Australia 85c; Malaysia $2.50; New Zealand 85c

SERVICING -VIDEO' CONSTRUCTION DEVELOPMENTS

Sign Circuit FaultsScopeTrace Doubler

MAK

MANOR SUPPLIESCOLOUR BAR GENERATOR

plus CROSS HATCH KIT (Mk. 4)

* Output at UHF, applied to receiver aerial socket.* In addition to colour bars, all R -Y, B -Y and Lum.

Combinations.* Plus cross hatch grey scale, peak white and black

levels.

* Push button controls, small, compact batteryoperated.

* Simple design, only five i.c.s. on colour bar P.C.B.

PRICE OF MK4 COLOUR BAR & CROSS HATCHKIT £35.00 + 8% VAT + f1.00 P/Packing.CASES, ALUMINIUM £2.40, DE -LUXE £4.80, BATT.HOLDERS £1.50. ADD 8% VAT TO ALL PRICES!

ALSO THE MK3 COLOUR BAR GENERATOR KIT FORADDITION TO MANOR SUPPLIES CROSS HATCH UNITS.£25.00 + £1.00 p.p. CASE EXTRA £1.40. BATY. HOLDERS £1.50.ADD 8% VAT TO ALL PRICES.

** Kits include drilled P.C. board, with full circuitdata, assembly and setting up instructions.

** All special parts such as coils and modulatorsupplied complete and tested, ready for use.

** Designed to professional standards.** Demonstration models at 172 West End Lane, NW6.** Every kit fully guaranteed.

MK4 DE LUXE (BATTERY) BUILT & TESTED £58.00 + 8% VAT+ £1.20 P/Packing.

ALTERNATIVE MAINS SUPPLY KIT £5.78 + 8% VAT + 65p P/P.VHF MODULATOR (CHI to 4) FOR OVERSEAS £3.50.INFORMATION ON VIDEO TAKE -OFF FOR C.C.T.V.MANOR SUPPLIES TELETEXT 77 KIT (incl TEXASDECODER). Full facilities in colour. External unit. AEinput to set. Write or call for further information. Seeworking demonstration model! Easy to build and resultsguaranteed for every completed unit.

I XM 1 Ilkicoder f 130.101pp f1.00.Auxiliary Units5,01.110 p p. f 1.50

Ile I. use case514.511p p £1.04).

Add 12 ", YAticparatti Price Listinr Individual

init. di nilahlr

ChangesfromTeletextto picturewithoutswitchingaerials

Armchairsvntrol ofTeletextand T Vstations.

COLOUR, UHF 8 TELEVISION SPAREST.V. PORTABLE PROJECT LOPT, SCAN COILS, DRIVER £12.50;EHT RECT. £1.20; ELC1043/05 £5.50, CONTROL UNIT £1.00; VISGAIN, VIS SELECT (TESTED) £3.80; PACKS: I.C. £5.20, CAPSTANT £2.75, ELECTROLYTICS £3.20, CERAMICS £2.00, POLY-ESTER ETC. £1.35; PRESETS 90p, TRANSISTORS £3.90,RESISTORS £2.50, SEMICONDS £3.80, BRIDGE REC. £1.95, C10690p; BYX7 1/600 (2) £2.40; RELAY £2.25, CONTROLS £1.18; 6MHzFILTER 68p; COIL £1.00; AERIAL £1.00; p.p. 85p. MAINSTRANSFORMER £5.80 p.p. £1.00. OTHER PARTS AVAILABLE.WORKING MODEL ON VIEW AT 172 WEST END LANE. NW6.SPECIAL OFFER FOR SHOP CUSTOMERS, TOSHIBA 14" CRTBRAND NEW £12.50.TV TEST GENERATOR UHF MODULATOR £3.50 p.p. 35p.CROSS HATCH UNIT KIT, AERIAL INPUT TYPE, INCL. T.V. SYNCAND UHF MODULATOR. BATTERY OPERATED. ALSO GIVESPEAK WHITE & BLACK LEVELS. CAN BE USED FOR ANY SET£11.00 + 45p. p.p.* (ALUM. CASE £2.00 p.p. 75 ) COMPLETETESTED UNITS, READY FOR USE (DE LUXE CASE) £20.80 p.p.90p.' ADDITIONAL GREY SCALE KIT £2.90 p.p. 30p."NEW TYPE" UHF SIGNAL STRENGTH METER KIT £18.00p.p. 90p. (VHF VERSION £18.80 p.p. 90ps).CRT TESTER & REACTIVATOR PROJECT KIT £19.80 p.p. £1.30."TELEVISION" COLOUR SET PROJECT. MARK II DEMONSTRA-TION MODEL WITH LATEST IMPROVEMENTS. WORKING ANDON VIEW, SPARE PARTS STILL AVAILABLE.SPECIAL OFFER I.F. Panel, leading British maker, similar design to"Television" panel. Now in use as alternative inc. circuit and connectiondata, checked and tested on colour £14.80 p.p. 95p.STABILISER UNITS, -add on" kit for either 40V or 20V, £2.80 p.p. 35p.PHILIPS 210 or 300 Series IF Panels £2.50 p.p. £1.00.PHILIPS 210, 300 Series Frame T.B. Panels £1.00 p.p. 65p.PHILIPS 19TG 170 Series Timebase Panels £2.50 p.p. 90p.BUSH A823 (A807) Decoder Panel £7.50 p.p. £1.00.BUSH 161 TIMEBASE PANEL A634 £3.80 p.p. 90p.BUSH 161 I.F. PANEL A583 £3.80 p.p. 90p.GEC 2040 Surplus Panels, ex -rental. Decoder E5.00. T.B. £5.00 p.p. 90p.GEC 2010 Series IF or TB. Panels for spares £1.00 p.p. 85p.BRC 3000 Surplus/Salv Panels, Decoder £7.50, Video £7.50 p.p. 90p.DECCA Colour T.V. Thyristor Power Supply. HT, LT etc. £3.80 p.p. 95p.BUSH TV 300 portable Panel incl. circuit £5.00 p.p. 95p.BUSH TV 312 IF Panel (Single I.C.) incl. circuit £5.00 p.p. 65p.BUSH CTV 174 Decoder plus C.D.A. £8.50 p.p. £1.00.BUSH TV Portable Eleven Volt Stab. Power Supply Unit £3.80 p.p. £1.00.PYE 697 Line T.B. P.C.B. for spares, £1.50 p.p. £1.00.MULLARD AT1023/5 convergence yoke. New £2.50 p.p. 75p.DLIE delay line. New 90p p.p. 40p. AT 1025/06 blue lat. '75p p.p. 30p.PHILIPS G6 single standard convergence panel, incl. 16 controls, switchesetc., and circuits £3.75 p.p. 85p, or incl. yoke, £5.00. G8 Decoder panelsex Rental £5.00. Decoder panels for spares £2.50 p.p. 85p.VARICAP, Mullard ELC 1043/05 UHF tuner £5.50, G.I. type (equiv.1043/05) £3.50 p.p. 35p. Control units. 3PSN £1.25, 4PSN £1.50, 5PSN

£1.80, Special otter 6PSN Luxe £2.80 p.p. 35p. TAA 55050p p.p. 15p. SaIv. UHF varicap tuners £1.50 p.p. 35p.BUSH "Touch Tune" assembly, incl. circuit £5.00 p.p. 75p.VARICAP VHF, ELC 1042 £4.80, p.p. 35p. ELC 1042 on Pye P.C.B.£5.40 p.p. 85p. VHF Transistd. Turret Tuner £1.50 p.p. 85p.VARICAP UHF/VHF ELC 2000S £10.50 p.p. 65p.UHF/625 Tuners, many different types in stock. Lists available. UHFtuners transistd. incl. s/m drive. indicator £2.85; Mullard 4 position pushbutton £2.50, 6 position push-button £4.50 p.p. 90p. AE ISOL 30p p.p. 20p.TRANSISTORISED 625 IF for T.V., sound, tested. £6.80 p.p. 65p.PHILIPS 625 IF Panel incl. CCT 50p p.p. 65p.TURRET TUNERS. KB "Featherlight" VC11. Philips 170 series. GEC2010 £1.80. GEC 2018, 2019, 2038, 2039 5 position £4.20 p.p. 85p.TBA "Q" I.C.s. 480. 530. 540, £2.20, 550, 560C, 920 £3.20 p.p. 15p.HELICAL POTS, 100K. 4 for £1.20 p.p. 20p.PHILIPS 19TGI70 Mains Droppers, two for 90p p.p. 50pLINE OUTPUT TRANSFORMERS. New guar. p.p. 85p.BUSH 145 to I86SS series £6.95BUSH, MURPHY A816 series £8.50DECCA DR I, 2, 3, 12 1;123,

20/24, MS 1700, 2001, 2401 £6.80DECCA MS2000, 2400 £5.80FERG., HMV, MARCONI,ULTRA 850, 900, 950 Mk. I £7.30

95011, 1400, 1500, 1590 £5.90GEC 2000, 2047 series, etc £6.80INDESIT 20/24EGB £6.40ITT/KB VC2 to 53, 100,200.300£6.80MURPHY 1910 to 2417 series E6.95PHILIPS 19TG121 to 19TG156 £4.80PHILIPS 19TG170, 210, 300 £6.80PYE 11U, 368, 169, 769 series £6.80PYE 40. 67 series (36 to 55) £3.80PAM, INVICTA, EKCO,FERRANTI equivalents as above.SOBELL 1000 series £6.80STELLA 1043/2149 £6.80

SPECIAL OFFERSBUSH TV125 to 139. £2.80EKCO 380 to 390 £1.00EKCO 407 417 £1.00FERR. 1084 1092 £1.00GEC 448/452 £1.50KB VCI, VCII (003) £2.80MURPHY 849 to 939 £2.80REG 10 6, 10 17 etc.SOBELL 195. 282 to 8 £1.50MANY OTHERS SI ILL AV All kBL I

COLOUR LOPTS p.p. £1.00.BUSH 182 to 1122 etc £9.80MURPHY Equivalents £9.80DECCA "Bradford"

(state Model No. etc) £7.80GEC 2028, 2040 £9.20ITT CVC 5 to 9 £5.80PYE 691, 693.697 £17.80PHILIPS 08 £8.50

THORN 850 Time Base Panel, Dual Standard 50p p.p. 80p.THORN 3000, 3500 Trifler £6.60 p.p.85p. Others available.6.3V CRT Boost Transformers £2.90 p.p. 75p., Auto type £1.80 p.p. 45p.

CALLERS WELCOME AT SHOP PREMISESTHOUSANDS OF ADDITIONAL ITEMS AVAILABLE NOT NORMALLY ADVERTISED

MANOR SUPPLIES172 WEST END LANE, LONDON, N.W.B.(Nur W. Hampstead tube stn: 28, 59 159 Bus Routes) 01-794 8751

Mail Order: 64 GOLDERS MANOR DRIVE. LONDON N.W.11.PLEASE ADD 121% VAT TO PRICES (EXCEPT 8%)

COPYRIGHTIPC Magazines Limited, 1978. Copyright in

all drawings, photographs and articlespublished in Television is fully protected andreproduction or imitation in whole or in partis expressly forbidden. All reasonableprecautions are taken by Television to ensurethat the advice and data given to readers arereliable. We cannot however guarantee it andwe cannot accept legal responsibility for it.Prices are those current as we go to press.

CORRESPONDENCEAll correspondence regarding advertisementsshould be addressed to the AdvertisementManager, "Television", King's Reach Tower,Stamford. Street, London SE1 9LS. All othercorrespondence should be addressed to-Television", IPC Magazines Ltd., King'sReach Tower, Stamford Street, LondonSE1 9LS.

BINDERS AND INDEXESBinders (£2.85) and Indexes (45p) can besupplied by the Post Sales Department, IPCMagazines Ltd., Lavington House, 25Lavington Street, London SE1 OPF. Pricesinclude postage and VAT. In the case ofoverseas orders add 60p to cover despatchand postage.

BACK NUMBERSSome back issues, mostly those publishedduring the last two years, are available fromour Post Sales Department (address above)at 70p inclusive of postage and packing toboth home and overseas destinations.

QUERIESWe regret that we cannot answer technicalqueries over the telephone nor supply servicesheets. We will endeavour to assist readerswho have queries relating to articlespublished in Television, but we cannot offeradvice on modifications to our publisheddesigns nor comment on alternative ways ofusing them. All correspondents expecting areply should enclose a stamped addressedenvelope.Requests for advice in dealing with servicingproblems should be directed to our QueriesService. For details see our regular feature"Your Problems Solved". Send to theaddress given above (see "correspondence").

:i.:"40'`,: MAY

7T_M ED1NJuly1978

4,"*.44:444:,::4: 4:4W4x,

this month4. 2

453 Leader454 Teletopics

News, comment and developments.

Vol. 28, No. 9Issue 333

Y!:

456 Hot Pyes by Les Lawry -JohnsFaulty receivers seem to come along in groups: this timeLes has been beset by awkward faults on Pye hybridcolour receivers.

460 Wideband Signal PreamplifierA review of a wideband (covering the entire TVspectrum) signal preamplifier some months backrevealed considerable interest amongst readers in suchdevices. Construction of a high-performance amplifier isnow simple, since i.c.s designed for the purpose havebecome available.

462 Test Report: The B and K Model 530 Semiconductor TesterA detailed report on the performance of this versatile by E. Trundleand unusual piece of test equipment and its usefulnessfor servicing.

464 Faults Analysed by Robin D. SmithFurther fault experiences, mainly of the less commonkind and with particular reference to the Rank A823Achassis.

467 Service NotebookNotes on faults and how to tackle them.

468 Scope Trace Doubler for TV Use by /an PawsonA practical, inexpensive unit to enable a single -beam scopeto be operated in the chop or alternate dual -trace mode

470 Transistors in TV Circuits, Part 3 by S. W. Amos,This instalment looks at the use of transistors at C.Eng., B.Sc., M.I.E.E.line frequency, taking in not only the line timebase butalso a.g.c. circuitry and decoder circuitry driven byline -frequency pulses.

473 Next Month in Television474 Servicing Saba Colour Receivers, Part 5

A detailed coverage of the four -chip(TBA510/520/530/540) decoder used in thesolid-state H chassis.

478 Letters480 TV Servicing: Beginners Start Here . .. Part 10

This time the signal side of things, describing thecomposition of a TV channel and the path of the signalfrom the aerial to the vision detector.

486 Servicing the Philips G8 Colour ChassisConvergence, the tuner and tuning problems, and thei.f. strip.

490 Long -Distance Television by Roger BunneyReports on DX reception and conditions, news from abroad,and notes on the OTS-2 European experimental satellite.

493 Readers' PCB Service494 Your Problems Solved496 Test Case 187

by Roger Bunney

by G. R. Wilding

by P. C. Murchison

OUR NEXT ISSUE DATED AUGUST WILL BEPUBLISHED ON JULY 17

.54@.--`"-

by S. Simon

by M. Phelan

TELEVISION JULY 1978 449

Ex -EQUIPMENTMONO TUBES(tested)19" Rimguard £4.5023" Rimguard £6.0020" Rimguard £6.0024" Rimguard £7.50+ £3.00 p.p.

MONO TUNERS6 - button integrated allat £6.50U.H.F. P/ButtonD/S£1.25£4.50 U.H.F. P/ButtonS/S £6.50 Rotary £3.00+ Et p.p.

MONO LOPTSAll D/StandardLopts at £4.00+ £1. p.p.All S/Standardat £4.00 +ft p.p.

SPARESMONO PANELSi.e. Philips, Bush etc.£3.50 + £1 P.P.

Quotations forcompleteS/Hand chassis ifrequired. (Diff prices)

miSC.S/Output Trans.£1 + VAT + £1 P&P

F/Output Trans.+ VAT + £1. P&P

Scancoils £1.50 + VAT+ O. P&P. Other sparesavailable. please writeor phone for details.

VALVES (MONO & COLOUR)

PCL82 0.10 PCF802 0.10 PCC86 0.10 EY86/7 0.10 30PL1 0.25 PL509 1.00

PCL83 0.25 PCF805 0.25 PC97 0.20EY8/7 0.10 30PL13/4 0.10 PY500 1.00

PCL84 0.10 PCF806 0.10 PC900 0.10 DY8020.10 30P12 0.10 GY501 1.00

PCL85 0.10 PCF808 0.25 EF80 0.10PY800/1 0.10 3OF L1/2 0.25 PL508 0.50

PCL86 0.10 PCF80 0.10 EF85 0.10PL36 0.25 ECC82 0.10 PCH200 0.50

PF L200 0.10 PCC189 0.10 EF183 0.10PL504 0.25 ECC81 0.10 PCF200 0.50

PCF801 0.10 PCC86 0.10 EF184 0.10 PL81 0.10 ECH81 0.10 CEY510.15

30C1 0.10 30C15 0.10 6BW7 0.106/30L2 0.10 ECL80 0.10

30C17 0.10 30C18 0.10 ECC85 0.10U26 0.10 ECL82 0.10

PL83 0.10 PL84 0.10 EH90 0.10Please note there is 25p P.P. per order

D/STANDARD COLOUR SPARE PANELS

IF LUM CHROMA EHT REG CON S/OUTPUT POWER L/TB F/TBBush/Murphy 6.50 6.50 6.50 - - 6.50 1.50 6.50 - --GEC/Sobell 6.50 7.50 - - - 6.50 - - - 7.50Philips 6.50 9.50 - - - 7.50 - - - 6.50Decca 6.50 12.50 12.50 - - 6.50 2.00 8.00 - 6.00

(19" only)Thorn 2000 6.50 7.50 7.50 6.50 6.50 7.00 - 8.00 15.00 6.50Pye 7.50 7.50 9.50 - - 6.50 - - - 4.00Baird 6.50 8.50 8.50 - - 6.50 - - - 6.00

Postage & Packing £1.25

3/STANDARD

IF LUMBush 184 9.50 -GEC Hybrid 9.50 9.50Philips G6 S/S .----------___/------N 9.50 - ---------......_Thorn 3000 10.009.00Pye 691/693 15.00 7.50Thorn 3500 10.00 9.00Korting and other foreign PostagePanels available on request.

COLOUR SPARE PANELS

CHROMA VIDEO CON POWER20.00 - 8.00 6.0015.00 - 6.00 -

-..--,

1/113 F/TB15.00 -- 12.00- ___...--...... ;10.002-0700 10.0015.00 7.5020.50 10.00

._-.. r-----..10.00--- - 9.00.18.00 10.00 6.00 20.0018.00 - 15.00 -18.00 10.00 10.00 20.00

& Packing £1.25

COLOUR TUBES

19" 18.0019" A49.192 £2020" 20.0022" 25.0025" 18.0026" 32.00

Plus P & P £4

COLOUR TUNERS

Bush 6.50GEC 6.50PhilipsG6S/S 6.50Thorn 3000 6.50Pye 691/697 7.50Some new tuners in stockcan suppy on request. ManyForeign Tuners also availableon request. Plus P & P £1

COLOUR LOPTS

Most lopts availablefrom £7.00. BothBritish & Foreignmakes. Please ringor write.P & P per lopt £1

MISC.S/Output transformerfrom £1.50F/Output from £1.25Scancoils from £5.00P & P £1Other spares available onrequest.

OS PANELSSPECIAL OFFER

CHROMA £12.00

I.F. £10.00

POSTAGE & PACKING£1.25 PER PANEL.

MAIL ORDER TVs GOOD WORKING

COLOUR MONO

Pye 19" £50.00 22" £60.00 26" £70.00 20" & 24" S/S £16.00 Pye, GEC, Bush etc.GEC 19" £50.00 22" £60.00 26" £70.00 20" & 24" D/S £14.00 Pye, GEC, Bush etc.Bush 19" £60.00 22" £7 0 26" £80.00 19" & 23" D/S P/button £12.00 Pye, GEC, Bush etc.Philips G6 (N-,.._,-----,.....22" £58.00 26" £70.00 1 " D/S Rotary £8.00 Pye, GEC, Bush etc.

Many other makes & models available. PERSONAL CALLERS 24.% V.A.T. o all prices colour & mono.

Please ring or write for information. WELCOMEP & P £6.00 pe colour set. P & P £4.00 per mono set.

WHY NOT TRY OUR EXPRESS MAIL ORDER ON Y OF THE ITEMS LISTED.

PLEASE ADD 121/2% V.A.T. TO ALL ITEMS AND OVERSEAS AT COST. CASH WITH ALL ORDERS.

BRIARWOOD TELEVISION LTD.Legram Mills, Summerville Road, Bradford, West Yorkshire BD7 1NS Tel (0274) 306018

450 TELEVISION JULY 1978

TELEVISION SALEDISCOUNT FOR QUANTITY

BRIARWOOD TELEVISION LTD.Legrams Mills, Summerville Road, Bradford, West YorkshireBD71NS. y41:102741306018.

offered are new and branded. ManufacturedAll mtrroasirsdtoirsiTTexas,, ., ekes, Motorola etc.

Pleas add 12196") to all items and overseas at coat.

M ONO IP & 25p order, overseas allow for package and postage. Cash with all orders. All prices subject to alteration without notice

Rotaries 19" & 23" TYAls........--/ PRICE E TYPE PRICE E TYPE PRICE E TYPE PRICE E£ AC107 0.23 BC171 0.12 BF260 0.24 1N5404 0.12

GEC 3.00 AC113 0.17 BC172 0.12 ElF262 0.28 1N5406 0.13Thorn

AC115 0.17 BC173 0.15 8F263 0.25 1N5408 0.16950 etc. -------' ,-__--- 3.00 AC117 0.24 BC177 0.14 BF271 0.20 VALVESK.B. 3.00 AC125 0.20 BC178 0.14 BF273 0.12

AC126 0.18 BC179 0.14 BF336 0.35 DY87 0.52Pye 3.00 AC127 0.19 BC182L 0.08 BF337 0.24 DY802 0.64Thorn 1400 '.--------,----- 4.50..., AC128 0.17AC131 0.13

BC183L 0.07BC184L 0.11

BF338 0.29BFT42 0.26

ECC82 0.52EF80 0.40

AC141 0.23 BC186 0.18 BFT43 0.24 EF183 0.60D/S P/B 19" 23" AC142 0.19

AC141K 0.29BC187 0.188C209 0.14

BFX84 0.27BFX85 0.27

EF184EH90

0.600.60

___ AC142K 0.29 BC212 0.13 BFX88 0.24PC86 0.76

AC151 0.17AC165 0.16AC166 0.16

BC213L 0.09BC214L 0.14BC237 0.07

BFY37 0.22BFY50 0.188FY51 0.17

PC88 0.76PCC89 0.65PC189 0.65

4.,.._ .1400 _--triiFT6-1----- '7:00 -L

66D-eter --- - __ 7.0 AC168 0.17 BC240 0.31 PCF80 0.70BFY52 0.18 PCF86 0.68Philips 210 etc. 760Pye Olympic etc. 7.00

AC176 0.17AC176K 0.28AC178

BC281 0.24BC262 0.20BC2638

BFY53 0.27BFY55 0.27

PCF801 0.70PCF802 0.74

0.16AC186 0.26

0.20BC267 0.19

BHA0002 1.90BR100 0.20

PCL82 0.67

D/S P/B 20" 24 " AC187 0.21AC188 0.208C301 0.26BC302 0.30

BSX20 0.23BSX76 0.23

PCL84 075PCL8 .

805 .70c£ AC187K 0.34 BC307 0.10 BSY84 0.36 ,ertoo......,...-PBush 10.00GEC 10.00

AC188K 0.34AD130 0.50AD140 0.65

BC337 0.13BC339 0.09BC307A 0.12

BT106 1.18BT108 1.23BT109

PL36 0.90PL84 0.74

Philips 10.00Pye 10.00

AD142AD143

0.730.70

AD145 0.70

BC308ABC309

0.120.14

BC547 0.09

1.098T116BT120

1.232.08

PL504 1.00PL509PY88

2.450.63

Thorn 10.00 AD149 0.64AD161 0.41 BC548BC5490.110.11

BU105/02 1.87BU105/04BU126

2.251.40

PY500A 1.50PY81/800 0.57

E.H.T.TRAYS MONO950 MK2 1400 2.26 ..N.eS/S 20" 24" £

AD162 0.48AD161 t

1.30BC557 0.11BD112 0.39

BU205 1.97BU208 2.49

Bush 313 etc. 12.00Pye 169 chassis 12.00Thorn 1500 ,________,--.,..___,--......12.00

AD1621AF106 0.42AF114 0.23AF115 0.22

BD113 0.65B0115 0.40BD116 0.47

801241.30

BY126 0.09BY127 0.100C22 1.100C23 1.30

1500 18" 19" stick2.37 \ \ /..

150024"' 5 stick 2.48 \ISingle stick Thorn TV

GEC & 2 AF116 0.22BD131 0.32 0C24 1.30 11.16K 70V 0.75series 1 12.00 AF117 0.22 BD132 0.34 0C25 1.00 TV 20 2 MT 0.75Decca MS series,-------------, 12.00 AF118 0.40 BD133 0.37 0C26 1.00 TV20 16K 18V 0.75

AF121 0.43 BD135 0.26 0C28 1.00SN76013INC's 1.48SN76013ND 1.20SN76023N 1.50

S/S COLOUR19" 20" 22" 25" 26"

AF124 0.33AF125 0.29AF126 0.29

BD136 0.26BD137 0.26BD138 0.26

0C35 1.000C36 0.900C38 0.90

£ £ £ £ £AF127 0.29AF139 0.39

BD139 0.40BD140 0.28

0C42 0.450C44 0.20

SN76023ND 1.20SN76226DN 1.50

GEC 40 45 45 45 50 AF151 0.24AF170 0.25 BD145BD144

1.39030 0C45 0.200.35

SN76227N 1.20

Philips - - 451 4-5 50 AF172 0.20 BD222/T1P31A 0.39 0070C460 0.22 TBA341 0.97TBA520Q 1.45Thor 60 - r 65 85

S 60 - 75AF178 0.49AF180 0.60AF181 0.30

BD225/T1P31A 0.39BD234 0.3480222 0.50

0071 0.280072 0.350074 0.35

TBA530Q 1.20TBA54013 1.45TBA550Q 1.60

Kort - - 65 - 75 AF186 BDX22BDX32 1.980.73 0075 0.35 TBA56OCQ 1.808,9, 0.43AU113 1.29 BDY18 0.75

BDY60 0.80

0076 0.350077 0.50

TBA570Q 1.00TBA800 1.00D/S COLOUR /

8F115 0078 0.13 TBA810 1.5019" '25"£ r ----"/Decca 20.00 25.00

Bush 20.00 25.00Baird 20.00 25.00GECPhilips

20.00 _2255..0000)- ___ -

BABA145

0.080.14

BA148 0.17BA155 0.10BAX13 0.05BAX16 0.08BC107 0.12BC108 0.12BC109 0.12BC113 0.12BC114 0.14

BF1210.240.21

BF154 0.19BF158 0.19BF159 0.24BF160 0.23BF163 0.23BF164 0.17BF167BF173

0.230.21

BF177 0.26

0081 0.2000810 0.140082 0.2000820 0.130083 0.220084 0.280085 0.130C123 0.200C1690C170

0.200.22

0C171 0.27

TBA9200 1.80TBA9900 1.60TCA270SQ 1.45TCA27OSATCA1327B

1.451.00

E.H.T. TRAYSCOLOUR

Pye 691 693 4.50Dacca (large screen)CS2030/2232/2630/

BC115 0.12 BF178 0.24 0A91 0.05 2632/2230/2233/PLEA NO E TI-tERE IS BC116 0.12 BF179 0.28 BRC4443 0.65 2631 5.67

124-% V.A.T.BC117 0.13 BF180 0.30 R2008B 1.50 Philips G8 520/40/50BC119 0.24 BF181 0.34 R20108 1.50 5.66Please not all sets sold as BC125 0.15 BF182 0.30 R2305 0.38 Philips G9 5.79

100% comp. No broken masks, no BC126 0.09BC136 0.14BF183 0.29BF184 0.23 R2305/BD222 0.37

SCR957

GEC C2110 5.50GEC Hybrid CTV 5.40

broken panels etc. BC137 0.14 BF185 0.29 0.81Thorn 3000/3500 5.50Colour sets sold with good c.r.t.s and BC138 0.2480139 0.21

BF186 0.30BF194 0.09

TIP31A 0.38TIP32A 0 36. Thorn 800 2.42Thorn 8500 5.23100% comp. 80140 0.31 8F195 0.09 TIP3055 0.53 Thorn 9000 6.10

Working Mono £3.00 extra. BC141 0.22 BF196 0.12T1591T1590 0.19

0.19 GEC TVM 25 2.50

Working Colour £10.00 extra.BC142 0.19BC143 0.19

BF197 0.10BF198 0.15BF199 0.14

TV106 1.09 ITT/KB CVC 5/7/8/95.50

Supplied in l's or 100's BC147 0.09 RRI (ABM) A823 5.89BF200 0.28BC148 0.09 Bang & Olufsen

BC149 0.09 BF216 0.12 DIODES 4/5000 GrundigWE DO NOT SELL RUBBISH BC153 0.12 BF217 0.12 1N4001 0.04 5010/5011/5012/

AT .. BC154 0.12.BC157 0.10BF218 0.12BF219 0.12

1N4002 0.041N4003 0.06

6011/6012/7200/2052/2210/2252R

BRIARWOOD T.V. LTDBC158 0.11BC159 0.11BC160 0.28

BF220 0.128F222 0.128F221 0.21

1N4004 0.071N4005 0.071N4006 0.08

Tandberg IradionettelAutovoxGrundig 3000/30106.60LEGRAMS MILLS, BC161 0.28 BF224 0.12 1N4007 0.08 Saba 2705/3715

SUMMERVILLE RD., BRADFORD. BC167 0.13 BF256 0.37 1N4148 0.30 Telefunken 709/710/TEI!...06018. / BC168 0.10801690 0.12 BF258 0.278F259 0.27

1N4751A 0.111N5401 0.10

717/2000 6.80Korting 6.80

TELEVISION JULY 1978 45

TRANSISTORS, ETC.

Type Price (£)AC107 0.48AC117 0.38AC126 0.38AC127 0.54AC128 0.48AC128K 0.65AC141 0.85AC141K 0.70AC142AC142KAC151AC152AC153AC153KAC154AC176AC178AC179AC187AC187KAC188AC188KAC193KAC194KACY17ACY19ACY28ACY39

0.600.650.310.360.420.520.410.450.510.550.560.650.520.610.700.741.200.950.982.02

A0140 1.79AD142 1.90AD143 1.78AD149 1.92AD161 0.68AD161/162 1.22AD162 0.71AF114 0.35AF115 0.36AF116 0.41AF117 0.42AF118 0.98AF121 0.68AF124 0.38AF125 0.38AF126 0.36AF127 0.86AF139 0.58AF147 0.52AF149 0.45AF178 1.35AF179 1.36AF180 1.35AF181 1.33AF 186 1.48AF202 0.27AF239 0.73AF240 1.40AF279S 0.91AL100 1.30AL103 1.52

Type Price felAU103 2.40AU107 2.75AU110 2.40AU113 2.60BC107 0.16BC108 0.15BC109 0.16BC113 10.22BC114 10.22BC115 10.24BC116 10.25BC117 10.30BC118 10.24BC119 10.34BC125 10.30BCI 26 10.30BC132 10.20BC134 10.22BCI 35 10.21BCI 36 10.22BCI 37 10.30BC138 10.32BC140 0.36BC141 0.44BCI 42 0.35BCI 43 0.38BC147 10.12BC148 10.12BC149 10.13BC152 10.42BC153 10.38BC154 10.41BC157 10.13BC158 10.12BC159 10.14BC160 0.528C161 10.58BC16713 10.15BC1680 10.14BC169C 10.15BC170 10.15BC171 10.16BC172 10.14BC173 10.22BC174A &

10.26BC176 0.22BC177 0.20BC178 0.22BCI 79. 0.28BC182 10.15BC182L 10.15BC183 10.14BC183L 10.148C184 10.15BC184L 10.15BC185 0.36BC186 0.25BC187 0.27

Type Price (VBC192 0.56BC204 10.39BC205 10.39BC206 10.37BC207 tO 35BC2088C209BC211BC212BC212LBC213BC213LBC214BC214LBC225BC237BC238BC239BC251BC252BC253BC261ABC262ABC263BC2679C268BC286BC287BC291BC294BC297BC300BC3018C302BC303BC304BC307BC3088C3098C317BC318

10.3710.3910.3610.1710.1710.1810.1810.1810.1810.4210.1810.1510.2210.2510.2810.3810.2810.2810.280.200.280.400.490.27

10.370.380.820.380.860.640.44

10.1710.1410.1810.1510.16

BC319 10.19BC320 10.17BC321A&B 10.18BC322 10.28BC323 1.158C327 10.16BC328 10.18BC337 t0.17BC338 t0.17BC340 0.19BC347 10.17BC348A & B

10.17BC349B 10.17BC350 10.24BC351 t0.22BC352A 10.24BC360 0.59

Type Price (f)BC377 0.29BC394 0.39BC440 0.52BC441 0.59BC461 0.78BC477 0.30BC478 0.25BC479 0.33BC547 10.13BC548 10.13BC549 10.15BC550 10.24BC556 10.23B C557 10.15B C558 10.16BC559 0.17BCY10BCY30ABCY32ABCY34ABCV72BD115BD123BD124BD130YBD131BD132BD13360135BD13660137BD13860139BD14060144801 45BD150A60155BD15760158601598016060163BD1656016680175813177801788018180182B01838018480187BD1888018980222802258023280233

0.301.061.191.020.271.351.601.851.560.580.880.70

10.3710.380.400.420.460.502.240.75

10.4110.900.810.750.882.690.670.660.880.900.580.921.942.101.342.301.201.250.710.780.910.910.82

Type Price (£)80234 0.8881323580236BD23780238802538041080433B043580436BD43780438805198052013059980600

0.630.630.680.681.581.650.650.700.710.740.750.880.880.871.23

8066386 0.8680X18 1.55BDX32 2.95BDY16A 0.43BDY18 1.55BDY20 2.20BDY38 1.38BF115 0.48BF117BF120BF121BF1238E125BF127BF137FBF152BF158BF159BF160BF1618F163BF164BF166BF167BF1738F177BF178BFI79BF180BF181BF182BF183BF184BF185BF186BF194BF195BF196BF197BF198BF199BF200BF218

Alternative gain versions available on items marked.

0.450.550.850.480.550.510.78

10.1910.2510.2710.200.84

10.6510.950.500.380.350.360.460.580.530.530.440.520.440.420.42

10.1410.1310.1410.1510.29t0.2910.2510.42

Type Price ICIBF222 10.51BF224 & J 10.22BF240 10.32BF241 10.31BF244 10.61BF245 10.43BF254 10.48BF255 10.58BF256L 10.49BF257 10.47BF258 10.52BF259 10.54BF262 0.73BF263 0.88BF270 0.47BF271 0.42BF272A 0.80BF273 10.33BF274 10.34BF336 0.63BF337 0.658F338 0.68I3F355 10.72BF362 10.49BF363 10.49BF367 10.29BF451 0.43BF457 0.46BF458 0.49BF459 0.52BF594 10.18BF596 10.17BF597 10.27BFR39 10.39BFR40 10.29BFR41 10.30BFR50 10.29BFR52 10.33BFR61 10.29BFR62 10.28BFR79 10.30BFR80 10.29BFR81 10.30BFR88 10.42BFT41 0.48BFT43 0.55BFW11 1.02BFW30 2.58BFW59 10.19BFW60 10.20BFW90 1.86BFX29 0.38BFX84 0.42BFY50 0.38BFY51 0.37BFY52 0.36BFY53 0.38BFY90 1.98BPX25 1.62

Type Price l£)BPX29 1.62EI6101 0.538610386303BRC4443BRY39BRY56BSS2761106BT109BT116BT119BU102BU105BU105/02BU108BU126BU204BU205BU206BU208BU407BUY77C106DC106FC111E04051E1222E5024GET872MC140ME0402ME0404ME6001ME6002MJ2955MJ3000MJE340MJE341MJE370MJE371MJE520MJE521MJE2955MJE3000MJE3055MPF102MPS3702MPS3705MPS6521MPS6523MPS6566MPSA05MPSA06MPSA55MPSA56MPSA93MPSLO1MPSUO1

0.641.060.960.65

10.440.921.501.991.455.182.85

11.8011.9512.98t2.9112.5012.7813.0914.8811.382.500.800.43

10.460.640.47

10.190.46

t0.3810.1810.1810.1810.181.301.580.680.720.740.790.850.951.201.951.22

10.4010.3310.3010.3610.3610.4410.3010.3210.4310.4510.5510.33

0.81

Type Price (C)MPSUO5 0.66MPSUO6 0.78MPSU55 1.28MPSU56 1.32MPSU60 0.82MPU131 10.590C26 1.900C28 1.490C29 1.600C35 1.250C36 1.250C42 0.900C44 0.680C45 0.630070 0.650071 0.730072 0.730081 0.83°C81 D 0.950C139 1.30OC I 40 1.350C170 0.800C171 0.820C200 3.900C201 3.950C202 2.400C205 3.95OCP71 1.98ON236A 0.946200813 12.62R20108 12.79R2322 10.75R2323 10.85ST2110 0.49ST6120 0.48TIC44 10.25TIC46 10.35TIC47 10.45TIP29A 0.47TIP30A 0.50TIP31A 0.61TIP31C 0.87TIP32A 0.56TIP32C 0.72TIP33A 0.77TIP34A 0.84TIP41A 0.72TIP42A 0.80TIP2955 0.77TIP3055 0.58TIS43 10.44TIS73 11.36TIS90 10.23TIS91 10.28ZTX108 10.14ZTX109 10.16ZTX213 10.20ZTX300 10.18ZTX304 10.26

For matched palm add 20p per pair.

Type Price ( f)ZTX500ITX502ZTX5042N4042N6962N6972N706A2N7082N914259162N918259302511642513042N13052N13062N13072N13082N17112N18932521022N22172N22182N22192N2221A2N2222A2N2369A2 N24012N24842N25702N26462N27842N28692N28942N29042N29052N29062N2926G2N292602N2926Y2N29552N30532N30542N30552N32502N32542N3391A2N36332N37032N37042N37052N37062537072N37082N37152N37712N3772253773253794

10.1810.2210.281.300.460.460.330.290.320.460.540.298.291.401.291.491.321.530.470.520.710.550.380.420.260.410.400.800.350.740.821.152.080.450.400.430.36

10.1510.1410.141.120.480.860.720.520.580.38

12.7010.1710.1910.1710.1610.1810.171.702.392.583.90

10.40

Type2N38192538202N38662N39042N39052N39062540362N41232N41242541262N42362N42892N42922N44162N44442549212N50422 N50602550612N50642550862550872N52082N52942552962N52982N53222 N54492N54572554582N54592554942N54962 N6027

Price (10.4710.721.08

10.2010.2010.200.94

10.1710.1710.172.20

10.3210.320.861.900.801.65

10.2810.3010.6310.4910.50t0.590.660.680.711.16

10.1810.4610.4010.580.851.050.55

256107 0.712N6122 0.602N6178 1.07256180 1.39256211 2.742583378P 4.282SC458C 0.782SC643A 2.252SC930D 1.502SC1061 1.452SC1172Y 3.552S0234 1.483N128 1.8040250 0.984025140327403614036240410404294053040595406034063640654

1.140.670.480.600.940.880.791.391.131.250.89

LINEAR IC'sType Price (f)BRCI 330 10.93CA81OQM 2.44CA3005 1.85CA3012 1.45CA3014 2.23CA3018 0.71CA3020 1.89CA3028A 0.80CA3028B 1.09CA3045 3.75CA3046 0.70CA3065 11.74CA3068 1.90CA3130S 1.67FCH161 12.40FCJ101 13.32LM309K 1.98LM38ON 1.30LM1303N 3.08MC1307P 11.82MC131OP 11.94MC1312P 2.34MC1327P 11.88MC1330P 10.93MC1350P 11.22MC1351P 11.42MC1352P 11.42MC1357P 12.92MC1358P 12.30MC1458G 1.43MC1496L 1.16MC3051P 0.58MFC400B 0.85MFC4060A 0.98MFC6040 1.11MIC1P 2.58ML231 13.57ML232 13.57NE555 0.72NE556 1.34NE566 1.96SAA1024 15.70SAA1025 110.35SAS560 12.01SAS570 12.01SC9503P 11.40SC9504P 11.38SL414A 1.91SL432A 2.52SL450 5.10SL901B 14.20SL9178 16.80SL918A t4.95SN72440N 12.21SN76001N 11.87SN76003N 2.22

Type Price I LISN76008KE 1.66SN76013N 1.68SN76013ND 1.40SN76018KE 1.65SN76023N 1.56SN76023ND 1.40SN76033N 2.22SN76110N 1.20SN76115N 1.82SN76116N 1.78SN76131N 1.32SN76226N 12.00SN70227N 11.81SN76228N 1.80SN76502N 11.92SN76530P 10.97SN76533N 11.38SN76544N 11.85SN76546N 11.85SN76570N 11.81SN76620AN

10.99SN76650N 11.48SN76660N 10.84SN76666N 10.98TA7073P 13.51TAA263 12.20TAA300 12.20TAA320 1.10TAA350A t2.48TAA370A 3.18TAA435 11 .70TAA450 t3.39TAA521 1.10TAA522 2.09TAA550 0.46TAA560 1.93TAA570 12.30TAA61 1 A 1.20TAA611B 1.85TAA621AXI 2.43TAA6300 3.91TAA6305 4.18TAA661A 1.76TAA661B 1.76TAA700 12.80TAA840 13.38TAA861A 0.95TAA930A 1.43TAA930B 1.43TAA960 12.25744970 12.48TA0100 1268

(Filter) 0.98T8A120A 10.90TBA120S 10.99TBA120SA t1.02TBA231 1.32

Type PriceTBA240A 13.98TBA281 12.07TBA395 12.58TBA396 t2.40TBA400 12.20TBA480G 11.84TBA500 12.21TBA510 12.21TBA520P 13.40TBA530 12.24TBA540 12.88TBA550 13.13TBA560C 13.18TBA570 11.29TBA611B 2.68TBA641 2.55TBA641Al2 2.65TBA641811 2.90TBA651 t2.42TBA673 12.19TBA700 12.50TBA720AQ t2.38TBA720Q 12.38TBA750 12.18TBA800 2.05TBA810AS 2.00TBA920 13.80TBA940 13.52TBA950TBA990TCA270ATCA280ATCA290ATCA420ATCA440TCA640TCA650TCA660TCA730TCA740TCA750TCA760TCA820TDA440TDA1003TDAI004TDA1005TDA1022TDA1024TDA1034TDA2610TDA2640ZN414

12.7812.90t3.551.433.461.981.672.762.762.763.543.042.531.523.29

14.361.522.733.046.890.971.982 862.861.45

Indicates Qversion is alsoavailable.

DIODESType Price (f)AA113 0.17AA119 0.21AA129 0.28AA143 0.18AAY30 0.28AA213AAZ15AA217AYI 02BA100BA102BA110BA111BA115BA116BA12IBA129BA145BA148BA154BA155BA156BA157BAI 58BA159BA16484170BA18284201BA202BA203BA216BA2198424384317BA3I 8BAV10BAV21BAW62BAXI 3BAXI 6BAXI 7BAY72881048881058BB105G86100BY100BY103

0.420.350.282.550.240.360.800.700.170.560.860.450.190.190.060.170.120.250.280.400.140.180.270.130.140.140.080.110.450.060.070.100.180.080.070.100.190.160.520.330.300.400.350.35

Type Price (f)BY114 0.60BY118 1.10BY126 0.20BY127 0.24BY133 0.35BY140 1.40BYI 64 0.75BY176 2.80BYI 79 0.83BYI 82 1.14BY184 0.44BY189 5.30BY190 4.90BY206 0.26BY238 0.25BYX10 0.30BYX38/600 0.70BYX70/500 0.5317744 0.08117210 0.63171827 0.80MCR101 0.43MR854 1.10045 0.880A10 0.580A47 0.200481 0.190A90 0.130A91 0.150A95 0.200A260 0.1104202 0.130A210 0.89TIL209 0.16TIL211 0.20TV20 2.25N914 0.06N916 0.09N4001 0.06N4002 0.07N4003 0.08N4004 0.08N4005 0.09N4006 0.10N4007 0.1255400 0.15N5401 0.17N5402 0.20S920 0.09S921 0.11

VDR's, etc. (I)Type Price ( flE295ZZ

/01 0.28/02 0.28

E298CD/A258 0.25

E298ED/A258 0.22/A260 0.22/A262 0.22/A265 0.22/P268 0.22

E298ZZ/05 0.25/06 0.22

E299DD/P116-P354 all 0.23

E299DH/P230 0.72R53 1.75

VA1015 0.92VA1026 0.79VA1033/34/313/

39/40/53all 0.20

VA1055s/56s/66s/67s

all 0.23VA1074 0.20VA1077 0.31VA1091 0.291096/97/98

all 0.20VA1103 0.32VAI 104 0.46VAI108/09/10/

11/12 0110.24VA8650 1.202322 554

02221 0.592322 662

98003 0.88

VALVES (I)Type Price (flDY86/87 0.75DY802 0.75ECC81 0.78ECC82 0.95ECC83 0.78ECH81 0.83ECL80 0.82EF80 0.60EF183 0.75EF184 0.75EH90 0.94EL34 1.68EY51 1.20EY86/87 0.67PCC84 0.81PCC85 0.79PCC89 0.74PCC189 0.94PCF80 1.20PCF86 0.87PCF200 2.32PCF801 0.74PCF802 1.20PCF805 3.37PCF808 2.00PCL82 0.93PCL83 1.12PCL84 0 65PCL86 0.74PCL805/85 1.00PD500 3.75PFL200 1.40PL36 1.20PL81 0.94PL84 0.79PL504 1.05PL508 1.86PL509 3.10PL519 3.10PL802 3.25PY81/P810 0.60

RESISTORS mix. of minktivm ofCarbon Film OM) It) /0 of one lOpoa of any value:

4W 5.80-330k0161214W 100-10M01624)1W 100-10M01E12)

2W 100-10Ni/1E6)

Wirwound 15%124W 0.220-27004W 1.00-10k07W 1.00-22k0

11W 1.00-22k017W 1.00-22k0Vertical mounting pillars

Ea value 5Opc 100pc3p 25p 954 C1.493p 25p 91p £1.495p 45p [1.95 3.409p Op 0.80 C8.40

18p22p24p28p33p

3p

500pc08.40t5.40

£15.25£26.80

Presets It)0 1W (Vertical and Horizontal)100, 220, 4700. 1,2 2,4 7, 10.22,47,100,220, 470k0, 1.2 5, 5M0

all 14p each0.2W (Vertical and Horizontal)Values as 0.1W all 14p ..eh

FUSES (all packs of 10)20mm Time Delay (SEAS)4OmA £3.6850, 63mA £2.55100mA £1.86160, 200, 250mA £1.44315, 500, 800mA, 1. 1.25,1 6. 2, 2 5, 3.15, SA

all £1.19

20mm quick -blow (BULB)100mA 68p200. 250. 315, 500, 630,800mA, 1, 1.25, 1.6, 2, 2.5,3.15. 5A all 56p2A circuit breakers

metal £1.52plastic E1.48

LABG EAR (Details of full range on request)COLOURTEXT ADAPTOR 7026Full facility Colourtext decoder to place between aerial andreceiver. All you would expect of a quality ready-made unit.Leaflet on request. 1E340.20

COLOUR BAR GENERATORCM6052/DB. VHF/UHF gives standard 8 band colour bars

variable tuning + front panel on/off switch + sync triggeroutput blank raster - red raster crosshatch + greyscalestepwedge colour bar centre cross , dot patterncentre dot. £182.25

ZENER DIODES400mW plastic 3.0-33V 14p each1/1.3W plastic 3.3-180V 18p each1.5W flange 4.7-75V £1.08 each2.5W plastic 7.5-75V 67p each20W stud 7.5-75V 92p each75W stud 7.5-75V £6.88 each

BRIDGESRating Price (£) Rating Price If)13A 50V 0.27 2A 100V 0.38

100V 0.28 200V 0.40200V 0.32 400V 0.47400V 0.40 600V 0.53600V 0.50 800V 0.80800V 0.58 1000V 0.87

3A 100V 0.52 6A 100V 0.66200V 0.55 200V 0.68400V 0.81 400V 0.74600V 0.87 600V 0.80800V 0.80 800V 0.86

1000V 1.20 1000V 0.951 OA and 25A ranges also stocked.

AMPLIFIERS it)CM6001/PU Power unit for those marked

below £9.42CM6017 Set -back, battery op., single

u.h.f. group £9.21CM6019/VVB Masthead, wideband u.h.f.,

with companion CM6020power unit £14.69

CM6030/WB Masthead, ultra widebandch. 1-68 £17.88

CM6040/WB Masthead, wideband u.h.f. £17.88CM6051. Masthead pre -amp, single

group u.h.f. £9.42Please state which group required, if appropriate.

CAPACITORSMetallised Paper If)2n2F 1500V DC 60p2n2F 600V AC 24p3n6F 1700V DC 60p4n7F 1500V DC 80P10nF 1000V DC 22p

Reversible Elecoolytics (1)10nF 500V AC 80p 33V 6pF42p 50V 25pF 53p15nF 300V AC 30p 50V 4pF 30p 32pF 55p22nF 300V AC 32p 6pF 30p 50pF 58p

100nF 1000V DC 20p 8pF 34p 150V 4pF 60p470n F 1000V DC 60p 12pF 36p 250V 1pF 83p

)6pF 38p 2p2F 86p

CONVERGENCEPOTENTIOMETERS5, 7, 10, 15, 20, 50, 100,200,500Q 138p eachSpindles for

above 5p each

VHF to UHF CONVERTER CM6022/RA. 'Televerta" for DX-ing or uhf receiver use on relay systems, Eire etc. tf24.40

P. & P. UK: £0.12 per order. Overseas: At cost.Please add VAT at 8% and 12196 on items marked1.It is only possible to show part of our range here. Ourcatalogue (30p refundable) shows Service Aids, 7400series, CMOS, op amps, SCRs etc., hardware,capacitors, special TV items and many more transistors,diodes, i.c.'s and valves.Giro A/c 23 532 400. A/c facilities available

EAST CORNWALLCOMPONENTS

CALLINGTON - CORNWALLPL17 7DW

TEL: CALLINGTON (0579312637. TELEX: 35544(OFFICE OPEN 6.30-5.00 MON-FR1)

452 TELEVISION JULY 1978

EDITORJohn A. Reddihough

ASSISTANT EDITORLuke Theodossiou

ART EDITORRoy Palmer

ADVERTS MANAGERRoy Smith 01-261 6671

CLASSIFIED ADVERTSColin R. Brown 01-261 5762

CORRECTIONThe power supply pin connec-tions for the 7490 i.c. were givenincorrectly on page 415 of theJune issue in the sync pulsegenerator article. Pin 10 shouldbe connected to chassis, with the5V supply to pin 5.

7T BERNWho repairs what?The TV cowboys letter we published in our April issue produced a considerableresponse from readers - as we thought it would, the subject being one on whichmany readers hold strong views. It bears upon difficult problems however. At oneextreme, there's the view that only those licensed to do so should be allowed tooffer the public a TV repair service. This approach has been adopted in one or twocountries, and there are precedents here. If you offer credit facilities, you nowhave to be licensed; if you offer driving instruction for payment you likewise haveto have a licence. But the British public does not take too kindly to this sort ofthing. If it did, we would all cheerfully carry identity cards and have our fingerprints stored away somewhere, all of which would undoubtedly help in the battleagainst crime. The public won't have it however. And, returning to the business ofgetting TV sets repaired, it's unlikely that it would be happy about being told howto go about this - though it's ready enough to complain if it feels it's beendone. There's also the practical problem of supervising any "authorised" system.Would the police be expected to check on shops and advertisers in local papers?Would you be committing an offence if you got a friend to "have a look at" yourtelly? No, this just doesn't look like being on. Nor is the analogy with credit ordriving instruction particularly pertinent. The former brings us into the realms ofbanking and public funds, the latter could involve injury - though so could afaulty TV set, while you can give driving instruction to your friends provided theydon't pay. It's a question of where to draw the line, never an easy thing to decide.Usually someone eventually sets up an official enquiry, in the fullness of time alengthy report is produced, then the argument starts in earnest!

One can appreciate why some of those in the trade feel that steps should betaken to give the public greater protection. If you've gone to the trouble of takingthe appropriate courses, gaining your certificates, and ensuring that you eitherhave or have access to adequate equipment and spares, it's a bit galling to findsome dabbler having a go on the side and undercutting the cost of providing aprofessional service. It's especially galling if you get only the awkward, timeconsuming faults or the set that's been well and truly got at, while the localhandyman or part timer creams off the simple jobs on a cash only basis.

To go to the other extreme, there's the argument about freedom of choice. Justwhy shouldn't you go to whomsoever you please? Why should anyone lay downrules as to how you should go about as simple a matter as having your tellyrepaired?

These are the extremes, and there's a wide range of possible viewpoints inbetween. We hesitate advocating anything very specific ourselves, and wouldprefer to let readers, who after all often have greater experience of dealing with thepublic in such matters, air their views. At the end of the day however it's a matterof trying to ensure that the public gets a fair deal. It's in everyone's interest thatservicing is carried out efficiently, safely and at a reasonable cost. So far asretailers are concerned, the RETRA sets guidelines and adjudicates where adispute is taken to it. That's fair and is the sort of thing traditionally done in manyother fields in the UK - it's called self -policing.

Could such an approach be extended? It seems unlikely. How do you involvethose who operate on a part time basis? You can't stop them, and if you could dowe really want to? As several letters have pointed out, many an enthusiast findswork building up because the service provided by local established shops has beenfound wanting.

In this age of consumer protection you might think that protecting the publicand restricting the often dangerous efforts of the bodger would be part of ourconsumer legislation. In practice, in a field as diffuse and diverse as repairingbroken down tellys it seems unlikely that anything much can be done to ensurehigher standards to the public. The problem may well simply fade away with timehowever: the more complex TV sets become, the less likely they are to appeal tothe dabbler when defective.

TELEVISION JULY 1978 453

Teleto icsCALL FOR INDUSTRY CUTBACKThe recently published progress report of the NationalEconomic Development Council's sector working party onthe consumer electronics and components industryrecommends that the size of the industry needs to beurgently cut by something of the order of 20-30 per cent,with the government considering support for the creation ofalternative jobs. The report also recommends that thestrongest possible diplomatic support should be given to theindustry's demands for cuts in imports - particularly in TVand audio products, not only from Japan but also fromother "far eastern bloc sources".

The report says that the industry's fixed assets are beingused at only about 50 per cent of their potential. Our reporton TV plant closures and other steps last month suggeststhat the industry is already in the process of reducingcapacity, while the latest BREMA figures show that the percentage of the TV set market taken by imports has alreadybeen reduced slightly compared with last year. The situationnevertheless needs to be carefully watched. There's thepossibility of a flood of Japanese video equipment in theoffing, while promises by the Japanese to limit unofficiallytheir exports in various fields and reduce their mammothtrade surpluses have on too many occasions come tonothing. There are good reasons for this: the whole growthof the Japanese economy has been based on large scaleexports of consumer products, and to change the balance ofthe Japanese economy is not something that can be doneovernight. The trouble is that one doubts whether the will todo so is there: the giant Japanese corporations are probablybeyond any effective control.

Returning to the NEDC report, the following targets forthe industry are suggested: reducing import penetration to37 per cent by 1980 and to 35 per cent by 1984, withexports increased from their 1975 level of £78 millions to£150 millions by 1980 and £280 millions by 1984. It mayappear ominous that the year 1984 was chosen as the targetdate, whilst the realism of pulling figures that far ahead outof the hat is open to question. It would be nice to be right,but other countries will be aiming for the same ends,seemingly against a background of stagnant world trade.The one hopeful thing is the signs that the industry hasalready set about achieving a better performance and isholding its share of the market. The main presentweaknesses are on the audio and radio side, while for thefuture one's concern must be as to whether the industry willbe in a position to take advantage of technical developmentsand breakthroughs.

In a particularly interesting passage the NEDC workingparty complains that its attempts to work out a possibleindustrial strategy were "considerably handicapped" by theefforts it had to put into opposing the Hitachi project for anadditional TV plant in the UK. It seems to have beensingularly unimpressed by assurances that this would usemainly UK produced components, and estimates that hadthe plan gone ahead the net loss of jobs could have reached5,000, accompanied by a substantial worsening in theindustry's trade balance.

The working party feels that significant progress was

made last year, and suggests that the industry can increaseits share of the Western European markets where it benefitsfrom a significant cost advantage. On quality and reliabilitythe report comments that further progress has been made ineliminating the gap between Japanese and British products,but points out that the fragmented nature of the industry(there are eleven companies making colour TV sets in theUK) means that the companies do not have the scope for asustained, aggressive, volume -based export programme.

According to the report imports rose from 8 per cent in1970 to 41 per cent in 1976, while exports improved from 8per cent of output to 23 per cent. With the decline in thehome market from the cataclysmic boom of 1973, and theimproved exports, the industry's balance of trade deficitnarrowed from £219 millions in 1973 to £131 millions in1976.

Employment in the industry has fallen from a peak of70,000 in 1973 to 49,000. Rationalisation andmodernisation will cut jobs further in the short term, but it'shoped that a planned contraction will provide the basis foremployment growth in the medium to long term.

COLOUR PORTABLESOne of the main features of this year's trade shows will bethe introduction in many well known ranges of receivers ofsmall -screen - 14 or 16in. - colour sets. Bush started thetrend with their 14in. model BC6004, mentioned in theFebruary Teletopics: more recently Philips followed up withtheir 14in. Model 825. The latter now makes its appearancein the Pye range as Model CT6225, while a 16in. model(MC6124) is to be added to the Murphy range. ITT are alsopoised to introduce a 16in. model.

One of the most interesting colour portables however isthe new Ferguson 14in. Model 3787 "Movie Star", sincethis is designed for both mains and battery operation. Abattery adaptor, type TA75, which fits inside the cabinet,converts the set for operation from a 12 or 24V battery. Theset weighs 32+lb, and the attractive black and silver cabinetis fitted with two recessed carrying grips.

Other interesting news from Thorn is the introduction oftwo new large -screen monochrome sets, the 20in. Model3850 and 24in. Model 3852.

BRIGHTER COLOUR CRTsIncreasing the light output from colour tubes is one of thecurrent development trends. Late last year ITT announcedthat a new version of their Model CC781 would be fittedwith a new ITT tube - a version of the 20AX - giving 70per cent greater light output. Mullard have now announceda new version of their 20AX tube called the Hi-Bri whichagain offers a 70 per cent increase in brightness, with noloss of contrast. Under normal viewing conditions whereincreased light output is not required the viewer gains fromthe improved resolution and the reduction in powerconsumption resulting from the lower beam currentrequired. The extra brightness also makes it simpler todesign an effective control circuit to optimise the brightnessunder different ambient lighting conditions.

454 TELEVISION JULY 1978

The basic approach to obtaining increased light outputfrom the 20AX tube has been to widen the slots in theshadowmask, thereby increasing its transmission factor.The Hi-Bri tube's shadowmask transmission factor is in fact30 per cent greater than that of a standard 20AX shadow -mask. The contrast range is maintained by increasing thetransmission factor of the glass faceplate by the sameamount. These changes give 70 per cent greater lightoutput, with the contrast range increased by 7 per cent.Increasing the shadowmask's transmission calls for a highdegree of precision in order to retain the same purity, sincethe increased area of the phosphor stripes activated by thebeams reduces the effective guard band between stripes.

Meanwhile, Thorn have announced that improved c.r.t.swith higher light transmission glass and pigmentedphosphors to improve the contrast range are being used onthe latest versions of their 8000 and 9000 chassis. The tubesare types A44 -272X and A51 -163X respectively. Thistechnique was described on page 530 of our August issuelast year, when we reported on a visit to Thorn's Enfield TVplant. The improved type A67 -128X tube is being used in26in. models.

STATION OPENINGThe Chagford, Devon relay station is now in operation onchannels 21 (BBC -1), 24 (Westward Television) and 27(BBC -2). A vertically polarised group A receiving aerialshould be used.

MORE VCRsThorn are to introduce a VCR to the JVC VHS standard atthe forthcoming 1978 trade shows. It will be known as theVideostar and will give up to three hours' continuous recordor playback. Distribution will be via appointed dealers, andsales and product training sessions will be available attwenty six different venues throughout the country.

A new Grundig VCR -only factory is nearing completionat Nuremburg, the aim being to counter the increasingcompetition from Japanese VCRs in the European market.Their new Model SVR4404 will have a four-hour capabilityand is to be shown at the forthcoming trade shows. Grundigplan to produce 10,000 of these VCRs by the end of theyear.

SOLID-STATE VALVE REPLACEMENTSAs the days when valves were used in current productionTV sets recede into the past so the price of replacementvalves escalates - if indeed you can get them. We had thelatter experience ourselves recently when we approachedour local supplier for a new PL83 - the video outputpentode that was the standard device before the PFL200came along. "Not in the list any more old chap" said he.We found a source shortly after, but it set us thinking. Itseems that the rental organisations, which still have largenumbers of hybrid sets (our set wasn't even that!) in use,are much concerned about the cost of replacement valvesto keep their sets going. One rather notorious valve (thoughit does lead a hard life) is the PL802 luminance output101871

10M

2

(Control grid)

4

TrlMPSA42

47p

(Heater) 3047

(Heater)5

lk8

Tr2BF459

7

(Anode)

(Cathode)

0

Fig. 1: A solid-state PL802: resistors 0.33W unless other-wise indicated; 47pF capacitor ceramic plate.

7W

pentode, and one or two solid-state equivalents are appear-ing. Fig. 1 shows a typical example. An emitter -follower isrequired to provide a high -impedance input, and a BF459provides the high -voltage swings to drive the c.r.t. cathodes.A 7W, 47Q resistor is included to provide heater line con-tinuity, and the whole thing is arranged as a plug-inreplacement. Neat.

TV SOUND CHANNEL ICThere have been several combined intercarrier soundchannel/audio amplifier/output i.c.s announced by thevarious i.c. manufacturers, but very few seem to have beenadopted so far by setmakers. The only model we can thinkof in a UK range using such an i.c. is the German -producedBush Model BC6004 small -screen colour transportablewhich features a TDA1035 6MHz sound/audio i.c. MaybeRCA will have more success with their newly introducedCA1190GQ, a version of their industrial type TDA1190Z,differing primarily in its provision for external feedbackcomponents and the use of a higher value volume control.The i.c. consists of a multistage i.f. amplifier/limiter section,f.m. demodulator, regulated power supply, d.c. volumecontrol and an audio amplifier designed to drive an 8, 16 or32Q speaker. The nominal power output is 3W and thedevice will operate at supply voltages over the range 9-28V.Typical performance figures are: quiescent current 25mA,5kHz deviation sensitivity 1W, 3dB limiting sensitivity50µV and a.m. rejection 50dB. The electronic volumecontrol incorporates improved taper and single -wire control.The CA1190GQ is supplied in a hermetic gold -chip 16 -leadQUIL plastic package with integral heatsink for printed -board mounting.

VIEWDATA AND TV USERA new quarterly journal entitled Viewdata and TV User isto be launched by IPC Electrical -Electronic Press, aimed at'all those interested in the expanding use of the TV screen asa comprehensive information service. The first issue willfollow on the start of the trial Viewdata service thissummer. In addition to feature articles and latest news andproduct information, each issue will contain an updatedPrestel (as the PO has now decided to call its Viewdatasystem) directory for users of the service.

TV AERIAL/GAMES COMBINERSA TV set's aerial input connector is a fairly delicatearrangement not intended for constant plugging in andunplugging. Generations of service engineers know aboutno or poor results due to a fracture or break, and theproblem has increased with the popularity of TV games.The aerial lead can also be damaged. The answer of courseis an external combiner for the aerial and TV games inputs,with a switch for selection of either input. Qualitycomponents are required however if signal deterioration isto be avoided.

We mentioned one such unit, available from AdamImports Ltd., Harrogate, in the March Teletopics. Twomore units have since been introduced, one by VoltmaceLtd., Knap Close, Letchworth, Herts and the other, typeCM7042, by Labgear. The insertion loss with the CM7042is less than 2dB for the selected input and the isolationbetween the two inputs 50dB - good isolation is essential toavoid the TV games signal being radiated via the aerial.Labgear suggest three other uses: for combining VCR andaerial inputs; for combining two aerials where ghostingprevents the use of inductive combiners; and, in reverse, toswitch a single input between two receivers.

TELEVISION JULY 1978 455

Hot Pyes

TIME after time we've noticed that if you get one awkwardone in of one type you're bound to get half a dozen of themin a row. A little while ago we were plagued with Thorn3500 chassis, one after the other, all awkward, nothingeasy. Then came the Philips G8s, one after the other againuntil we cried out in anguish, enough, enough, let's have anend to it. The other day though it was the turn of the Pyegroup hybrid models - 691, 693 and 697 chassis, Pyes,Ekcos, Invictas, etc. Normally these sets are no trouble tous at all: one can usually put a couple of items in one coatpocket, a couple of tools in another and carry a solderingiron etc. to the scene of the crime in full knowledge that ifthe customer has described the symptoms correctly the jobwill be done in minutes. You know the sort of thing: picturewent off, sound still o.k., a smell of burning (or saw smoke)and switched off (or the set went off completely as the fusefailed). The one or two items in this case would be a 1001c521W resistor, an 0.1µF 1kV capacitor and the usual fusesnormally in the trouser pockets anyway.

The Stock TroublesAvid readers will have no trouble in identifying this

common fault. The 0.1µF capacitor (C224) decouples theboost line feed to the c.r.t. first anode presets, coming viathe 1001(52 resistor (R227). The capacitor shorts, theresistor cooks and the fault then becomes the same as if the0.47µF boost capacitor has shorted, the difference beinggiven in the description, i.e. smoke or a smell of burningwhich doesn't occur when the boost capacitor goes short-circuit because the PY500 immediately passes excesscurrent and the fuse fails.

For the benefit of less avid readers, or if the symptomshave not first been properly described, the way to tackle thecondition is as follows. Check the fuse. Connect anohmmeter from the top cap of the PY500 (or PL509) tochassis. If there is a low reading (should be about 1MQ,give or take a few hundred thou'sand - let's not be meanabout this, say the needle moves on the x 1 scale or morelikely swings over to give a definite reading) there is a shorton the boost line. There are two likely conditions (lots ofothers, but two likely). One is that the 0.47µF boostcapacitor C218 on the line output transformer assemblyhas shorted, the other that R227 has become a charredimage of its former self due to C224 shorting, the 100k52now being more like something under 10052 (hence theunspecified movement or deflection on the low ohms range).The clue is in the appearance of the 100kQ resistor. If it'sclean and brightly showing its brown -black -yellow bands,suspect it not. Neither suspect C224 of course. Snip one endof C218 (the fat capacitor) and read again.

Ah, you may say. This is all very well, but where do welook for the 1001a2 resistor, to see if it is feeling poorly? Ah,we reply. It all depends. If the right side section is mainly ametal box, look underneath on a tag panel about half waybetween the PL509 and the PCF802 valve bases, with the0.1,0 capacitor laying along toward the shift controls(early models), or smack in the middle on later models(691). If the right side is occupied by a vertical printed panel

Les Lawry -Johns

(later 697 chassis), note the top centre red box with the fuseinside. Look down the centre about a third of the waydown, just above the transformer, and there it is, with C224leading off to the right. All right?

Unstable SoundWell now, none of this applied to our row of Pyes, and

more's the pity. The first one seemed simple enough to startwith. No valves glowing. Early model, metal box on rightside. Move it out to check the supply line. O.K. CheckPY500 and PL509 heaters. O.K. Move the box unit backbut fail to notice that the rubber sleeve has slipped downfrom the end of the focus unit (the e.h.t. end). Find break inheater circuit on left side colour -difference amplifier panel -crack in track to one of the PCL84 heater pins. Repairtrack. Valves light up. Lovely picture and sound. Sharpcrack as e.h.t. discharges to convergence panel. Picture stillo.k. Sound goes funny. Very slow motorboating, low soundclear, loud sound increases the rate of motorboating tomake the effect garbled.

This could be due to an open -circuit electrolytic in thepower unit or a fault in the audio module, possibly a faultytransistor. Check the easy thing first. Clip a highcapacitance electrolytic across the supply to the module.No improvement. Fault must be in module.

Now the module in these earlier models is a MullardLP1162. The most common complaint is failure of theoutput transistors. This cooks up the 2.2Q resistors whichare connected between the emitters for bias purposes.Replacement is no joke, as we've mentioned before. Rushdown to van and say unkind things to sleeping guard dogwho continues sleeping. Rummage in spares box. Twomodules. One used, one new. Rush up with both. Fit newone. Similar symptoms as before. What now? Don't know.Check this, that and the other. Remove front control panelagain. Remove module again. Fit used one. Lovely clearsound. I hate modules. Make sure e.h.t. cannot dischargeagain. Carefully mark modules u/s.

No SignalsCarry on to next set not too far away. Ekco with the 697

chassis. Varicap tuner. Raster and noise on screen, just as ifaerial is disconnected. Aerial is disconnected. Plug in aerial.No change. Check tuning. Suspect loss of h.t. to the two9.1kQ resistors on top of the tuning panel (Fig. 1). H.T.present, and just over 30V at the TAA550 zener. Nowwhat?

Remove tuner panel and check voltages. A.G.C. o.k. atA. +12V at B, nothing at C. This is where the tuningvoltage should be. Check again and hold tuner steady.Tuning voltage o.k. at around 10V and lots more noise.Reach round and tune in sound and vision. I.F. unit on oneknee, tuner on other, very uncomfortable. Let go of tuner.No tuning voltage, no sound only hiss. Move legs. Sharppoint on if. panel penetrates trousers. Has to be 200V h.t.Move more quickly and wish I were dog in van. Examinetuner more carefully. Intermittent short to earth from tuner

456 TELEVISION JULY 1978

voltage point C when tuner is moved. Take off cover andfind tiny piece of wire which had no right to be there.

This was a bit of a relief actually, because we've had ourfair share of trouble with varicap tuners of various types.It's usually a faulty transistor or wires touching (just) theside wall, but we had one where the tuning voltage was lostdue to a coil inside the screened compartment intermittentlytouching the wall of the compartment (lid soldered on).

Intermittent BlueSo having restored normal signals and replaced the tuner

and i.f. panel we thought we'd finished. No such luck."While you're here," said the gaunt Mr. Moneypenny,"perhaps you'll clear a minor thing. The blue keeps going."I like this "minor" business. It implies that it won't take amoment, any fool could do it if he wasn't so busy, and ofcourse it won't be worth charging for.

Anyway, the blue did drop out as we watched the testcard, and promptly dropped back in again. We diagnosed apoor contact under the blue PCL84 on the CDA panel.Inverting this, we were surprised to find hardly any sign ofdeterioration. All was bright and clean. No poor solder, nocracks, nothing. Tapping around above the panel producedblue drop out all around the area however. More gentledisturbance finally seemed to cast suspicion on RV27, theB-Y drive control which is part of the blue preamplifiertransistor VT3 l's load, as the collector voltage of thistransistor came and went as the preset was moved one wayand then the other. Fitting another preset seemed to clearthe condition, but on checking the control later nothingseemed to be wrong with it at all.

Dealing with Weak Line HoldBack on the bench sat yet another specimen, this time a

Dynatron set resplendent with a black front control panelwith lots of little chrome knobs, but still a Pye at heart.Again the 697 chassis (glad of this really, because we're stillnot completely at home with the later solid-state 725 etc.with vertical swing panels). The note read "loses line holdafter one hour, also poor brightness and colour." Coward tothe last, we tackled the poor colour and brightness first. Anew PL802 worked wonders for the brightness anddefinition. Soldering suspect joints under the panel andimproving the earth contacts to the rear edge clips seemedto clear up the colour.

Now for the line hold. Always tricky on these sets, purelybecause of the vertical right side panel. The PCF802 line

Channelswitch

Tuning4---°.p.;entiometer

Feed viaAFC circuiton IF panel

Tuner

0-28V

AGC 12V

190V HT via IF panel

12V

0.1 005

47

9k1

9k1

30V

TAA550 .002

IF output

102231

Fig. 1: Varicap tuner supplies, Pye 693/697 chassis. Thereare six channel selector switches/tuning potentiometers.

oscillator, line hold control etc. are at the bottom and aremost inaccessible. So we don't use normal methods of faulttracing on these sets when such line troubles raise their uglyheads.

Remove the side and top edge connectors, partlywithdrawing the unit. Remove the cover of the line outputtransformer and the clip earth connectors. Remove thefront PK headed 4BA screw which secures the e.h.t. tripler.Lower the panel. Components can now be seen. First checkthe 47kS2 flywheel sync circuit flyback pulse integratingresistor R203. If it looks discoloured or reads less than47k52 on the meter, change it. If it's much less than 471E52,check the discriminator diodes D40 and D41 which cansuffer if R203 goes low. Remove one end of R210 (in serieswith the line hold control) and check its value (100k52). Ifmuch less than 100kQ, replace it. Even if it's not at faultnow it soon will be and can cause other troubles. Thencheck the large 16µF electrolytic and the smaller 1µF and4µF ones. These are C215, C213 and C210 respectively, inthe line oscillator circuit. If these checks are inconclusive,change the PCF802 and the feedback capacitor C211(320pF). This completes the normal checks.

Swing up the panel, refit the tripler screw, line outputtransformer cover, not forgetting the grommets at eitherend, and the earthing clips, especially that of the focus unit.Replace the edge connectors and refit the unit. If theconvergence is wrong or there's something else not working,recheck the edge connectors. This method of attack hasproved its worth over and over again. Indeed, after this theDynatron dyned very well.

ExplosionsWe have always had difficulty in identifying which Dawe

brother is which. Jack Dawe had bought a 26in. Invicta setfrom us some four years ago (697 chassis), whilst his twin,Oven, had more recently (about two years) bought a 20in.Thorn set (9000 chassis). We had not heard a word fromeither by way of trouble, which is not bad when you thinkof it, although we have had a drink with them from time totime.

Anyway, in walked Mr. Dawe. "Hallo Oven," we greetedhim.

"I'm Jack" he corrected me. "Where's the complaintsdepartment? That rotten set you sold me's gone wrong. Ibought it only four years ago. Frightened the life out of ourdog when it went bang. He hasn't been the same since. Andthere was a flash on the wall at the back, or so the wife says.I wasn't looking at it at the time myself."

"How's the wife Jack?" I enquired. "Shelagh isn't it?Lovely girl! Went bang eh? I wonder why?"

"I'm on my way home now," said Jack. "You coming?""Rightho Jack, I'll follow you up just as soon as I've put

a new mains dropper in this brand new set that I've justunpacked."

So off we went up the hill. Pity his wife's name wasn'tJill, but we mustn't invent names just for effect, must we?

When we got there the poodle was running round incircles, apparently chasing his tail.

"Been doing that ever since the set went bang" said Jack."Probably checking up to see that he's still all there" I

suggested helpfully, being an expert on dogs.Taking the back off the Invicta we were not surprised to

find a nasty mess on the top centre of the right side verticalpanel. The mains input is taken directly to the 2.5A fuse,with tracks leading to the edge connectors which lead backto the on/off switch. The supply then comes back again tothe panel to the rectifiers etc. This means that the supply

TELEVISION JULY 1978 457

fuse and its connections are alive when the set is af, apoint well worth bearing in mind.

When there's been a minor explosion, it's difficult t sayexactly what the chain of events were. There's some oltencopper and a blackened area. The idea is to clean Up thepanel, accepting the fact that there's been conduction acrossthe panel between the tracks, the cause of the troubl in thefirst place rather than the failure of a component. Firstestablish which tracks did which job (when they were there)and carefully wire up as neatly as possibly, cutting awayany remaining sections of conductive panel. Someconfusion is possible, so the original circuitry must be keptclearly in mind.

There's another and very important factor. Some longthin tracks run down from the top edge connectors, near thearea likely to have been damaged. Although they may havebeen intact at the time of the original trouble, subsequenthandling of the panel may have extended any fie cracksfarther across the paxolin, fracturing these tracks. This canlead for example to field collapse due to the 20V s pply tothe height control suddenly being lost. Careful ex inationcan save an awful lot of trouble later.

Having patched the patient up nicely, the set was triedout. Picture rather dark at maximum brilliance. it newPL802. Plenty of brilliance. Convergence had w*rideredover the years, but responded to a few minor adjustments.All in all, not bad for four years' service.

Incidentally, the audio module is replaced by an i.c. onsome of these 697 chassis, and there's a separate 1'N4002diode to supply the i.c. instead of the supply being derivedfrom the bridge rectifier.

A further note may be necessary. We've outlined whathappens when there's a breakdown of the panel insulationitself. This condition should not be confused with the typeof blow out that occurs when the mains filter capacitor,wired across the on/off switch, goes short-circuit. Thisshatters the fuse of course, but can also damage the printbeneath, discolouring a small area of the panel. If the panelitself isn't damaged but the tracks are, check the capacitorwhich will almost certainly be found shorted.

The next job was to seat the poodle in front of the set sothat it could see that it wasn't going to go bang again. Beingsatisfied on this point, it no longer chased its tail orwhatever it was. With the poodle straightened out wethought that a quiet five minutes would be in order. Itwasn't.

No Raster

A Pye 691 was apparently no longer entertaining itselderly owner. Off we went armed to the teeth, to wrestlewith the final electronic cock up of the day. We won't boreyou with the old girl: suffice it to say that she didn't stopnattering from the time we entered to the time we exited.The set however was a different matter.

The fuse had failed and there was a short from the topcap of the PY500 to chassis. Oh well we thought (as best wecould against the old girl's incessant chatter), back to theold routine.

Turn up the unit to have a look at the resistors. Weexpected R227 (1001d2) to be charred - as mentionedearlier. It wasn't. Or rather they weren't. In fact the 1001d2resistor had been replaced by two 56E2 resistors in series,and these were obviously in the best of health. Lookingaround however we found the 1001(52 resistor (R210) to theline hold control burnt out instead. This made the lookunder the unit worthwhile after all.

Now whilst this could affect the h.t. supply to the line

oscillator, it wouldn't explain the boost line short which wefoolishly attributed to the 0.47µF boost capacitor on theline output transformer. Having fitted a new 100E2 resistorto the hold control, we were then stupid enough to removethe side panel of the transformer housing to expose the saidcapacitor, instead of checking something else first. Needlessto say the 0.47µF capacitor proved innocent whendisconnected at one end. Then the penny dropped.

Take out the PY500. No short then present. Heater-cathode short in the PY500 you stupid clot. Why didn't youcheck that first?

Well, if we had we wouldn't have found the duff 100E2resistor to the hold control. All right then, make excuses foryourself, after all it is getting late and the old girl is still onabout her sister who died three years back.

Right then. New PY500, new fuse, no shorts. Switch on,lovely sound, real nice that sound. Wonder why the valvesaren't lighting up? The sound which sounded so nice by theway wasn't really sound, just a nice loud hiss since theaerial was not in. Put the aerial in. No difference.

Wait a minute. Even if the valves were not lighting, that'snothing to do with the sound. It's not a 691! It's got avaricap tuner that needs h.t. dropped to supply the 30V fortuning. Quick check. No h.t. Now the old girl is on abouther school days. Wish she'd stop for a moment so that I canthink. Turn the power unit round. A.C. supply o.k. at oneend of the surge limiter resistor, not at the other end. 5.6Qwirewound. Fit another. Try again. Sound o.k., news readernow competing with old girl.

Right. Why don't the valves light up? PY500 is gettingheater supply and is new. What about the PL509? Open -circuit heater.

Oh dear, where's it all going to end? Fit new PL509.Heaters light. Allow time for set to warm up. Rustle of e.h.t.Can now see news reader. Not bad. Square up all roundand wonder what the sequence of events must have been.Switch set off and wait for lady to stop going on aboutpresent day school standards. At last we manage to get ourbit in and escape. Name on the cheque, Nightingale. Notvery clever and logical was it? We do try to be butconfusion usually sets in toward the end of the afternoon.Getting old.

TV TELETEXTDECODER

TROUBLE -SHOOTING AND REPAIRSERVICE

To assist constructors who may encounter difficultieswith this project, Television Technical Services areoffering a trouble -shooting and repair service for thevarious modules. The charges are as follows: modulator£2; input card £4.50; memory card £3.50; display card£4.50; i.f./data recovery card £4.50 (includingalignment) or. £6 to include published modifications.These charges include the cost of replacing minorcomponents, and return postage. Any expensivereplacement parts needed will be notified toconstructors. Modules should be sent with remittanceand package able to withstand return mailing. Write orphone for a quotation if you wish to send all four boardsfor testing.

Television Technical Services,PO Box 29,Plymouth, Devon. Tel: 0752 813245

458 TELEVISION JULY 1978

TRANSFORMERS

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Pye 691 or 697 Chassis.

Bush CTV 25 Mk. 1 -2 - or 3.Decca CTV 25 Non-Tripler Version.

Philips G.6 Single or Dual (Overwind for thisModel on Exchange Basis Only).

Philips K.70 Underwind Only.

EMO 90°

COMPLETE L.O.P.T.SPhilips G.8, ITT C.V.C.5-9 and Decca Bradford.

Prices for the above Colour L.O.P.T.S andWindings on application.

S.A.E. all enquiries.

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TELEVISION JULY 1978 459

Wideband Signal Preamplifierusing a thick -film integrated circuit

THE present signal preamplifier is based on the SGS/ATESSH221 thick -film integrated circuit, which was selected as amethod of providing a simple yet effective amplifiercovering the v.h.f./u.h.f. television spectrum. The SH221 isreferred to as a "hybrid v.h.f./u.h.f. wideband amplifier" inthe SGS/ATES data sheet, and contains all the active andpassive components required, the only external arrange-ments necessary being the provision of a suitable supplyvoltage plus mounting and interconnections.

The need for such an amplifier became evident when theauthor reviewed a wideband v.h.f./u.h.f. aerial signalpreamplifier of Danish origin in the October 1977 issue.Unfortunately distribution of this amplifier in the UKceased just prior to publication of the review, which resultedin a couple of hundred orders which could not be fulfilled.

The first sample SH221 i.c. we received was notencapsulated (see cover photograph) and all the com-ponents, including the two transistors, could be clearlyseen. They are mounted on one side of the basic substrate.Subsequent versions obtained were coated with a caramelcoloured substance. Mullard have recently introduced asimilar range of hybrid wideband amplifiers, but these havenot been tried out to date.

Pin ConnectionsThe SH221 is conveniently compact and has seven

connection pins. Four of these go to earth, two are forsignal input and output and the final one is for the supplyvoltage. The electrical performance is excellent, thespecification sheet quoting a gain/bandwidth product of

* Components listIC1 SH221D1 BY127C1 0-001pF ceramicC2, 3 220pF 40V electrolyticC4 0.001pF feedthroughC5 470pF ceramicR1 2500 5W, WW

(2200 for 26V supply)RFC 1A VHF chokeSW1 Miniature d.p.d.t. mains switchF1 500mA miniatureNi Mains neonT1 Eagle MT150Tagstrip, diecast box, two coaxial sockets, solder tags,grommet (tailed).

Roger Bunney

17dB ± 1dB over the range 30-900MHz with a typicalnoise figure of 5dB. The supply voltage required is 24V at35mA, with a maximum applied voltage of 28V. Fig. 3shows the gain/bandwidth response at 24V.

PerformanceOn test, the prototype worked immediately with no trace

of instability within the bandwidth - even when runningwith the input unterminated. With a 24V supply the currenttaken was found to be 32mA, slightly lower than specified.In view of the 4V maximum supply voltage margin howeverit was decided to accept slightly reduced gain, erring on theside of safety. An increase of perhaps 2V could beentertained, increasing the current to around the 35mAlevel.

Gain/frequency MeasurementsThe voltage gain was measured at certain spot frequen-

cies (see Table 1), and on the prototype was found tobe generally lower than quoted in the specification,

Internal view of the prototype.

460 TELEVISION JULY 1978

240V AC

IC1224

In

75.n.

Fl

SH12 OA

2 3 5 6

12 DI RI C4RFC

24VSH221

0 ICI

2ZIc C2 C3 C 5

Input Out put--1 1 1 1 1 1 1

7 6 5 4 3 2 1

Fig. 1: Complete circuit left, SH221 pin connections right.

12V

I:RFCit 2pH

680p Out

75.n.

102251

Fig. 2: Test circuit for the SH120A thick -film wideband signalpreamplifier i.c. This version operates at 12V with a currentconsumption of 20mA. The input pin is d.c. isolated internallyby means of a 680pF, 50V capacitor.

22

24

20

16

12

Bo200 400 600

Frequency (MHz)

Fig. 3: Gain/frequency characteristic curve.

12

9

6

3

0

800 1000

0 200 400 600Frequency (MHz)

Fig. 4: Noise/frequency performance.

0Supplyvoltage C4

/it

Input C1°--11

[02261

"T

800

LI

R3 R7

R6 C5 Output

000

L2 L3

R4 R 8

R2 95 _C2 R9 C3

47,

Fig. 5: Internal circuit of the SH221 thick -film widebandsignal preamplifier i.c.

- Input2.3,5,6 - Ground4 - 4247 - Output

doubtless due to the current factor mentioned above. Thisapart, the gain tended to follow the curve shown in the SGSdata sheet (Fig. 3) except for a surprising lift over the 100-150MHz section. No reason could be found for this withinthe simple signal coupling, and it was assumed to be apeculiarity of the particular sample. The voltage gain figures

Table 1 : Spot gain measurements on theprototype SH221 wideband amplifier.

45MHz50MHz100MHz150MHz200MHz250MHz

15-1dB15-8dB19dB20dB15.5dB14.8dB

500MHz600MHz700MHz800MHz900MHz

15.5dB15.5dB15.5dB15.5dB16.2dB

shown in Table 1 were measured with the input and outputterminated at 75g.

ConstructionConstruction of the complete unit is simplicity itself, and

provided the absolute minimum lead length is used for theinput and output feeders the amplifier will work straight off!An RS/Doram diecast box was used, with signalconnection via the shortened central pins of standardcoaxial sockets.

The Eagle MT150 mains transformer has two 0-12Vsecondary windings which are connected in series to give aneffective 0-24V output. Having completed construction andtesting of the prototype, I reflected that despite the advancesin modern technology, enabling amplifier capsules to beproduced in miniature form, the power supply still looksenormous when the two are seen side by side!

In passing, note that the two transistors in the unit runvery slightly warm to the touch. This is normal for thecircuit and no special precautions are necessary.

12V VersionSGS/ATES have also released preliminary details of a

second, similar hybrid amplifier, type SH120A. Its physicaland electrical characteristics are similar to those of theSH221 except that it requires 12V at 20mA.

AvailabilitySGS/ATES inform us that the SH221 is stocked by

Hawnt Electronics Ltd., Firswood Road, BirminghamB33 OTQ (telephone 021-784 2485), and that the smallquanitity (0-24) price is £8.35 plus VAT at 121%. Theauthor wishes to express his thanks to SGS/ATES for theirprompt help and attention.

TELEVISION JULY 1978 461

Test Report:B & K Model 530 Semiconductor

Tester

B & K PRECISION, the American makers of test equipment,are not as yet well known in the UK. They produce a vastrange of test gear intended mainly for use in radio and TVservice work and for the radio amateur. The equipment inthe range is reasonably priced in view of its capabilities andwe are reporting here on one example, a comprehensivesemiconductor tester.

The 530 has facilities for checking all the importantparameters of all types of semiconductor devices likely to beencountered in the entertainment, light industrial andamateur spheres, with the exception of diacs and triacs. Afull list of its capabilities appears in the accompanying table,from which it will be seen that it can do anything short oftracing characteristic curves!

In -circuit tests can be made with in most cases nonecessity for disconnection of the device. At thecommencement of the in -circuit test it's not necessary toknow the polarity, lead -out identity or whether the device isbipolar or f.e.t.

A six -position switch in conjunction with a leadidentification window and two LEDs indicate the polarity,type and pinning of the device as well as confirming that itfunctions. A loudspeaker is fitted, and will perk up when adevice tests good for "eyes -off" testing. The test signal forthe "good/bad" check is a pulsed waveform, with low duty -cycle for best results when testing in the presence ofshunting circuitry.

Out -of -circuit TestsThe other tests are made with the unkown device out of

circuit, and with the lead -outs having been identified by the

The B & K 530 semiconductor tester.

E. Trundle

first go/no go test. Beta or Hfe is indicated by a clear meterdirectly calibrated, and can be measured under high and lowdrive conditions. In the former case, no less than 2A can bepassed through the device, but the same pulse technique asin the first test is used with a 1% duty -cycle to avoid overdissipation in power transistors and obviate the risk ofdamage to signal types. For f.e.t.s the same meter providesa directly calibrated readout of the equivalent parametergm.

The leakage current test is carried out by applying anadjustable d.c. potential between the electrodes in question,any resulting leakage current being indicated on the meter.Leakage in any mode may be checked, and because of thewide variations possible the meter is driven by an Ingeniousfour -stage circuit each section of which drives a segment ofthe meter. This results in an approximately logarithmiccurrent scale capable of resolving with ease any currentfrom a microamp to five milliamps. For applied voltages upto 10V, leakage current is limited to 5mA by the internalcircuitry. For test voltages above 10V the current is limitedto 100,uA.

This brings us to the breakdown voltage test. Allsemiconductor junctions will break down at some point ofreverse -bias voltage, the most common example being thezener diode in which the reverse breakdown voltage is theprimary parameter. Except for MOSFET devices, thisbreakdown is not destructive provided the current is limitedto a suitably low value. These requirements are met in the530, and a calibrated potentiometer is provided with whichthe applied voltage can be wound up to 100V. A suddenincrease in the leakage current reading signifies the onset ofbreakdown, and the voltage at which this occurs can bedetermined.

HF Testing

Theft testing facility is unusual in any transistor tester. Itgives a fair idea of the high -frequency limitations of thedevice under test. This check is available only for bipolartransistors, which for the purpose of this test are drivenfrom an internal oscillator running at 1, 10 or 30MHzdepending on the setting of theft switch. The selected inputfrequency is amplitude -regulated to a fixed level, while thetransistor under test is automatically biased to a collectorcurrent of 10mA at which most signal transistors providethe highest ft. The transistor in question will provide anoutput proportional to its gain at the selected frequency.

This is processed in a buffer and amplifier, then peak -rectified and applied to a separate meter calibrated in MHzfrom which the ft can be read direct, in three rangescovering ft from 5 to 1,500MHz.

In -circuit Test ResultsWe commenced with in -circuit tests, bearing in mind the

462 TELEVISION JULY 1978

performances of in -circuit testers previously reviewed in thismagazine - the Avo TT169 and the Datest 1. As is usualwith this type of test, i.f., small -signal stages and class Aamplifiers were easily amenable to in -circuit testing. Wemoved on to class B field and audio output circuits to findthat as with the instruments previously tested some direct -coupled devices would check in -circuit while others wouldnot give a reliable indication, depending on theconfiguration of parallel junctions. In the ITT CVC20 TVchassis for instance, the tester checked one half of the fieldoutput stage (T9) satisfactorily but we had to isolate thebase of the complementary device T10 before it gave a"good" indication.

We gained the impression that the in -circuit tests weremore tolerant of shunt resistance and inductance than shuntcapacitance, probably due to the nature of the low duty -cycle of the pulsed test waveform. As an example, themachine happily tested good, in -circuit, the BU126 switch -mode output transistor in the CVC20 chassis. The shuntpath between the base and emitter of this transistor consistsof a 5.64 resistor in series with some inductance! This isremarkably good. Where the shunt path is shorter - lineoutput transistors for instance - the test is misleading unlessthe base of the device is isolated. This was confirmed by theinstrument's ability to test the chopper transistor in a Thorn3000 TV chassis in -circuit but not the line output transistor.