extremelysmall, but would provide good thermalinsulation - hence the importance of thethermal cream. But only a tiny amount ofcream is required.

The heat spreads out quickly into themetal heatsink, whose fins provide alarge surface area. The result is moreefficient dissipation of heat by radiationand air convection. While the heatsinkhelps a lot, the addition of a fan will pro-vide further improvement. See Photo 2.

Why don't manufactures do this? Theobvious answer is cost. There's also thenoise, and dust that may cause problemscan be drawn in. In addition most digi-boxes will run for years with the CPUjust below the critical temperature.

Back to some specific problems.

CuresI had suspected for some time that prob-lems I've come across with Panasonicdigiboxes could be caused by high CPUtemperature. Unfortunately Panasonicdoesn't seem to supply spare parts or ser-vice information to independent repairshops, so we are left to guess. A TU-DSB20 I had in recently would switchitself to standby after about twenty min-utes and wouldn't come back on. Itseemed an ideal candidate for the CPUcooling treatment.

The heatsink plus fan provided a com-plete cure. I left the unit on and checkedit periodically for over two days duringvery hot weather. It worked perfectly

throughout the test. The customer wasvery happy, as I'd originally quoted £100for the repair.

A TU-DSB30 would go to standbyafter about an hour and not come backon. The heatsink alone cured the problemthis time. But I was concerned that thecustomer might still manage to make itoverheat in an enclosed cabinet (as theydo!) so I fitted the fan as well.

Yet another cause of the stuck -in -standby symptom with this model hasbeen reported by Michael Old. He saysthe front -panel ribbon connector shouldbe cleaned and reinserted in its socket inthe motherboard.

In all models whose number ends inS3 or above, e.g. the 2500S4, Pace uses a

ball -gate array CPU that's similar to theone in the Panasonic boxes. This devicealso runs quite hot but, thankfully, Paceis willing to supply parts and advice.Michael Dranfield has replaced several ofthese CPUs, but he had to spend severalthousand pounds on the equipmentrequired (see Photo 3).

If you happen to own one of the digi-boxes mentioned above, you could savemoney by fitting a SatCure CPU coolingkit before it goes wrong.

Michael Old has also reminded methat one of the causes of the "no satellitesignal" message with the AmstradDRX100 digibox is a faulty U104 chip -the one with the heatsink glued to it. The`glue' is actually thermally -conductiveadhesive, which is not cheap. Other caus-es of the symptom, previously mentionedin this column, are the tuner and, lessoften, a faulty 15MHz crystal. As far as Iknow U104 is not available as a sparepart.


DVDFault reports fromGeoff Darby

We welcome fault reports fromreaders - payment for eachfault is made after publication.See page 744 for details ofwhere and how to send reports.

758

Philips DVD701This player was dead following a powercut. Meter checks revealed that the powersupply was tripping. When cold checkswere made on the secondary side of thepower supply I found that D6240 wasshort-circuit. A replacement restored nor-mal operation.

Toshiba SD200BThe picture produced by this machineintermittently froze. A replacement laserunit, which comes as a ready -mounted andmechanically -aligned deck assembly,cured the problem.

There are no fitting problems with thismodel. You simply screw the new deck inas a replacement for the original one thenconnect it. The laser shorting points haveto be opened of course before you test theplayer.

Sony DVP-NS300The complaint with this DVD player wasthat "it jumped around on all discs". Itried the player and found that when it hadbeen running for a while it started freezingand 'blocking'. This is typical of lasertrouble, but the DVP-NS300 uses a deckassembly (KHM-250AAA) which wedon't usually have in stock. So I thoughtthat, as a first move, I would run the inter-nal diagnostics and auto set-up.

This procedure is normally carried outusing the remote -control unit. It involvesuse of the numerical buttons to select vari-ous items from the service menus. Ipressed Title, Clear and On/off insequence to get into the main service diag-nostic menu, but could get no farther asthis machine's handset doesn't have num-bered buttons, and no other buttons wouldenable me to get to option 1, auto set-up,then option 0 for "all" (disc types). Ieventually used a handset for another

Sony machine as this one did have num-bered buttons.

After resetting the EEPROM data youcarry out the first auto set-up with a stan-dard, single -layer disc. Initial recognitionand spin -up were OK. The focus servowas then switched on and appeared tolock. The adjustments continued to be OKuntil the sled motor was switched on. Atthis point the process consistently failedand set-up was automatically terminated,with disc ejection.

So a replacement deck assembly wasordered and fitted. When I ran the autoset-up to match the new deck to the elec-tronics, the single -layer disc set-up, thenaudio CD and finally dual -layer DVD set-up progressed faultlessly. The final datastored in the EEPROM was within thecorrect ranges for a normally -functioningplayer.

A final soak test in the ordinary playmode proved that all was now well.

Hitachi DV-P250EIf the problem with one of these units isno display, check the green protector F3 inthe power supply. It's in the +5V feed tothe VFD inverter. When you find that thisprotector is open -circuit, a repair kit,TP12121, has to be obtained. It comeswith fitting instructions.

The modification involves replacing thetwo base bias resistors, uprating the tran-sistors and changing the feed point for thebias supply. The latter change calls for aprint cut and a link.

Sanyo JCX AVD-B501This is a home theatre system. If the trayrefuses to open, plug in a monitor to seewhat the on -screen display tells you. If"locked" appears briefly when theopen/closed button is pressed, press itagain and hold it in for five seconds or so,until the word "unlocked" flashes up atthe top left of the screen. The tray willthen open and close normally.

The lock mode can be re-engaged bypressing and holding the open/close buttonfrom the tray open condition.

Panasonic DVD-RV31Shortly after it started to play a disc thisunit just froze. I invoked the built-in jittermeter (operate the front -panel Pause andStop buttons and the remote -control 5 but-ton together) which produced a reading of011, i.e. 11 per cent, while the unit played.In theory this is within tolerance but, aspreviously mentioned in this column, it'shigher than one would expect from experi-ence with a correctly -functioning laser.

A replacement optical block wasordered and fitted. When checked this oneproduced an immediate, and long-termstable, jitter factor of 078, i.e. 7.8 per cent.No further adjustment was required - thisis a very good figure, unlikely to be bet-tered by mechanical tilt adjustment.


provides helpfulworkshop hints and tips

As promised last month, this time somenotes on servicing the Beko C14 chassisand on cheap Daewoo VCRs.

The C14 chassisI have to say that I like this chassis, whichis manufactured in Turkey by BekoElectronics. As with any chassis, there area few faults to which it is prone. But over-all it's reliable, produces good results andis straightforward to work on. You comeacross it in a number of sets, of both the4:3 and the widescreen variety, from vari-ous distributors. In the Bush range itsuperseded the 11AK19 chassis. There arevarious options, such as a built-in digitaldecoder and an internet box, and a rangeof sound systems from standard Nicam toDolby Surround.

The power supply is based on anMC44608 control chip, with a 2SK2545as the chopper FET. So far it has provedto be very reliable, and I've yet toencounter a fault in this area. However insome models the 2.5A fuse, ST601, hasfailed for no apparent reason. If you docome across a set with a short-circuit FETon the primary side of the power supply, Isuggest you also replace D609 (RGP10J).In addition R601 will have failed.

Apart from the 145V HT line, all thecircuits on the secondary side of thepower supply are protected by either fusesor fusible resistors. This traditionalapproach makes for easy fault-finding.Again I've yet to encounter any problemshere, but the most likely suspects in futurewill be the regulator ICs.

A tripping set indicates that there's aproblem in the line output stage, theLOPT being the number one suspect. Itusually develops a hole in the top andstarts arcing. Two different types are used,a Nokia and an Eldor. Either can be fittedwithout need to change any other compo-nents. The BU2508DF line output transis-tor gives little trouble.

The field output stage is based on aTDA8351/8356 IC. There's nothing muchthat causes problems apart from the ICitself. If you find that R521 (0.4752fusible) is open -circuit with no apparentcause, suspect C517 (22g, 63V) whichcan become leaky.

The catch with this otherwise reliablechassis is the sound circuitry, which con-sists of an MSP34XX series decoder chip

and a TDA7263 audio output stage. Theversion of the MSP device used dependson the sound options built into the set. Areplacement should be of exactly the sametype, but suspect this device only as a lastresort. The simplest fault is failure of theoutput IC: R341 (5450, 2W fusible) willalso have perished.

There can be problems with the capaci-tors in the sound circuitry, particularly thesurface -mounted ones, and these cancause some bizarre fault conditions.Should you encounter a weird sound fault,examine the surface -mounted capacitorsclosely with a magnifying glass. You willquite often find that one of them has split.Failing that, refer to the following list offaults I've encountered. If necessary,replace all the capacitors in the list.

(1) Randomly varying sound in one chan-nel: Replace C310 or C312 (10RF, 63V).

(2) Loud clicks from one channel with nosound: Replace C348 or C350 (100nF).

(3) No sound at all, but sound appearswhen the voltages around IC301 arechecked: Replace C235 (100nF).

(4) Oscillation in one channel: C348 orC350 has changed value. Should be100nF.

(5) Mono sound only, though the set dis-plays stereo: Replace C301 (2.2nF).

(6) No surround decoding: Replace C308(1.5pF).

(7) Loud click when changing channels:Replace C304 (100nF).

(8) Channels unbalanced: Replace C316and C319 (1nF).

Finally, to enter the service mode youneed a special engineer remote -controlunit. It's available from SEME.

Cheap Daewoo VCRsI'm sure that most of you will at sometime have found a cheap video on yourbench. You know the type I mean, one ofthose machines that costs only £59.99 andthe customer thinks it should last fortwenty years! You are expected to mend it

with change out of twenty quid . . .

Sadly, some of the parts used in thesemachines are lucky to make it through theguarantee period. There are Daewoomachines that seem to break down themoment you wave a video cassette any-where near them! Now don't get mewrong: Daewoo produces a range ofexcellent electronic products, includinggood -quality budget TV sets, but the relia-bility of its cheap videos is not good.

Fortunately they are not too difficult torepair. A high percentage of faulty onescan be returned to their owners quickly,without them having to re -mortgage theirhomes in the process! Poor heads are thenumber one problem. The slightestamount of tape dust can cause completeloss of the picture. It would seem logicalto replace the heads but, apart from thecost consideration (no pattern heads seemto be available yet), this is often notrequired. As with many other cheapVCRs, the back tension is set unnecessari-ly high. After cleaning the heads thor-oughly, reduce the back tension by turn-ing the adjuster 180° clockwise. Thisshould prevent the unit returning for aweekly head clean.

If the VCR has gone mad, suspect themode switch.

Most of the other problems are associ-ated with the power supply. The cheapelectrolytic capacitors quickly dry up andcause all sorts of faults. The worst offend-ers are the orange ones, so pounce onthese first. If the machine has a separatecan that contains the switch -mode mod-ule, unsolder and dismantle it then replaceall the electrolytics in it. Don't ignore theprimary side of the supply: there's a small47g electrolytic here that's critical forreliable operation. It's quicker and cheap-er to change all the capacitors than to tryto trace the cause of a fault to an individu-al one. I'm sure that kits will soon appear.Use 105°C, low-ESR types throughoutand you will have a machine that mightstill be giving good service in ten years'time. Well, maybe.

Next monthNext time I'll report on a widescreenDaewoo TV set that wouldn't turn onwhen the video timer was on or the cook-er was in use! Yes, it's true - but you'llhave to puzzle over why until next month.


I t was a welcome surprise whenDigger Pates phoned the other

day to report TV trouble. "HarveyPates?" I asked, "not Digger Pates,my old oppo of the Hampton Forddays? Blimey! Remember that`certain thing' we slipped intoyoung Miss Prude's handbag justbefore her first date with theCurate? Boy, we were somethingthen!"

I'd not seen Digger since our firstschool get-together over fifty yearsago. Just the same as ever! Alwaysa decent, easygoing chap. The sort Imight have been had the devil notmeddled with my genes. Sonysound trouble. Should be easy! Saidhe would pop his set in later thatday or tomorrow. Couldn't wait tosee him.

Confusion all roundMr Halwin interrupted my goldenthoughts as he headed for the doorcarrying a huge Fidelity TV set.Pity he tripped over Mr Millford'spoodle on its fifteen foot extendiblelead. The fuss delayed his entrance.Still, it gave me a chance to answerthe phone.

"Listen, Snoddy, I'm coming toput a clout on you!" it bawled.

I drew myself up. "How dareyou!" I bristled, "it's not thethought of the clout that gets me,but your confusion. I've beenmistaken for an aged and knackeredKirk Douglas on occasion, but balkat being mistaken for Snoddy!"

"Oh, sorry Mrs Bullock" said thevoice. "Forgot where I was!"

I looked into the phone'searpiece.

"Fact is, Snoddy's have had myHitachi set for ages, and thisweekend we've got visitors from

A LIFE!A vo ut things havechanged. Various TV faults and a dud CDplayer. Don Bull rvicing commentary

Australia.""Never mind the television set.

We do a nice line in tranquilisers" Iquipped. "But bring the Hitachi in."

Then Mr Halwin made it throughthe door, flew flying over a setwhich had just been placed on thefloor and landed his Fidelity set onthe counter. "Did you see thatlunatic out there with that mobiletrip wire?" he exclaimed. "Told meto look where I was going! Cheekof the man."

I looked at his set. "What's thetrouble?" I asked.

"Well, he's real thick, isn't he?"Halwin replied. "Got his mouthhanging open all the time."

"No, the set" I said."Ah, the set. Just shuts down after

a while. Riles me, I can tell you . .."At that Paul came in. So I took a

quick note of Halwin's details andtold him we'd give his a call whenthe set was ready.

DiagnosisPaul helped me carry it over to thebench, It was a 32in. set, ModelCTV3288. As it got warm thepicture clicked off. The soundremained.

"Ah, the line output stage" I said."But you haven't got the back off

yet!" Paul exclaimed, "I supposeyou're just clever".

"Well yes" I replied, "but it'slogical. Since the sound remainsand I know that the audio section ispowered by a secondary windingon the chopper transformer, thatseems likely to me."

Paul took the job on, because apleasant chap had come in andwanted to see me. He had a Sonyset with him, and I heard himmention the sound.

I looked at him. Yep, I thought,that's old Digger! Anybody'smoney on that!

I gripped his hand warmly. "HelloDigger old chap" I exclaimed."Wonderful to see you after allthese years!" I yanked up histrouser leg and tapped his angle."Remember that disgusting trickwe played on old ChalkyHargreaves with Dobson's hungryferret? Boy did that ferret find hisway about! Should have beenclassified as a dangerous weapon,that ferret!" As I laughed away Inoticed him giving me a strangelook.

"I'm Cyril Bamforth" he said."And I'm a registered councellor.Never had anything to do with aferret in my life. Don't like the lookof 'em. Just want my set mended."

"Er, oh, of course!" I spluttered."Sorry about that. Councellor, eh?You study oddballs? Ha, ha! Er,what's wrong with the Sony?"

"Sound" he replied. "Soundtrouble. First the left channel cutsout, then the right channel soundgoes. Sometimes all the soundgoes, leaving none at all."

"So you'd say it was soundtrouble" I continued, still put out bymy gaffe.

"Yes" he said, studying medeeply. "Yes, definitely." Then hehastily departed.

Repairs"This Fidelity" Paul said, "therewas HT but no line drive. I foundthe fault heat sensitive. Causeturned out to be the 2SC1573Atransistor Q580. A new one'scleared the fault."

"Oh, er right!" I said, "how abouthaving a look at this Sony set? It's


got intermittent sound problems."It turned out to be a Model

KVDX2112U (AE1 chassis).Sound was OK when we switchedit on. "Another iron and freezerjob" Paul said, seeking the audiooutput section. He soon found thatthe fault was to do with the audiooutput chip, IC251. By careful useof heat and freezer he managed toremove one channel at a time, orboth of them together. A newLA4280 chip restored reliablesound.

Intermittent operationThen the chap with the Hitachi setthat had been to Snoddy's came in.The back was off, and I saw a paneltumbling about inside. He fished inhis pockets for the back screws,and produced these as well.

"Have I had trouble" he said, "setall in bits, and that tall, thin Snoddychap tried to charge me 25 quid!Said they'd found the cause of thetrouble but wanted 95 quid to put itright. I roughed him up a bit, I cantell you."

"Of course" I repliedunderstandingly, looking at themess and hoping I could end upwithout getting a clout. "Whatname is it?"

"Basham" he replied. I eyed himsoberly and wrote it down.

When I'd settled the loose panelback in place I tried the set. It was aModel C2548TN (A6 chassis) andwas stuck in standby, though thestandby light reacted. Idisconnected the set and checkedone or two things, then plugged itin and tried it again. It worked.After a few more trials I found thatthis was its fault: sometimes itcame on, sometimes it didn't.

I decided to check the HTregulation feedback, and found thatR950 in the voltage sensingnetwork read 75k0 instead of681(52. That was enough to triggerthe protection circuit sometimes. Areplacement cured the trouble and,with Mr Basham firmly in mymind, I put the set togetherproperly and managed to work outa reasonable bill for him.

Missing signalsA tiny fellow with a huge set camein. Often happens. He was pantingwhen he put the set down on thecounter. Couldn't have been morethan five feet tall.

"What's the trouble?" I asked,after giving him a bit of time torecover.

"That bloody set" a fifty watt bassvoice bellowed, so loud that it

shook my chest. I looked about. Noone else there. So I backed away abit and hovered my pen over thejob card. "What name is it?" Iasked.

The amplifier bellowed out again."Biggs" the tiny chap said. "ThisSanyo set. No picture or sound.How long?"

I noticed an empty teacup rattlingin its saucer. Honestly! "Try thistime tomorrow" I said.

And off he went. The set was aSanyo C28EH27NB (EB3Achassis). It's not one with which weare familiar.

Steven decided to have a go."Needless to say, we don't have acircuit diagram" he commented.

"Times have changed" I said."There was a time when we hadeasily understandable,comprehensive manuals for prettywell all the sets that came in.Armed with an Ekco or Philipsmanual, set repair wasstraightforward. Now Ekco is nomore, and I can scarcely read aPhilips manual!"

"Can't imagine such an easy life"Steven said, turning to the set.When he applied power there wasno sound, but there was a faintraster.

He started to check around thechopper circuit. "That's odd hesaid" after a while, "every voltageis right, yet we've got these twoproblems. What can it be?"

He tidied a few bits and pieces offhis bench, blew his nose, turned offsome faint sound from a soak -testing set, and resettled himself onhis stool. Thus prepared, it wasn'tlong before he found that the signalstages weren't working. Hecompared the voltages around themicrocontroller chip with thoseshown on a circuit we did have fora similar model. The supply fromsomewhere was missing.

Checks at the tiny standbytransformer T381 showed that therewas voltage at one end of theprimary winding but not the other.It was open -circuit, and there wasof course no output from theassociated rectifier, which feeds asimple 5V series regulator circuit.

We e -mailed an order for areplacement transformer, whicharrived next day. When it had beenfitted the set sprang to life.

A CD playerOur next visitor was Ribby Ellis,the practical joker. For once he wasserious. "My bird's packed me up,Don" he told me.

"Don't blame her, Ribby" I

replied. "You're a non-stopheadache. Ladies need a chap whois brainy, successful and full ofcharm. A chap like me, not awalking disaster like you."

"Thanks for those kindly words"he said, "but the problem's to dowith her audio thing, not me. Said Icould mend it, but I can't get itgoing."

I felt sorry for him. "Where is it?"I asked.

He brightened up, went out to hiscar and returned with a SharpDXR555 CD payer. "It probablyisn't much" he said, "shall I get acup of tea going?"

"How do you know that?" Iasked, "what's wrong with it?"

"Dunno" he replied.There was a disc in it. I plugged it

in and tried it, but nothinghappened. I soon found that theblock drive motor wasn't working.I tried to help it, gently, and itresponded. So I put the tiniest traceof thin oil on its shaft, then stoppedto have a mug of tea with Ribby.He makes a good cup.

When we'd finished we tried theplayer again. It worked merrily."There you are, Ribby" I said."One trace of oil, half a penny.Knowing where to put it, twentyfour pounds, ninety nine pence andhalf a penny. Total £25, to you."

"That's exactly the price I chargefor my tea -making skills" he said."You're a pal, Don. Quits, eh?"

Set's outsideAs Ribby left a strip of rough -looking misery, about a hundredyears old, came in. He wasn't verygracious.

"Set's outside" he barked, "tooheavy for me. Anyway it's yourjob, not mine. Got somebody tobring it in?"

I went out and collected the set,then looked for a job card. "Whatname is it?" I asked.

"You ought to know that" hereplied. "Spoke to your boss about itearlier. Name's Pates. Now, I'm in ahurry for the set. Wife's on my backabout it. Can you look at it now?"

I looked at him. "Mr Pates?" Isaid, "Harvey Pates?"

"How did you know that?" hebarked. "You some sort of smartie?Before you answer, just watch yourlip. I know your boss, see. Dopeylittle chap. Likes things right, butnever could manage it. Anymessing me about and I'll makethings hot for you."

"Right sir" I said, "Sorry sir, I'msure. Now what was the troublewith it . ..?"


Solution to Test Case 478- page 741 -

It's fortunate that the LA7295 chip is not an expensivedevice, because the one that was removed - though itmay have been traumatised a bit - worked as well as itsreplacement. This is proved by the fact that the originalchip was refitted in the machine, which was returned toCynthia in full working order. Her son's £49-35 is, orwas, in Pam's till, while the new IC languishes in ourstores, probably never to be used.

Having established where everything ended up, wehad better describe how the repair progressed! The faultcondition and the voltage readings remained the samewhen the new IC had been fitted, so Cathode Ray turnedhis attention to the oscillator itself. It consists of tran-sistor Q401, transformer T401 and some tuning capac-itors. Checks on the transistor revealed that it was veryleaky collector -to -emitter, reading just a few ohms eachway with Ray's test meter. Stores couldn't provide a2SC3553C, but ECA's little yellow book pointed ouryoung man in the direction of an equivalent that workedperfectly well.

Not exactly high-tech stuff by today's standards, butall grist to the mill and money in the till. Ironically, thesame VCR had to be written off a couple of weeks laterbecause of a lightning strike. At least this one can'tbounce back on Cathode Ray, can it?

NEXT MONTH IN TELEVISIONGuide to the Thomson TX92 chassisThe TX92 chassis and its variant the TX92F (withfrequency- instead of voltage -synthesis tuning) wasused in a range of Thomson and Ferguson modelswith screen sizes 21in. upwards. Mark Paul provides adescription of the circuitry adopted for these chassis.

Motorised garage door controlRemote -controlled garage doors have become verypopular. Their control systems represent another areaof diversification that should be of interest tovideo/TV technicians. Keith Cummins describes theoperation of motorised garage doors, their controlsystems, and how to add an infra -red beam systemthat provides improved safety by preventing doorclosure if anything obstructs the entrance.

Sky+ updateBSkyB has recently updated its Sky+ personal videorecorder, adding new features and functionality. Thecompany has also announced that more features willbe launched either late this year or early next year.George Cole describes these developments.

Sony chassis guide updateOur last update on Sony models/chassis was in July1998. Giles Pilbrow bring us up-to-date with releasessince then.

TELEVISION INDEX & DIRECTORY 2002Plus hard -copy index and reprints service

Here's the essential repair information you need! TheTelevision Index & Directory 2002, in CD-ROM form,contains the text of over 14,000 high quality fault reports onTVs, VCRs, Camcorders, DVD players, Monitors, Satellite TVunits, Audio equipment and CD players, searchable by makeand model, plus the text of 168 Test Cases and over 200major servicing articles, from fourteen years of Televisionmagazine. It also contains a full fourteen year index ofTelevision, a Spares Guide, a directory of Trade andProfessional Organisations, an International TV Standardsguide, a satellite TV Channel Finder, a TV transmitter list anda compendium of internet resources for service engineers. Thesoftware is quick and easy to use, and runs on any PC withWindows 95, 98, ME, NT or 2000.

Television Index & Directory 2002 CD-ROM, £199

Television Index & Directory 2002 CD-ROM upgrade, £46(to qualify for this upgrade you need to have purchased aprevious version of the Television Index on floppy disk or onC D -ROM)

A six-month update of the index and fault reports will be avail-able in May 2002. If you wish to take advantage of this, £10should be added to a full update order.

Television Index only, 1988 - 2001, £36

Television Index only upgrade from previous versions, £16

Hard -copy indexes of Television magazine are availablefor Volumes 38 (1988) to 51 (2001) at £3.50 per volume.

Reprints of articles from Television back to 1988 are alsoavailable, at the flat rate of £3.50 per article - you can orderthrough our web site, or write to the address below.

The above prices include UK postage and VAT whereapplicable. Add an extra £1 postage for non -UK EC orders,or £5 for non -EC overseas orders, although Channel Islandresidents do not need to add any extra postage. Chequesshould be made payable to SoftCopy Ltd. Access, Visa orMasterCard Credit Cards are accepted. Allow up to 28 daysfor delivery (UK).

SoftCopy Limited,1 Vineries Close, Cheltenham, GL53 ONU, UK

Telephone 01242 241 455 Fax 01242 241 468e-mail: [email protected] site:http://www.softcopy.co.uk

Published on the third Wednesday of each month by Highbury Business Communications, Anne Boleyn House, 9-13 Ewell Road, Cheam, Surrey SM3 8BZ. High -bury Business Communications is a division of Highbury Communications PLC. Filmsetting by G&E Al Parkway, Southgate Way, Orton Southgate, Peter-borough PE2 6YN. Printed in England by Polestar (Colchester) Ltd., Newcomen Way, Severalls Industrial Park, Colchester, Essex C04 4TG. Distributed byComag, Tavistock Road, West Drayton, Middlesex UB7 7GE (tel. 01895 444 055). Sole Agents for Australia and New Zealand, Gordon and Gotch (Asia) Ltd.;South Africa, Central News Agency Ltd. Television is sold subject to the following conditions, namely that it shall not, without the written consent of thePublish-ers first having been given, be lent, resold, hired out or otherwise disposed by way of Trade at more than the recommended selling price shownon the cover, exclud-ing Eire where the selling price is subject to currency exchange fluctuations and VAT, and that it shall not be lent, resold, hired or otherwisedisposed of in amutilated condition or in any unauthorised cover by way of Trade or affixed to or as part of any publication or advertising, literary or pictorial matter whatsoever.

762 October2002 TELEVISION

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LLL:Broadcast Test Equipment & LCD Monitors

All Teletest productsare designed andmanufacturedin the UK

We require a full timeTV & Video service engineerRequired to assemble, test & repair our range of LCDmonitors and portable test equipment at ourBournemouth factory.Experience in the service industry essential.Call the number below for a job description.

Tel: 01202 646100Fax: 01202 646101Intl: +44 1202 etc

Call for a free infopack on our products.www.teletest co.uk

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www.mces.co.ukAmstrad, Pace, Grundig.

Digital set Tuner / PSU fault £35.00 plus VATtop Box Major fault £65.00 plus VAT

Amstrad DRX 100 tuner repairs £12.50 plus VATFault symptom "No Satellite Signal Received"

Pace "ZIF" tuner repairs £18.00 plus VATFault symptom "Picture freezes" or "No Satellite Signal Received"

Grundig Power Supply repairs £16.00 plus VATFault symptom "missing channels" and "No Satellite Signal Received"

M.C.E.S. DigitalE-mail: [email protected]

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WATCH SLIDES ON TVMAKE VIDEOS OFYOUR SLIDESDIGITISE YOURSLIDES(using a video capture card)

"Liesgang diatv" automatic slide viewer with built in high quality colour TV camera. It hasa composite video output to a phono plug (SCART & BNC adaptors are available). Theyare in very good condition with few signs of use. For further details see www.diatv.co.uk

£91.91+ vat = £108.00Board cameras all with 512x582 pixels 8.5mm 1/3 inch sensor and composite video out.All need to be housed in your own enclosure and have fragile exposed surface mountparts. They all require a power supply of between 10 and 12v DC 150mA.

47MIR size 60x36x27mm with 6 infra red LEDs (gives the same illumination as a smalltorch but is not visible to the human eye) £37.00 + vat = £43.4830MP size 32x32x14mm spy camera with a fixed focus pin hole lens for hiding behind avery small hole £35.00 + vat = £41.134OMC size 39x38x27mm camera for 'C' mount lens these give a much sharper imagethan with the smaller lenses £32.00 + vat = £37.60Economy C mount lenses all fixed focus & fixed irisVSL1220F 12mm F1.6 12x15 degrees viewing angle £15.97 + vat = £18.76VSL4022F 4mm F1.22 63x47 degrees viewing angle £17.65 + vat = £20.74VSL6022F 6mm F1.22 42x32 degrees viewing angle £19.05 + vat = £22.38VSL8020F 8mm F1.22 32x24 degrees viewing angle £19.90 + vat = £23.38Better quality C Mount lensesVSL1614F 16mm F1.6 30x24 degrees viewing angle £26.43 + vat = £31.06VWL813M 8mm F1.3 with iris 56x42 degrees viewing angle .. £77.45 + vat = £91.001206 surface mount resistors E12 values 10 ohm to 1M ohm 100 of 1 value £1.00 + vat1000 of 1 value £5.00 + vat

866 battery pack originally intended to be used with an orbitelmobile telephone it contains 10 1.6Ah sub C batteries(42x22dia the size usually used in cordless screwdrivers etc.)the pack is new and unused and can be broken open quiteeasily £7.46+vat = £8.77

Please add 1.66 + vat = £1.95 postage & packing per order

JPG ELECTRONICSShaws Row, Old Road, Chesterfield, S40 2RB

Tel 01246 211202 Fax 01246 550959 MastercardNisa/SwitchCallers welcome 9:30 a.m .to 5:30 p.m. Monday to Saturday

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Unit 17c Hartlebury Trading EstateKidderminster, Worcs DY10 4JB

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*PERIFELECMC 30 A Spectrum Analyser

Synthesized satellite cable and TV field strength meter withpanoramic reception on 14 cm (5,5") screen and digitalcarriers measurement.Complete microprocessor and IspLSI logic control.Continuous frequendes from 46 to 860 MHz and from 920to 2150 MHz on 4 bands.Selectable 4, I and 0,2 MHz spectrum band -width, picturemeasurement 1 MHz.Display of picture of selected synthesized channel.

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Display of full.band and 4 possible expanded spectrums.Channels and frequency plans of cable and N standards memorized.Frequency, signal strength in dBLN or bargraph, displayed on a digital display (2 lines of 16 characters).Voltage of remote power supply in 14v or 18v and 22 KHz in satellite DiSEq Co, v1.2 switching.

The panoramic field strength meter MC30A combines in one instrument all the functions necessary forinstalling and checking N or satellite reception, both analogue and digital. The visualization of the spectrumand the picture allows the carrying out of all the necessary adjustments with this one instrument. The hightechnology used in the MC30A allows a range of possibilities unheard of in a instrument in this price category.

f SAELTL ADue to its weight and size, the TC.402 ND is the idealinstrument for the installation of FM and terrestrial TV aerialsas well as CANsystems.

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TC 80 A/DThe TC BO ND has been designed for the reception of TV Satellite systems.

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TC 402 A/D

The TC80 A/D has been designed to aid the installation of analogue and digital satellite systems. This highquality meter has video and audio output via scan socket on rear and video only via BNC socket on front panel.The built in speaker delivers demodulated audio from any analogue satellite signals.

Full catalogue ofmeters available,please phone fordetails.

COASTAL AERIAL SUPPLIES Sole Importdadd. Distributors

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Tel: 020 8452 0161 Fax: 020 8208 1441www.cricklewoodelectronics.co.uk

E-mail: [email protected]

GAMMA UK LTD1501-1503 Pershore Road Stirchely

Birmingham B30 2JH

RE -FURBISHED VIDEORECORDERS BY A MAJOR

UK COMPANYOn release to the trade minimum quantity 10

PRICES START AT E 17 + VAT

All videos come with REMOTE, instructions andfly lead.

HITACHI, FERGUSON, SANYO,TOSHIBA, PANASONIC, AKAI,

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Fax: 0121 458 5558Email: [email protected]

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GOULD OS 300 OSCILLOSCOPE...,.., . DUAL TRACE

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466 Analogue Storage Dual Trace100MHz £250TEKTRONIX 485 Dual Trace 350MHz Delay Sweep £550TEKTRONIX 475 Dual Trace 200MHz Delay Sweep £400TEKTRONIX 4658 Dual Trace 100MHz Delay Sweep £325PHILIPS PM3217 Dual Trace 50MHz Delay ...E200 - £250GOULD 051100 Dual Trace 30MHz Delay £150HAMEG HM303 Dual Trace 30MHz ComponentTester £275HAMEG HN203.7 Dual Trace 20MHz ComponentTester £200FARNELL DTV20 Dual Trace 20MHz ComponentTester £125

MANY OTHER OSCILLOSCOPES AVAILABLE

MARCONI 2022E Synthesised AM/FM Sig Gen .£525 - £75010KHz - 1.01GHz LCD Display etcH.P. 8657A Syn 100KHz - 1040MHz Sig Gen £2000H.P. 86568 Syn 100KHz - 890MHz Sig Gen £1350H.P. 8656A Syn 100KHz - 990 MHz Sig Gen £995R8S APN62 Syn 1Hz 260KHz Sig Gen £425Balanced/Unbalanced Output LCD DisplayPHILIPS PM5328 Sig Gen 100KHz - 180MHz with200MHz £550Freq Counter IEEERACAL 9081 Syn AM/FM Sig Gen 5KHz - 1024MHz .£250H.P. 3325A Syn Function Gen 21MHzMARCONI 6500 Amplitude Analyser £1500H.P. 4192A Impedence Analyser £5000H.P. 4275A LCR Meter 10KHz - 10MHz £2750H.P. 8903A Distortion Analyser £1000WAYNE KERR Inductance Analyser 3245.. £2000H.P. 8112A Pulse Generator 50MHz £1250MARCONI 2440 Freq Counter 20GHz £1000H.P. 53508 Freq Counter 20GHz £2000H.P. 5342A 10Hz - 18GHz Freq Counter £800H.P. 16508 Logic Analyser 80 Channel £1000MARCONI 2305 Mod Meter 500KHz - 2Ghz £750

RADIO COMMUNICATONS TEST SETSMARCONI 2955/2955A from £1500Rohde 8 Schwarz CMT 0.1 - 1000MHz £2000Schlumberger 4040 £900

JUST IN

H.P. 60638 DC Electronic Load 3 -240V/0 -10A 250WP.O.A.

H.P. 66312A PSU 0 - 20V/0 -2A £400H.P. 663118 PSU 0 -15V/0-3A £400H.P. 66309D PSU Dual 0 -15V 0-3AJO-12V 0-1.5A 1750H.P. 66328 PSU 0 - 20V/0 -5A £500H.P. 6623A PSU Triple Output ranging from £8500-7V 0-5A to 0-20V 0-4AH.P./Agilent 34401A DMM 61/2 digit £400/£450H.P. 3478A DMM 51/2 digit £275FLUKE 45 DMM Dual Display £400KEITHLEY 2010 DMM 7,/2 digit £950KEITHLEY 617 Programmable Electrometer £1250H.P. 4338B Milliohmmeter £1500RACAL Counter type 1999 2.6 GHz £500H.P. Counter type 53131A 3GHz £850H.PJAgilent 33120A Function Gen/ARB £900/0000100microHz - 15MHzSONY/TEKTRONIX AFG320 Arbiter/ Function Gen..£1250H.P. 8904A Syn Function Gen DC - 600KHz£1000/£1250BLACK STAR JUPITOR 2010 Function Gen 0.2Hz - 2MHzwith Frequency Counter £140H.P. 8116A Pulse Generator 1mH-50MHz £1950H.P. 8657B Syn Signal Gen 0.1-2080MHz £2500CO -AXIAL SWITCH 1.5GHz £40IEEE CABLES £10

H.P. 85618 50Hz - 6.5GHz £6500H.P. 8560A 50Hz - 2.9GHz Synthesised £5000H.P. 8594E 9KHz - 2.9GHz £45001E5000H.P. 8591E 1MHz - 1.8GHz 75 ohm £3500H.P. 853A with 8559A 100KHz - 21GHz £2250H.P. 85588 with Main Frame 100KHz - 1500MHz £1250H.P. 3585a 20Hz - 40MHz £3000H.P. 3580A 5Hz - 50KHz £800ADVANTEST R4131B 10KHz - 3.5GHz £3500EATON/Ailtech 757 0.001 - 22GHz £1500MARCONI 2382 100Hz - 400MHz High Res £2000MARCONI 2370 30Hz - 110MHz from £500H.P. 182 with 8557 10KHz 350MHz £500H.P. 141T Systems8553 1KHz - 110MHz from £5008554 500KHz 1250MHz from £7508555 10MHz - 18GHz from £1000TEKTRONIX 491 10MHz - 12.4 GHz £500H.P. 8443 Tracking Gen/Counter 110MHz £250H.P. 8444 Opt 059 £750B 8 K 2033R Signal Analyser £750H.P. 5372A Frequency 8 Time Interval Analyser £2250H.P. 8754A Network Analyser 4MHz - 1300MHz £1250H.P. 3577A Network Analyser 5Hz - 200MHz E3000H.P. 53310A Modulation Domain Analyser Opt001/003 £5000ONO SOKKI Portable FFT Analyser £1500

USED EQUIPMENT - GUARANTEED. Manuals supplied.This is a VERY SMALL SAMPLE OF STOCK. SAE or telephone for lists. Please check availability before

ordering. CARRIAGE all units £16. VAT to be added to total of goods and carriage.


Available Now...EVERY ORDER* OF E12 OR M

USING THIS SALTTCHED CARRIAGE I

GeneralSpars SemeC eee,,

Seme

30Years

15 II

S LI 9APRIL 2002

PARCH. DESPATCHITOOF,A HON

The

SALICD CatalogueOver 750,000 products.

Brown Goods...White Goods...

Spares & Accessories.Finished Products.

CCTV.Over 7,000 colour pictures.Exploded View Diagrams.

Order CodeBenefit from...

Stock & Price Check prior to order submission

Gism`s Account Information page

access to your Account Status, ParcelDespatch Information & Outstanding Back Orders.

SALISALI

If you would like SALI including theSeme General Spares Catalogue

please contact salesand add to your next order.

On all SALT orders of£12.00 or more as well as`Applicable to Electronic orders only, excluggUrom credit

account customers.`Carriage rates exclude Seme Trade Supplies.

Tel: 01664 484000Fax: 01664 563976

email: [email protected] Seme"tit

ELECTRONICSWHOLESALE DISTRIBUTORS

OF DOMESTICELECTRONIC APPLIANCES

Unit 15 Marks Hall, Margaret Roding, Dunmow, Essex CM6 1QTTelephone: 01245 231684 Facsimile: 01245 231862

NAV t tELADIE ,27 MAI 'NAM PEMEuntE28in wide screen 16 x 9 format televisions . . from £190.00

untE32in wide screen 16 x 9 format televisions . . from £275.00

ILL1[2131 rear projection televisions 52" from £1,000.00

WE ALSO CARRY A UhtE SELECTION OFTELEVISIONS & VIDEOS ALL AT BELOW TRADE PRICES

36cm portables from £50.0051cm televisions fastit from £100.0059cm televisions nicam from £135.0068cm televisions nicam from £150.0078cm televisions nicam from £350.00videos 2 head mono from £50.00videos 4 head nicam from £60.00videos 6 head hi-fi nicam from £110.0036cm combined TV & video from £100.00dvd players £108.00

25cm televisions with DC 12/24 volt suitable for caravans -mobile homes - cars - kitchen use FROM £85.00

IN ADDITION WE ALSO CARRY: Microwaves from £39.00 Upright/cylinder/bagless vacuum cleaners from £23.00 A large range of audio/Hi-Fi equipment from £23.00

LARGE QUANTITY DISCOUNTS AVAILABLEALL PRODUCTS ARE FULLY GUARANTEED

We stock a great many other items in the TV, Video and domesticappliance range so if you don't see what you are looking for give us a call, we

will save YOU POUNDS.Visitors by appointment only

Use this coupon to order your copy ofPandora's drums

Please send me CD(s) at £11.99 eachincluding VAT

Cheque

Credit card details tick as appropriate

Name

Address

Phone number

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Make cheques payable to TELEVISIONOr, please debit my credit card.

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Please mail this coupon to TELEVISION, together with payment.Address orders and all correspondence relating to this order toPandora's drums, Television, Highbury BusinessCommunications, Anne Boleyn House, 9-13 Ewell Road, Cheam,Surrey, SM3 8BZ

Pandora's drumsUnique and atmospheric music recorded in theearly 1900s - the days before 78s.

Available exclusivelyfrom TelevisionAll tracks on this CD were record-ed on DAT from cylinders pro-duced in the early 1900s.Considering the age of the cylin-ders, and the recording techniquesavailable at the time, these tracksare of remarkable quality, havingbeen carefully replayed usingmodern electronic technology byhistorian Joe Pengelly.

21 tracks - 72 minutes of recordings made between 1900 and1929. These electronically derived reproductions are no worsethan - and in many cases better than - reproductions of early78rev/min recordings - some are stunning...

ServiceLink

PHONE 020-8722 6028FAX 020-8770 2016

BUSINESS FOR REPAIRS

SALE

BUSINESS FOR SALEDue to ill health

Kent/Sussex BordersEstablished 20 years

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Sales and Repairsand Rentals

tio last year £89,000

£35,000 + SAV01435 883552

FOR SALE

in tog/ELECTFIICS LIMITED

171 HAREHILLS LANE, LEEDS L58 30E

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MANUFACTURERS NEW GRADEDTICK MINT 14 RIGIN L A KI

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VIRTUAL DOLBY £286/639628"/32" PW 6816 REAL FLAT 50HZ DVD INT

VIRTUAL DOLBY 6376/647628"/32" PW 9525 REAL FLAT 100HZ

DOLBY 30 6547/241228"/32" DW 9625 100HZ REAL FLAT

INT. CARD READER DOLBY PROLOGIC 23991E599

OTHER MODELS IN STOCKPLEASE CALL FORA LIST AND PRICES

CREDIT CARDS WELCOME 48 HR DELIVERY

LINEAGECHEAPEST: REMOTE HANDSETS, TV& VIDEO, plug -tops, crimps, tapes,extension leads, time lapse video, printers,cableties, fuses. Tel: 020 7232 2266. Fax:020 7232 2288.

PANASONIC, MITSUBISHI, SONY,TOSHIBA, PHILIPS ETC,fully refurbished TVs. Trade only.Pearsons Television. Tel: 01484 863489

PRIVATE RETAILER has excellent partexchange colour televisions and videos toclear. Tel: 01494 814317.

SURPLUS SERVICE MANUALS FORSALE, mostly originals. Tel: 01291-623086with make/model.

Trade repairs toSky digiboxes

Pace, Amstrad, Grundig, Panasonic,(including Fluid Ingress).All makes repaired at a fair fixed price.

Scan Digital ServicesFor details

Give Alan a ring onTel/Fax: 01633 25 40 50

E -Mail: [email protected]

SKYDIGIBOXREPAIRCENTRE

Same day collection.Large stocks of refurbished

boxes.From £150 - call for details.

SERVICE DEPTS.D.S 01237 425999 / 470333

SALES DEPTThe Digital Centre,

Howard Avenue, Barnstaple,Devon, EX32 8QA

01271 325777 / 325888

accentTECHNICANALOGUE AND

DIGITALCAMCORDER

REPAIRSCollection anywhere in

the UK.All makes, ultra fast

service.Phone: 01905 771025

wwvi.accent-technic.co.uk

SERVICE DATA

SERVICE SHEETS AND MANUALS INNFor mostmakes and models of TV - Video - SAT - CD - Audio

CompleteS/Man

CTV - 10.00VCR -15.00

ServiceSheet4.006.00

Service sheets include circuits and essential electricalNCRmechanical set-up information.

All other items - price on application.Add P/P of £2.00 to order total. No VAT.Payment by cheque or P.O. only please.

D-TECPO BOX 1171, FERNDOWN, DORSET BH22 9YG

Tel: 01202 870656

ServiceInformation

Fryerns

FES CircuitDiagrams

TV's, VCR's, SATELLITEAUDIO, HI-FI's &CAMCORDERS

Most Models CoveredPrices are from £4.75 + £2.75 PIP

1 item - total £7.50 inc2 items - total £12.25 inc3 items - total £17 inc etc

note: some items priced individuallyPayment by credit card. P.O.

or chequeTel/Fax: 01206 211570

e-mail:[email protected]

2 The LodgeEasthorpe Green

Marks Tey, ColchesterC06 I HA

SERVICEMANUALS

Have you ever turned away workfor want of a Service Manual?

Have you ever bought a ServiceManual and never used it more

than once?Then why not join ...

THE MANUALS LIBRARYFor details and membership

application form write,phone or fax:

HARVEY ELECTRONICS43 Loop Road, Beachley, Chepstow,

Mons, NP16 7HE

Tel: 01291 623086 Fax: 01291 628786

Visa: Mastercard accepted

For a FREE consultation onhow best to market yourproducts/services to aprofessional audience

contact REUBENon 020 8722 6028

NEED HELP NOW?

Then ring the

* ELECTRON TECHNICALHELPLINE *

Genuine help available to all repairersof

T.V. V.C.R. - SAT - AUDIO (Inc Valves)- MICROWAVE - MONITOR AND

MOST ELECTRONIC EQUIP

Over 30 years experience and vast database

0906 470 1706Calls cost 60p per minute

Hours of Business Mon to Fri

9.00 am -12.30 pm . 2.15 pm -5.30 pm

Sal Morn 9 am -12 noonELECTRON G.T.

9 CHAPEL ST, DONISTHORPE,

SWADLINCOTE, DERBYSHIRE DE12 7PS

TVNCR CIRCUITS(WE DO NOT STOCKAUDIO OR MONITOR

INFORMATION)

TEL A.T.V. on0114 285 4254CTV Circuits from £5.00VCR Circuits from £7.00CTV Manuals from £10.50VCR Manuals from £14.50User instructions also available

(P/P add £2.50 to each order)

419 LANGSETT ROADSHEFFIELD S6 2LL

OPEN6 DAY

MANUAL COLLECTIONS PURCHASED.(POST 1995)

WANTED

BEST CASHPRICES PAID

For ALL valvesespecially KT88, PX4

and other audiotypes.

Tel: 01403 784961Billington Export Ltd

Sussex RH14 9EZFax 01403 783519

Email: [email protected] by appointment

component analyser

InC

0.1

C

0CO

LO

Check your semi's

MEASURESSINT°

Automatic componentidentification

Pinout identification

Transistor gain measurement

MOSFET gate thresholdmeasurement

PN junction characteristicsmeasurement

Shorted Junction identificationTransistor leakage measurement

Just connect the part any wayround and press the button!

Supports:Bipolar transistors,Darlington transistors,Diode protected

transistors,Resistor shunted

transistors,Enhancement mode MOSFETs,

Depletion mode MOSFETs,Junction FETs,

Low power triacs and thyristors,Diodes and diode networks,

Just plug one end of your cable into the Atlas IT and the other into the AtlasTerminator and press "test". In seconds the unit will identify the cable type(straight through, crossover or token ring) and verify every connection. Ifthere are any faults then they are clearly explained on screen.Socket testing is possible too thanks to the special patch cables included inthe outfit.Swapped lines, missing lines, shorted lines are all uniquely identifiedtogether with the full connection pattern!What's more, if you want to know how to make up a special network cable,the Atlas can instruct you, even down to cable colours!The Atlas IT is supplied with 2 non -ID terminators. 2 patch cnhles snarebattery, carry case and user guide.

Also available are ID terminatorsenabling cable -run identificatio

together with full connectionmapping and testing.

Up to 24 IDs available

OK Cross-Overcable (PC-PC

Connection

At las> 3614, -

Shorted lineddetected: 4 & 5

The Peakis analvsi

Two terminalbicolour LED

NPN bipolar

CurrenL.Hf°e=126

Enhancement.N-Ch MOSFET

Gate Thresholrqs=3.474)

money

c2Nnetwork cable analyser

OK Straieht thrucable (PC-Hub)

rminator ID-umber 04

be conneor Hu

01* - inclusive UK'price

supplied in earn' 'eis

Visit www,,peakelec.co.uk to do" oad the data sheets, user guidesand copies of independent reviews.You can pay using a cheque, postal order, credit or debit card andeven pay securely online. Please contact us for overseas or volumeorders - you will be pleasantly surprised.

electronic design ltd

Atlas House, Kiln LaneHarpur Ind. Est., Buxton

Derbyshire, SK17 9JL, UK

[email protected]

Tel. 01298 70012 Fax. 01298 70046

FarnellMAPUN

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PRONAA>eSELECTED ITEMS FROM THE PROW.

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MS 250Analogue and Digital Satellite Detector

PRODIG 1Satellite Dish Installer's Meter

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55 PVIt C;

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TA -901CRT Rejuvenator

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tips, guides and reports for people repairing televisions

Documents