HP-Service-Note-202B-1 电路图.pdf

HP Archive This vintage Hewlett Packard document was preserved and distributed by www. Please visit us on the web ! On-line curator: Glenn Robb This document is for FREE distribution only! RadioFans.CN 收音机爱 好者资料库 202B-1 PROCEDUREFORREPLACINGMECHANICALDRIVECABLES ONMODEL202B Thephotographsanddrawingsincludedhere,arefortheidentification ofpartstnentionedinthesenotesandtoaidincarryingouttheinsg:.uctions.If difficultiesareencountered,pleasewritetothefactoryServiceDeparttnent, describingyourtroublesandgivingtheserialandtypenutnbersofyourinstrutnent. GENERAL: Acotnpletesetofreplacetnentdrivecablesforthe202ILconsistsof: 115tnaindriveloopedononeend. 1IItnaindriveloopedononeend. 210capacitordriveloopedononeend. 2setsof4and4-1/2cablesconnectedwith1/2 11 coilspringwithall endslooped. 4clatnpingeyelets. ThebaSICprincipleofoperationofthedriveassetnblycanbeseenby carefullystudyingtheillustrationinfig.2.Briefly,thetwocables(27)and(35) areconnectedtothelateraldriveshaftpulley(30)andheldintensionbythehelical spring(24).Radialtnotlonistranstnittedtocapacitorbanks,(1)and(17),through thecapacitordrivepulleys(5,10, 18,and20). ,Therighthandbank(1)isdriventhroughpulley(5)whichclatnpstothe turneddownshoulderonpulley(30)bytneansofasetscrew(6). Motionisthencetransferredtothelowerpulley(10)bytneansofthe cables(7)and(12). Thelefthandbankofcapacitorsisrotatedinasitnilartnannerbyashaft (42)whichisclatnpedInthecenterofthedrivepulley(30),andagaininthecenter oftheupperdrivepulley(18). Whenproperlyaligned,allfourcapacitorbankstnovesitnultaneouslyas thepanelfrequencycontrolisrotated. REMOUNTINGOFDISLODGEDCABLES: Ittnaybenecessarytoretnountthecablesduetothedislodgingofthe cablesfrotnthepulleytroughs.Thisconditionisusuallytheresultofshipping 7/28/54 HEWLETT-PACKARDCOMPANY395PageMillRoad-Pa/:lifriafA: J .- RadioFans.CN 收音机爱 好者资料库 Page2of9 damageorbythefrequencycontrolbemgrotatedviolentlyagainstthestops orbythecontrolsbelngforcedagainstthetunershippingblocks.Thesewooden blocksareinstalledtopreventtheswingingofthecapacitorbanksduringship- pingandmustberemovedbeforeattempbngtoturnthefrequencycontrol. Ifthecablesdonotshowabrasionorwornspots,theymayberemounted, necessitatingonlyashghtadjustmentofthefrequencycalibration.Howeverif thecablesneedreplacement,completerecalibrationmaybenecessary. ToolsrequiredforthisOperation: Apairoflongnoseplierswithelectricaltapewrappedaroundeachjawto preventdamagetothecable,ascrewdriversimilarlypadded,aPhillipsscrew- drieranda#8anda#10allenwrench. PROCEDURE: 1.Removetopcoverbyremoving4screwsattherearoftheinstrument. 2.Examinecablestoseewhichoneisdislodgedordamaged.Ifthecable inquestionisaccessiblewithoutfurtherdisassembly,remountcablein thefollowingmanner. REMOUNTINGOFDISLODGEDMAINDRIVECABLES: Thecables(27)and(35),(fig.2)counterbalanceeachotherandarekept atpropertensionbythecoilspnng24). Makeascribemarkonhub(23)andshaft(43)toindicatetheirrelative position. InremovingeitherofthesecabLes,itisnecessarytorelaxthetension bylooseningthesetscrew(22)toenablethehub(23)torotateclockwise,thus slackeningthecables.Thecablesmaynowberemountedontheirrespective drumsandpulleys,asshowninfig.2. Torestoretension,rotatehub(23)counter-clockwiseuntilthetwoscribe markslineupandtightensetscrew(22). CAUTIONDonotdisturbthesetscrew(32)asthisholdsthepositionofthemain drivecablerelativetothefrequencydial. 3.Ifthecableorcablestobereplacedorremounted,arenotaccessible, removethemechanicaldriveassembly(togetherwiththefrontpanel) fromtheinstrument. REMOVALOFDRIVEASSEMBLY: 1.RemovefourPhillips-headmountingscrewsfromthecornersofthe frontpanel. 202B-1 7/28/54 RadioFans.CN 收音机爱 好者资料库 I Page3of9 2.Disconnecttheeightwiresconnectmgtheassemblytotheinstrument. 3.Removefrontpanelandmechamcaldnveunit. 4.Placetheassemblyrightsideup onthebenchwiththefrontpanel awayfromyou.Placethefrontpanelinabenchviseorblockup theassemblyinalevelpositIon.Youarenowreadyforthere- placementorremountingofthecables. Clockwiseorcounter-clockwise,rightorleftwhenreferredto,in thissheet,arewiththeunitintheaboveposition. REMOVINGMAINDRIVECABLES: Inremovingeither(27)or(35)itisnecessarytoreleasethetensionby looseningsetscrew(22)asexplainedinprecedingsection.Removethescrews holdingthecableendsandthecablescanbetakenfromtheinstrument.Before removingcables,examineeachonecarefullytodetermlnethemannerinwhich itwasmounted.Anysharpedgesorprojectionsthatmightwearthecables, shouldberemovedwithafileorsandpaper. REPLACINGMAINDRIVECABLES: Withcapacitordrivesettothehighfrequencystop,attachun-loopedend ofthe11cableundertheheadofscrew(36)onpulley(30).Windthecable1/4 turn,towardthefrontpanel,onthelargediametergrooveandthenwindclock- wiseondrum(33).Inserta4-40 x1/8roundheadmachinescrew34)through theloopinthecableandattachtodrum. Withcapacitordrivestillatthehighfrequencyend,attachun-loopedend of15wirecableundertheheadofscrew(29)onpulley(30).Windcable2/3 turnonthesmalldiametergrooveintheoppositedirectionfromtheothercable andthenwindcounterclockwise1-1/2turnsaroundtheidler(28).Bringthe cablecounter-clockwisearounddrum(25).Securetheloopinthecabletothe drumwitha4-40 x1/8roundheadedscrew26). Holdthedrivefirmlyagainstthehighfrequencystop.Insert#8allen wrenchintosetscrew(22)androtatehub(23)1/2turninacounter-clockwise directionandtightensetscrew.Rotatedrlvefromendtoendaboutahundred timestomakesurecableswindproperlyondrumsandtotakethestretchoutof thecables. Thelengthofcablesgivenhere,arebeforetheendshavebeenlooped. Incasethereplacementcablesarethenewplasticimpregnatedtype, theywillrequireadifferenttechniqueasexplainedinsectionentitledINSAL- LATIONOFCLAMPINGEYELETSONCABLEENDS. 202B-1 7/28/54 Page4of9 REMOUNTINGOFDISLODGEDCAPACITORDRIVECABLES: Theprocedureisthesamefortherightandleftcapacitordrives.The descriptionheredealswiththerightside. Thecables(7)and(12)arecounter-balancedbythetensionofthesmall coilsp:;.-ingoncable(7). Shouldthe(12)cablebecomedislodged,procedeinthefollowingmanner: Withthefrequencycontrolturnedtoaboutmidwayonthefrequencydial,holdthe upperpulley(5)rigid.Rotatethelowerpulley(10)soastostretchthecoilspring slightly.Theresultantslackincable(12)shouldpermitremounting.Whenthe cableisinitsplace,releasethelowerpulleytore-establishthepropertension. WARNING:Donotdisturbsetscrew(6)whichanchorspulley(5)todrivepulley (30)asrelationshipofcapacitordrivepulleystomaindrivepulley, willbedisturbed. Referencetofig.2willmaketheremountingofcable(7)asimpleprocedure. Rotatethetuningcontrolseveraltimes,toensurepropeoperationof remountedcables. Althoughitisunlikelythatthecalibrationoftheinstrumenthasbeendis- turbeditisadvisabletorechecktheunitasexplainedintheREALIGNMENT section. REPLACEMENTOFCAPACITORDRIVECABLES: Removecables(7)and(12)onrighthandside,inthefollowingmanner: 1.Removepanelanddriveasselublyasdescribedinthesectiononre- mountingofcables. 2.Unsolderoneendofheavybuswire,connectingtherighthandcapacitor bankwiththelefthandbank. 3.Scribematchmarksacrosspulleys(30)and(5). 4.Loosenallensetscrew(6)whichclampspulley(5)totheshoulderof pulley(30). 5.Removetwomountingscrewsandwashersholdingtheleftendofthe righthandcapacitorbanktothecasting.Removenutandwasherholding therightendofthisbanktothecasting. 6.Carefullyremovecapacitorbankfromtheinstrumentandstanditon itsrightendwiththepulleysup. 202B-1 7/28/54 Page5of9 7.Takeoutscrews(11)and(13)andremovethe10cable(12)fromthe instrument. 8.Sliptheun100pedendofthereplacementcablethroughtheholein pulley(5).Pullitthroughandrunitthroughtheholeinpulley(10). 9.Makealoopintheunloopedend,usingthemountingscrewasa formandsolderthecable,orinthecaseoftheplasticimpregnated typecable,installtheclampingeyelet. 10.Windthecableasshowninfig.2andfastentheendswiththeir mountingscrews(4-40 x1/8roundheadmachinescrew.) Thecoilspringoncable(7)consistsoftwolengthsofcablejoinedbya smallcoilspring. 1.Removethecablebyremovingthetwomountingscrews(8)and (9) 2.Installthereplacementcablewiththelonger,4-1/2sectiondown andthe4sectionatthetop.Bothendsofthiscablearelooped readyforinstallation. 3.Windthecableasshowninfig.2andfastentheendswiththe mountingscrews(8)and(9). 4.Placethecapacitorbankbackinitsproperpositionagainstthe casting,withpulley(5)overtheshoulderofpulley(30).Replace andtightenmountingscrewsandnut,lineupscribemarkson thetwopulleysandtightensetscrew(6). Toremovethecapacitordrivecable(7)or(12)onthelefthandcapacitor bank,itisnecessarymerelytoremovethemountingscrews(8)and(9)or(11) and(13)andremovethecablefromtheinstrument.Inthiscase,itisnotneces- sarytodismountthebankfromthecasting.Ininstallingthesecables,thesame techniquemaybeused,asoutlinedintheinstructionsfortherighthandside. OLDMODELS: Incertainoldermodels,thetunerconsistsofthreesetsoffour-gang capacitorsinsteadofthecurrentfoursets.Inthismodel(typeno.102747and earlier)thetechniqueofreplacingdrivecablesisthesame,exceptthattheright handcapacitordrivecableisnotincluded,therefore,theremovaloftheright handcapacitorbankfromthecastingisnotnecessary. 202B-1 7/28/54 Page6of9 INSTALLATIONOFCLAMPINGEYELETSOITCABLEEIDS. CLAMPING ,SLEEVE CABLE PULLEY-. CABLE LOOPEDTHRU SLEEVE CRIMPINGCABLE SECURE CABLEWITH SCREW Fig.1. Newtypecabesareconstructed ofplasticcoatedcopperwovenwirewith astainlesssteelcore,andcannotbesat- isfactorilysoldered. Thesecables,togetherwiththeneces- saryclampingeyelets,maybeobtained fromthefactory.Theyaresuppliedwith oneendalreadyequippedvithaclamping eyelet,andtheotherendbaresoastoper- mitittobethreadedthtoughholesprovided inpulleys.(Seefig.2.) Fig.laatleftshowsbareendofcable threadedthroughholeinpu.l1eyandeyelet readyforinstalling. Fig.Ibatleftshowscableendlooped backthrougheyeletreadyforcrimping.Size ofloopandlengthofendplotrudingfromeye- letshouldbetheS:l.meastheotherendof thecable. Fig.Ieshowsmethodofcrimpingcable eyelet.Taplightlywithasmallplastic headedhammeruntileyeletisflat,thenadd acentergrooveasshown,bymeansofa screwdriverandahammer. Fig.Id.Cableisnowproperlyclamped andmaybeattachedtotl1.epulleyusinga smallscrew. WARNING:Iftheca.blesaremadeoftheun- coatedmaterial,th-:=clampingeyeletswillnot hold.Theunloopedendmaybeformedaround themountingscrew,foldedbackuponitselfand soldered. 202B-1 7/28/54 Page7of9 MECHANICALALIGNMENT Iftherelationshipofthevariouscapacitorbanksanddrivepulleyshas beenmaintained,thefrequencycalibrationoftheinstrumentwillbeasimple matter;otherwisetheprocedurewillbecomemorecomplex. Theinstructionsherearefortheunitwiththefoursetsoffourgang capacitors. 1.Besurethatthestoparm,locatedinbackofthedial,strikesthe pinbeforethecapacitorrotorsstriketheframesineithertheclosed oropenpositionofthetuner.Ifthisdoesnotoccur,loosentheset screwwhichholdstheshaftoftheoffendingcapacitor.Rotatethe capacitorsothatitsrelativepositionisthesameastheotherbanks andretightenthesetscrew. 2.Whenthebanksareopenalltheway,thespacebetweentherotorsand thecapacitorframesshouldbeapproximatelythesame.However,if thereisaslightdifference,thisshouldnotbecorrecteduntilthe frequencycalibrationhasbeenchecked.Theunitmayhavebeencali- bratedinthISconditIonoriginally.Anyalterationofthisrelationship maycausepoortrackingofthefrequencydial. 3.Ifthelefthandbankdoesnothavethesamerelativepositionasthe righthandbank,loosenthesetscrew(6),holdingpulley(5)tothe shoulderofpulley(30),turnthelefthandbanktoitsproperposition andretightensetscrew(6). FREQUENCYCALIBRATION: Theunitshouldbeleftonforatleastanhourbeforethecalibrationshould beattempted. Equipmentrequiredforthisoperation: Aninsulated,non-metallicscrewdriver Asmallmetalscrewdriver A#8and#10Allenwrench Asuitablepatchcord Afrequencystandardsuchasan-hp-Model524A,524B,522Aor522B. Anoscilloscopemaybeused,inconjunctionwithan-hp-Model100A, 100B,lOOC,or100D. AnACvoltmeter(400A,400B,400C,400D,or410B) 1.Settherange-switchpanelknobtoX100andthefrequencydialto 51.(bottomofdial.) 2.Witha1000ohmresistiveloadacrosstheoutputterminals,connect theoutputtoanACvoltmeterandtoyourfrequencymeasuringsetup. 202B-1 7/28/54 Page8of9 3.Settheoutputvoltagetoareferencepointonthemeter. 4.TurnthediJto5(topofdial). 5.Byadjustingthetrimmercapacitor(C22)theoutputvoltagemaybe broughttothesamereferencelevelonthemeterandatthesame time,thefrequencyshouldbeb:;:oughtoncalibrationatthispoint onthedial. 6.Ifflatteningtheoutputdoesnotbringitonfrequency,checkthe calibrationatthemiddleofthediaLThecalibrationmaybeoffthe sameamount.Inthiscase,removethemaintuningknob(topone) andloosenthefour#10allenscrewsholdingthedialtothehub. Changethedia1sposition,relativethehub,untilthecalibrationis approximatelyonatthemiddleofthediaL 7.Setthecalibrationonatthetopofthedialwithtrimmer(C22). Indoingso,youmaybeunabletoflattentheoutputfrequencyresponse. Ifthisisthecase,adjustthevalueofthefixedcapacitor(C2)andtry again. CAUTION:Thiscapacitormustbeofhighquality,suchasasilvermica ceramicon.TheslIghtestleakageherewillcauseanerrorin calibration,especiallyontheXlrange. 8.Checkthecalibrationalloverthedialandonallotherranges. Ifthecalibrationisconsistantonallranges,turnbacktotheXIOO range.Anyerrorincalibrationmaynowbecorrectedbybending theplatesinthetuningcapacitors. BENDINGPLATES LOnXIOOrange,checkcalibrationatthetopofthedial.Setonif necessary,with(C22)asbefore. 2.Check13onthediaLIfitisoffcalibrationhere,bendtheplatesto bringiton.Ifthefrequencycomesintoohighonthedial,bendthe outerrotorplatesofeachsection,wheretheyaremeshed,awayfrom thestatorplates.Trytobendeachplatethesameamount.Ifthe frequencycomesintoolowonthedial,theplatesshouldbebentin. Usecautionheretomakesurethattheplatesdonotshortout. 3.Turnto2onthediaLIfnecessary,dothesamehere,makingsure thatyoudonotdisturbtheadjustmentat3onthediaL 4.Checkatl,.7and.5onthedial,Bendtheplatesifnecessary. Donotattempttoolargeanadjustmentwiththismethod.Ifthedial trackingistoofaroff,slipthedialonthehubagainandstartover. 202B-1 7/28/54 Page9of9 RANGE-SWITCHADJUSTMENT: Checkthecalibrationatthebottomofthedialonallranges.Oneor moreoftherangesmaynotlineupwiththeothers.Inthiscase,changethe valueofthe1/2wattpadderresistorsinserieswiththeprecisionrange-switch resistorsforthoseparticularranges.Youwillfindthatincreasingtheresistance willbringinthefrequencieshigheronthedial.Therangeswitchresistorsare inmatchedpairs.Donotmaketoogreatachangeintheresistanceofoneside. Thisunbalancewillchangetherelativeoutputvoltageforthisrange.Thepadders onbothsidescanbechanged,thusmaintainingtheproperbalance. LAMPCAPACITOR: CheckthecalibrationatthetopofthedialontheXlOKrange.The calibrationissetonatthispointbyadjustingthevalueofthelampcapacitor(C7). Thetechniqueofaligningtheoldthree-gang-capacitormodelisessentially thesame,exceptthatinthisversion,twotrimmercapacitorsareprovided, facilitatingthesimultaneousadjustmentofboththefrequencyandtheoutputvoltage atthetopofthedial. 202B-1 7/28/54 -.IN -0 NN OOt;g -. J1 17 Fig.Z. 2 12 9 14 13_._ ExplodedViewofMechanicalDriveUnit . TopView Fig.3. BottomView 202B-l 7/28/54 _SIA1 - RI+R2.85.7M RII.R12oag.2M R3+R4.RI3+RI4.8.5M R5+R6.RI5+Rle.8K RT+RI.Rlr+RIS.85K R9+RIO.RI9+R2Q.8500 IOUTPUTI ) 6 0 Q:- o 0 Q:!l C20-8<F0ILOADI I -97 CI82.21JF 1 II : . :lli:i o-o 0 Q: Q:CD Q: , C1930JLF +75 t OSC.VOLTAG