HP-412A-Manual-snprefix-134 电路图.pdf

《HP-412A-Manual-snprefix-134 电路图.pdf》由会员分享，可在线阅读，更多相关《HP-412A-Manual-snprefix-134 电路图.pdf（32页珍藏版）》请在收音机爱好者资料库上搜索。

1、 HP Archive This vintage Hewlett Packard document was preserved and distributed by www. Please visit us on the web ! On-line curator: Dale H. Cook RadioFans.CN 收音机爱 好者资料库 001292 OPERATINGANDSERVICEMANUAL MODEL412A/AR SERIALSPREFIXED:13.4- DCVACUUMTUBE VOLTMETER CepyritlhlHEWLElf.CKAIDCOMANY1961 1$01

2、AOtMILLlOAD,ALOAHO,CAlifOINIA,U.S.A. Printed:JAN1962 RadioFans.CN 收音机爱 好者资料库 Section I TableI-I Model412A TableI-I.Specifications FortotalinsertionresistanceaddO.07ohms copperleadresistanceat250C Accuracy: ,1%of fullscaleon anyrange 10ma 10ma 10ma 1ma 100ua 10ua lua .1ua .01ua ShortCircuit Current 0

3、=0U 1 voltatfull scale;maximumcurrent,1mao(Fullscale correspondsto1. 0 onupperscale.) GENERAL IsotationResistance: Atleast100megohmsshuntedby0.1ufbe- tweencommonterminalandcase(power line) ground CommonModeRejection: Maybeoperatedup to 500 vdcor130vacfrom ground Power:115/230v1%,50-60cps,35 W Dimens

4、ions: CabinetMount:11-1/2in.high,7-1/2in.Wide, 10 in. deep Oulput Impedance: Lessthan2ohmsatde Noise: Lessthan0.1%of fullscaleon anyrange Drift:negligible RackMount: VoltagesandCurrents: enCircuit Volts Weight: FullScale Voltage Drop 1mv 0.9486mv 1mv 0.9486mv 1mv 0.9486mv 1mv 0.9486mv 1mv 3mv 10mv 3

5、0mv 100mv 1000ohms 316ohms 100ohms 31. 6ohms 10ohms 31. 6ohms 1ohm .316ohm .1ohm .1ohm .1ohm .1ohm .1ohm InternalShunt Resistance- .001ma .003rna .01ma .03ma .1ma .3ma 1rna 3 rna 10rna 30 rna lOarna 300ma 1000rna Range InputResistance: Accuracy: ,2% of fullscaleon anyrange OHMMETER HesistanceRange:

6、Resistancefrom1 ohmcenter-scaleto100- megohmscenter-scaleinninedecaderanges InputResistance: 10megohms,1%onImv,3mv, and 10mvranges 30megohms,1% on30mvrange 100megohms,1% on100mvrange 200 megohms:1%on300mvrangeandabove ACRejection: Avoltageatpower line or twice power linefre- quency 40 dbgreaterthanf

7、ullscaleaffects readinglessthan1%.Peakvoltagemustnot exceed1500volts. Accuracy: ,5%ofreadingfrom0.2ohmto500megohms 10%ofreadingfrom0.1to0.2ohm andfrom 500megohmsto5000megohms. AMMETER CurrentRange: Positiveandnegativecurrentsfrom1micro- amperefullscaleto1amperefullscalein thirteenranges VOLTMETER Vo

8、ltage Range: PositiveandnegativevoltagesfromImillivolt fullscaleto1000voltsfullscalein13ranges 1-0 00129-2 RadioFans.CN 收音机爱 好者资料库 Model412A SECTIONI GENERALDESCRIPTION Section I Paragraphs1-1to1-10 I-I.GENERAL. 1-2.TheModeI412A/ARDCVacuumTubeVoltmeter isaprecision,widerange,multipurposeinstrument w

9、hichcoverstheentirerangeofdevoltage,current, andresistancemeasurementsnormallyencountered inelectronicequipment. 1-3.Itmeasuresdevoltagesoverthewiderangeof 0.02millivoltsto1000voltsonthirteenrangesar- rangedin a 1, 3,10sequencefrom1mvfullscaleto 1000 vlullscale.Overallaccuracyonallthirteen rangesisw

10、ithin1%of fullscale.Voltagedifferences canbemeasuredeasilysincetheinputcircuitisiso- latedfromthecaseandfromthepowerlineground. 1-4.DAMAGEINSHIPMENT. 1-5.Inspectandoperatethisinstrumentuponre- ceipt.Section IVincludesaperformancecheckwhich isa goodtestaspartofincomingqualitycontr.olin- spection.Thec

11、heckcanbemadewiththeinstrument initscabinet.Ifthereisanydamage,seetheClaim CorDamage inShipmentparagraphatthebackoCthis manual. 1-6.POWERCABLE. 1-7.Thethree-conductorpowercablesuppliedwith thisinstrumentterminatesinapolarizedthree-prong maleconnectorrecommendedbytheNationalElec- tricalManufacturersA

12、ssociation.Thethirdcontact isanoffsetroundpinaddedtoastandardtwo-blade connector.Thiscontactgroundstheinstrumentwhen usedwith anappropriatereceptacle.Anadaptershould beusedtoconnectthe NEMAplugtoastandardtwo- contact output.When theadapterisused,theground connectionbecomesashortleadfromtheadapter. T

13、hisleadshould beconnectedtoasuitablegroundlor theprotectionoCOfleratingpersonnel. 1-8.115-230VOLTOPERATION. 1-9.A switchlocatedon theinstrumentrearconverts the Model412A1ARforusefromeitheraliS-voltor 230-volt, 50-60cpspowersource.Theswitchchanges the connection ollhedualliS-voltprimarywindings of th

14、e powertransformerCram aparallelcombination toaseriescombination,orviceversa.Switchposi- tionsaremarked115and230. 1-10.Toconverttheinstrumentfrom115-voltopera- tion to230-voltoperation,orviceversa,inserta screwdriverbladeinto theswitchslotandslidethe slotuntilthemarkingindicatesthe line voltage.At 0

15、0129-2 thetimeofthechange,replacethelinefuse.Aone- hallampereslow-blowfuseshouldbeusedfor115- voltqeration;a0.4ampereslow-blowfuseshouldbe usedfor230-voltqeration. CAUTION Besurethe115/230 VswitchIssetatthe properpositionbeforeapplyingpowertothe instrument.Incorrectsettingof theswitch canresultindam

16、agetotheinstrument. Figure1-1.Model412A1AR I-I SectJonll Table2-1 Table2-1.ResistanceRange vsen-CirCUitVolts/Short-CirCUitCurrent Model 412A Range enCircuitVoltsShortCircuitCurrent (1.0 onuppervoltagescale)(0onuppervoltagescale) Xl10mv10ma XI0100mv10 rna XI001 v10ma XI0001 v1ma XI0K1 v100ua XI00K1 v

17、10ua XIMIvlua Xl0M1 v0.1ua XI00M1 v0.01ua 2-000129-2 Model412A SECTIONII OPERATINGINSTRUCTIONS SectionII Paragraphs2-1to2-12 2-1.LOW-LEVELELECTRICALPHENOMENA. 2-2.straylow-levelelectricalphenomenaarepre- sentinone formoranother, innearlyallelectrical circuits.The412Adoesnotdistinguishbetweenstray an

18、dsignalvoltages;itmeasuresnetvoltage.Thus, whenusingthelowervoltageranges,considerthe possibilityoflow-levelelectricalphenomena.Ther- mocouples(thermoelectriceffect),flexingofcoaxial cables(trlboelectriceffect),apparentresidualcharges oncapacitors(dielectricabsorption),batteryaction of twoterminalsm

19、ounted onanimperfectinsulator (galvanic action)allcanproducevoltageswithinthe rangeofthe412A. 2-3.The412Avoltageprobe,current/resistance leadandcommonleadaredesignedtohaveavery lowthermoelectriceffectwithcopper,themostcom- pleteelectricalconductor.However, you mayen- counterothermaterials.Forexample

20、,theleadsof manytransistorsaremade of a mixtureofiron, nickel andcobalt knowncommerciallyasKovar.Fernico, etc.ThismaterialmakesSverygoodthermocouple withcopper:about40uv/Cwithrespecttoaref- erencejunction. 2-4.Wheneverpossible,connectthe412Aleadsto copperandmalntatothepointsofconnectionatthe same te

21、mperature,preferablyambient temperature. With theleadssoconnected,anyvoltageindicatedby the412Aisdevelopedwithinthecircuitundertest. 2-5.OPERATINGINSTRUCTIONS. CAUTION Donotoverloadtheinstrument.Amplifier input,currentshunts,andinternalresistance standardsarenot protectedfromextreme overload.Momenta

22、ryoverloadstentimes fullscalewillnotdamagetheinstrument. 2-6.TurntheModel412Aonandallowa fewminutes warmup. 2-7.VOLTAGE MEASUREMENT. a.SetFUNCTIONselectortoVOLTS. b.SetPOLARITYswitchtodesiredpolarity. c.SetRANGEswitchtodesiredrange. d.UseVOLTSandCOMleadstoconnectinstrument acrosscircuit or component

23、. and read voltage. 2-8.CURRENT MEASUREMENT. a.Set FUNCTIONselectortoMA. b.SetRANGEswitchtodesiredrange. 00129-2 c.De-energizecircuittobetested. d.UseMA/OHMSandCOMleadstoconnectinstru- mentintocircuit. e.Energizecircuit,setPOLARITYswitchfor upscalereacting, and read current. Note When measuring curr

24、ent, besurethereis no connection between the chassis-ground. andcabinet-groundterminalsoftheDCAMP- LIFIEROUTPUTconnector. 2-9.RESISTANCE MEASUREMENT. a.SetFUNCTIONselectortoOHMS. b.De-energizecircuitto be measured. c.UseMA/OHMSandCOMleadstoconnectin- strumentacrosscircuitorcomponent. d.Selectrangewh

25、ichbrlngsmeterpointerasclose aspossibletomidscale,and readresistance. 2-10.Whenmeasuringtheresistanceofnon-linear devicessuchascrystaldiodesortransistors,you maywanttoknowthevoltageappliedtothedevice and!orthecurrentthroughitatthetimeofmeasure- ment.Byusingtable2-1andtheuppervoltagescale onthemeterf

26、ace,youcandetermineboth.Themeter readingisdirectlyproportionaltothevoltageacross thedevicebeingmeasured,andthemeterreading subtractedfromfullscaleisdirectlyproportionalto thecurrent.Forexample,ontheXlOrangetheupper voltagescaleisaO-IOOmvscaleanda10-0mascale. I!themeterIndicates.25ontheresistancescal

27、e, thedevicebeingmeasuredhasanequivalentresistance of 2. 5ohms.ButthemeteralsoIndicates.2 onthe uppervoltagescale;thus,fromtable2-1,thedevice has2.5-ohmsequivalentresistancewith20mvacross itand8maflowingthroughit. 2-11.OPERATION WITH A RECORDER. 2-12.Toobtainpermanentrecordsof412Areadings, connectar

28、ecordertotheDCAMPLIFIEROUTPUT connectorandoperatethe412Aasdirectedabove. Theoutput of the 412AisIvoltatlullscale;ifneces- sary,externallyattenuatethe412Aoutputtomatch itwithrecordersensitivity.Maximumratedload currentfromthe412Ais1 rna.Aloadresistanceof lessthan1000ohmsmaycausetheloadcurrentto excee

29、d1rnaandthus causeerrorsinmeter indica- tion andamplifier gain. , 2-1;2-2 Model412A Sectlonm Paragraphs3-1 to3-4 SECTIONIII CIRCUITOPERATION 3-1.GENERAL 3-2.The Model 412Aisbasicallya O.toO.9milli- volt devoltmeter.Precisionvoltagedividers,shunts, andreferenceresistorsextendtherangeofthebasic voltme

30、terandpermitcurrentandresistancemeasure- mentsaswell. 3-3.CIRCUITOPERATION. 3-4.WiththeFUNCTIONselectorandRANGEswitch properlyset,voltageisappliedtoa photoconductlve modulatorthroughalow-passfuter.Seefigure3-1. Thefilterattenuatesaccomponentspresenton any input signal,andthemodulatorconvertstheremai

31、ning dccomponenttoasquarewave.Asynchronous- motor-driven,light-beamchoppersetsmodulator frequencyat5/6power-linefrequency.Anac-coupled amplifieramplifiesmodulator outputabout500,000 times.Ademodulatorsynchronized witbthemodu- latorbythelight-beamchopper,convertsamplifier outputtodc.Theoutput ofthede

32、modulatorisfiltered and applied through a cathode followerto1)afeed- backnetwork,2)theDCAMPLIFIER OUTPUTtermi- nalsand3)anoutputindicator.The feedback network stabilizesthedcgain ofthemodulator-amplifler- demodulatorsystemtoa valueof1111,therebypro- vidinganoutput of 1voltforaninputof0.9millivolt. T

33、heoutputindicatorisa0-1voltmeter.ThePO- LARITYswitchpermitsreversalofindicatorcon- nectlons,Ifrequired,toobtainup-scalereadings. ThePOLARITYswitchisdisabledwhentheFUNCTION selectorissettoOHMS. v -.-_._._-._- 0 .,. r-O: Llcn- r-lUI-1 IIYlUI C_, OM51, , , 0 , , 0, , , , , , , , , , 0 , v , , , .,. .y.

34、 ,0: At, . II ., Aift.lff AtSflK.I. u_ mlu II I. -1. flLTlI 1 - fOllOnl (5: 0 0 0 0 , 0 0 Y 0 , 0 ifthemeterrequiresadjust- ment,seeparagraph4-15. 4-10. VOLTMETER CHECK. a.TurnVoltmeterCalibrationGeneratoronand allow5minutewarmup. b. Connect4l2Atovariablepowersource,setline voltagetoratedvalue (115/

35、230v)andturnModel 4l2A on.Allow Model 4l2A a lewminutestowarmup. c.SetFUNCTIONselectortoVOLTSandPOLARITY switch to+. d. Connect VOLTS andCOMleadstoOUTPUTcon- nector01VoltmeterCalibrationGenerator. e.Check 412AreadingversusVoltmeterCalibra- tionGeneratoroutput oneach4l2Arange.Maximum 4l2Aerrorshouldb

36、enogreaterthan1%01lullscale. Note When checkingMode14l2Aonits.003 and .001 voltranges,settheselectorswitchofVolt- meterCalibrationGeneratortoOFFand note any 412Azeroolfsetduetothermoelectric voltage. Addorsubtract,asappropriate,any olfsetlromthe4l2Areadingwhen Voltmeter Calibration Generatorselector

37、switchisset toDC+. I. Check 412Ametertrackingon+and -1 volt ranges.Maximumerrorshouldbenogreaterthan 0.01volt. g.Repeat step e (on onerangeonly)atlinevolt- age01103and127volts. 4-11. Mn.LlAMMETER CHECK. a.Set line voltage to 115volts. b.Set FUNCTIONselectortoMAand POLARITY switchto+. c.Connect 412A

38、toVoltmeterCalibrationGenera- atorasshown in figure4-2. d. Check4l2Aasshown Intable4-1. Note SwitChing throughthecurrentrangesfrom10 to 1000doesnot changethecurrentshunt. Only the voltageattenuator,checked Inpara- graph4-10 above, changes.(Seeligures4-6, 4-7, and4-8forsimplifiedswitchingdetails.) 41

39、 Section IV Paragraphs4-12to4-17 Model 412A Figure4-2.EquipmentSetuplorCurrentCheck 4-13.CABINETREMOVAL. a. Unplugpowercordfrompowersource. wheninstnunentis1)atnormalqeratingtemperature, 2)inItsnormalqeratingposition, and3)turnedoff. Zero-setaslollowstoobtainbestaccuracyandme- chanicalstablllty: a.A

40、llowtheinstrumenttooperateforatleast20 minutes; this allowsmetermovement to reach normal operatingtemperature. b.TurnInstrumentoff and allow30secondsforall capacitorstodischarge. c.Rotatemechanicalzero-adjustmentscrewclock- wiseuntilmeterpointerIstoleftofzeroand moving upscaletowardzero. d.Continuet

41、orotateadjustmentscrewclockwise; whenpointerisrightonzero.Ifpointerover- shootszero,repeatstepsc and d. e.WhenpointerisexacUy onzero,rotateadjust- mentscrewapproximately15degreescounterclock- wise.ThisisenoughtoIreeadjustmentscrewfrom themetersuspension.Ifpointermovesduringthis stepyoumustrepeatstep

42、sc throughe. Note TheHumBal.controldoesnotaffectthe120- cpsripple.Adjust onlyforminimum10-cps (or8-1/3cps)ripple.WiththeVOLTSlead connectedtoCOM., andthePOLARITYse- lectorto+,the412Ameterwill show amini- mumreadingwhenthehumbalanceadjust- mentiscorrectlymade. 4-17.HUMBALANCE ADJUSTMENT. a.Turninstru

43、menton and allow a lewminutes warmup. b.SetFUNCTlONselectortoVOLTS. c.ConnectoscilloscqetoDC AMPLIFIER OUT- PUTconnector. d.Adjust HumBal.(R126),lorminimum10-cps signalonoscilloscqe.(Ifpower-lineIrequency Is 50cps,adjustlorminimum8-1/3cpssignal.)See figure4-11forlocationof R126. BD-S-5B WLTSCOMs SER

44、IES RESISTOR SEETABL NODEL738A VOLNEYERCALIBRATOR Note AvoidtouchingtheRANGEswitchwafers.Adlrty switchcandegradeinstrumentperlormance. b. Remove tworetainingscrewsfrominstrument rear. c.SlideInstrumentchassisforwardout ofcabinet. Bezelringremainsattachedtofrontpanel. 4-14.ADJUSTMENTS. 4-15.MECHANICA

45、LADJUSTMENTOFMETER ZERO. 4-16.Whenmeterisprqerlyzero-set,pointerrests over thezerocal.1bration mark on the meterscale 4-12.OHMMETER CHECK. a.Set FUNCTIONselectortoOHMS. b.Connect1%resistor011,10, 100, 1000,10K,100K, 1M,10Mand100MohmsbetweenMA,!OHMSandCOM leads.Withapprqrlaterangeselected,metershould

46、 indicate betweenO.95and1.05ineachcase. Table4-1.AmmeterCheck OutputofVoltmeterSeriesModel 412AModel 412A Reading Calibration GeneratorResistanceRange(2%of/ullscale) 1 volt1.00M0.1%.0011.0 3 volts1.00M 0.1%.0033.0 10voltsLOOM0.1%.011.0 30voltsLOOM0.1%.033.0 100 voltsLOOM0.1%11.0 300voltsLOOM0.1%.33.

47、0 300 volts300K0.1%1.01.0 300voltslOOK0.1%3.03.0 300 volts30K 0.1%(5watts)10.01.0 300 volts30K0.1%(5watts)30.01.0(on0-3scale) 4-200129-2 Model412A 4-18.CATHODE FOLLOWER BIAS ADJUSTMENT. a.Set RANGEswitchfullclockwise- onestepbe- yond 1000. SectionIV Paragraphs4-18to4-24 4-20.OHMMETER ADJUSTMENT. a.S

48、etFUNCTIONselectortoOHMSandRANGE switchtoXIK.BesureMA/OHMSandCOMleads arenot connected throughsomeexternalresistance. b.Adjust BIAS ADJ. (R116),tosetmeterpointer approximatelyonzero.Rl16isiocatedoninstru- mentrear.Thisadjustmentisnotcritical,sinceany deviationfromzeroisreducedmorethan100times whenth

49、eRANGEswitchison anyoperatingposition. 4-19.AMPLIFIERGAIN CALffiRATIONANDMETER CALIBRATION. a.Connectequipmentasshowninfigure4-3.You mayreplacethetestvoltmeterwithanyhighresis- tance meter device which canresolve10mY. b.SetVoltmeterCalibrationGeneratoroutputto +1volt. c.On412Aundertest,setFUNCTIONselectorto VOLTS, POLARITYswitchto+, RANGEswitchto1. d.Adjust GainCal(R119),forzeroontestvolt- meter.Forlocationof R119seefigure4-11.A10- mv readingontestvoltmeter indicates1%errorin gain