HP-740B-Manual 电路图.pdf

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1、 HP Archive This vintage Hewlett Packard document was preserved and distributed by www. Please visit us on the web. For free distribution only! Thanks to on-line curator: Marc Scheerders for supplying and scanning this vintage document. RadioFans.CN 收音机爱 好者资料库 ID o . L 1: I 74.08 DCSTANDARD/ DIFFERE

2、NTIAL VOLTMETER ;. . OPERATINGANDSERVICEMANUAL HEWLETTPACKARD 1: 1J . o OJ RadioFans.CN 收音机爱 好者资料库 -HEWLETTPACKARD-. CERTIFICATION TheHewlett-Packard Company certifiesthatthis instrument was thoroughly tested and inspected and found to meet its published specifications whenitwas shipped from the fac

3、tory.TheHewlett- Packard Company further certifies that itscalibration measurements are traceable to theU.S.National Bureau of Standards to theextent allowed by the Bureaus calibration facility. WARRANTYANDASSISTANCE AllHewlett-Packardproductsarewarrantedagainstdefectsin materialsandworkmanship.This

4、warrantyapplies for one year from thedateofdelivery, or, inthecaseofcertain major componentslisted intheoperating manual, forthespecified period.Wewillrepair or replace products which provetobedefective duringthewarranty period.Nootherwarrantyis expressedorimplied.Wearenotliable for consequential da

5、mages. Foranyassistancecontactyour nearestHewlett-PackardSalesand ServiceOffice.Addressesareprovidedattheback of this manual. RadioFans.CN 收音机爱 好者资料库 01794-1 OPERATINGANDSERVICEMANUAL (HPPARTNO.00740-90002) MODEL740B DCSTANDARD/DIFFERENTIAL VOLTMETER SERIALSPREFIXED:610-,722- CopyrightHewlett-Packar

6、dCompany1966 P.O.Box301,Loveland,Colorado80537U.S.A. Printed:AUG1967 Model740BTableofContents TABLE OFCONTENTS SectionPageSectionIV(Contd)Page IGENERALINFORMATION.1-14-115.PowerSupplies.4-10 1-1.Introduction.1-14-127.ChopperNeonDrivers4-11 1-3.Description.1-1 1-5.DCStandard.1-1SectionPage 1-7.Differ

7、entialVoltmeter.1-2VMAINTENANCE.5-1 1-9.HighImpedanceVoltmeter1-25-1.Introduction5-1 1-11.Amplifier1-25-3.RequiredTestEquipment5-1 1-14.InternalAdjustment.1-25-5.PerformanceTests5-1 1-16.Specifications.1-25-12.DCStandardPerformanceTest5-2 1-18.InstrumentIdentification1-25-25.DifferentialVoltmeterand

8、High 1-20.AccessoryEquipmentSupplied.1-21mpedanceVoltmeterPerfor- 1-22.AccessoryEqUipmentAvailable1-2manceTests5-6 5-34.AdjustmentandCalibration.5-10 SectionPage5-36.MeterMechanicalZero IIINSTALLATION2-1Adjustment5-10 2-1.Introduction.2-15-38.MeterChopperFrequency 2-3.InitialInspection2-1Adjustment(

9、A8R3)5-10 2-5.PowerRequirements2-15-41.MainLoopChopperFrequency 2-7.GroundingRequirements2-1Adjustment(A8R20).5-12 2-10.Installation2-15-44.InternalZeroAdjustment 2-12.BenchMounting2-1(A4R13) .5-12 2-14.RackMounting.2-15-46.BalanceAdjustment(A4R6).5-12 2-16.RepackagingforShipment2-15-48.MeterLoopAdj

10、ustments.5-12 5-53.StandardVernierAdjustment SectionPage(A10R11).5-13 IIIOPERATINGINSTRUCTIONS3-15-55.MaximumCurrentLimit 3-1.Introduction.3-1Adjustment(A10R8) .5-13 3-3.AccuracySpecifications3-15-57.InternalAlignmentProcedure5-13 3-7.OperatingPrecautions3-15-63.VoltageSetDriftCorrection.5-15 3-9-.C

11、ontrols,Indicatorsand5-69.TroubleshootingProcedure5-17 Connectors3-15-72.TroubleshootingTrees.5-17 3-11.DCStandard3-55-76.LoopGainCheck.5-28 3-12.Description3-55-78.MeterLoopChopperCheck.5-28 3-14.OperatingPrecautions.3-55-80.MainLoopChopperCheck.5-28 3-16.Sensing.3-65-82.RepairProcedures5-29 3-24.G

12、uarding.3-75-84.ReplacementofFactorySelected 3-26.NegativeOutputs.3-7Components.5-29 3-31.UsingtheZeroControl3-75-104.ServicingEtchedCircuitBoards5-30 3-38.UsingtheCurrentLimitControl3-75-106.ServicingRotarySwitches5-30 3-41.DifferentialVoltmeter3-85-109.MainLoopFeedbackDivider 3-42.Description3-8Re

13、placement(A9R4through 3-45.OperatingProcedure.3-8A9R9)5-31 3-47.ZeroingExternalOffsetVoltages3-9 3-49.Guarding.3-10 SectionPage 3-55.Voltmeter.3-12 3-56.Description3-12 VIREPLACEABLEPARTS6-1 6-1.Introduction6-1 3-58.OperatingProcedure3-12 6-4.OrderingInformation6-1 3-60.Amplifier.3-13 3-62.PowerAmpl

14、ifier.3-13 6-6.Non-ListedParts6-1 3-67.VoltageAmplifier3-13 4-83. 4-99. Section IVTHEORYOFOPERATION 4-1.ModesofOperation. 4-3.Standard. . . . . 4-12.DifferentialVoltmeter. 4-22.Voltmeter. 4-24.CircuitDescription. 4-25.InputCircuits. 4-34.MainLoopVoltageFeedback Amplifier. ReferenceLoop MeterLoop. 01

15、794-.1 Page 4-1 4-1 4-1 4-2 4-3 4-3 4-3 4-4 4-8 4-9 SectionPage VIICIRCUITDIAGRAMS7-1/7-2 7-1.Introduction.7-1/7-2 7-3.BlockDiagrams7-1/7-2 7-5.FunctionalDiagram.7-1/7-2 7-7.SchematicDiagrams7-1/7-2 7-9.ComponentLocationDiagrams7-1/7-2 Appendix ACODELISTOFMANUFACTURERS BSALESANDSERVICEOFFICES CBUILD

16、ING A DCCALIBRATIONSYSTEM iii ListofTables ListofIllustrations Model740B LISTOFTABLES 5-3 5-6 5-9 5-9 Page 5-7. 5-8. 5-9. 5-10. 5-11. 5-12. 6-1. 6-2. Number 5-2.DCStandard-AccuracyandLinearity TestData. 5-3.OutputNoiseandHumTestData 5-4.LlVMandVMAccuracyTestData, 1 V - 1000 V 5-5.LlVMandVMAccuracyTe

17、stData, 1mV- 100mV. 5-6.ChangingthePaddingResistancewith JumperWires.5-15 ChangingthePaddingResistors.5-15 PreliminaryChecks.5-16 FrontPanelTroubleshooting.5-17/5-18 MainLoopTroubleshooting.5-21/5-22/5-23 MeterLoopTroubleshooting.5-25 ReferenceLoopTroubleshooting.5-27 MechanicalParts6-3 ReplaceableP

18、arts.6-16 3-12 3-12 3-13 3-13 4-1 4-2 4-3 5-0 Page 1-0/1-1 1-2 1-2 3-5 3-7 3-9 Number 1-1.Specifications. 1-2.AccessoryEquipmentSupplied. 1-3.AccessoryEquipmentAvailable 3-1.OutputTerminalConnections. 3-2.ZEROControlRange. 3-3.InputTerminalConnections 3-4.VMMode RANGEandSENSITIVITY Settings 3-5.Inpu

19、tTerminalConnections 3-6.PowerAmplifierOutputVoltage 3-7.RECORDEROUTPUTVoltageGain asaFunctionof RANGEandSENSI- TIVITY. 4-1.MainLoopGainCharacteristics 4-2.MainLoopGain(.VM) 4-3.MeterLoopGain(LlVMandVM) 5-1.RequiredTestEquipment. 5-4 5-5 5-6 5-7 5-7 5-8 1-0 3-0 3-0 3-10 3-11 3-11 5-2 5-4 5-26 3-10 O

20、FILLUSTRATIONS PageNumberPage 6-1.MechanicalParts. . . . . . . .6-2 7-1.DCVoltmeterandDifferentialVolt- meterBlockDiagram. . . . . . . 7-3/7-4 7-2.DCStandardBlockDiagram7-5 7-3.FunctionalandComponentLocation Diagram7-6/7-7/7-8/7-9 7-4.InputandOutputCableAssemblies SchematicDiagram. . . . . . . . . .

21、 7-10 7-5.InternalAlignmentSchematicand ComponentLocationDiagram 7-6.MeterAmplifier(p/oA2)Schematic andComponentLocationDiagram7-13/7-14 7-7.LowLevelAmplifier(A3)Schematic andComponentLocationDiagram7-15/7-16 7-8.OperationalFilterandDifferential Amplifier(A4)SchematicandCom- ponentLocationDiagram.7-

22、17/7-18 7-9.PulseWidthConverter,20 kHzClock andExternalCurrentLimit(A5) SchematicandComponentLocation Diagram7-19/7-20 7-10.GuardedPowerSupply(A6)Schematic andComponentLocationDiagram.7-21/7-22 7-11.PowerSwitchDriver,Internal CurrentLimitandUnguardedPower Supply(A7)SchematicandCom- ponentLocationDia

23、gram. . . . 7-23/7-24 7-12.ChopperNeonDrivers(A8)Schematic andComponentLocationDiagram.7-25/7-26 7-13.OvenHeaterand1 VReference Supply(p/oAI,p/oA2, A13) SchematicandComponentLocation Diagram7-27/7-28 7-14.VoltageSetandSensitivitySwitching (S2,S4thruS8)Schematicand ComponentLocationDiagram.7-29/7-30

24、LIST 5-4. 5-5. 5-6. 5-7. 5-8. 5-9. 3-1. 3-2. 3-3. 3-4. 3-5. 3-6. 3-7. 3-8. 5-10. 5-11. 5-12. 5-13. 5-14. 5-15. 5-16. 5-17. 3-10. 3-11. 5-1. 5-2. 5-3. Nwnber 1-1.Model740B DCStandard/Differential Voltmeter. OutputVoltageAccuracy,STDMode. VoltageReadingAccuracy,LlVMMode FrontandRearPanelControls,Indi-

25、 catorsandConnectors.3-2/3-3/3-4 LocalSensing. . . . . . . . . . . .3-6 RemoteSensing. . . . . . . . . .3-6 MaximumOutputCurrentCharacteristics3-8 SixthDigitLlVM3-9 MeasurementErrorCausedbyAC GroundCurrents. . . . . . . 3-9.MeasurementErrorCausedbyDC GroundCurrents. . . . . . . GuardingAgainstACGrou

26、ndCurrents. GuardingAgainstDCGroundCurrents. DCStandardAccuracyTest. . . . . CurrentLimitTest. . . . . . . . . LoadRegulationandOutputResistance Test. RFITest. InputResistanceTest. . . . . . SuperimposedACRejectionTest. ACCommonModeRejectionTest LlVMandVMAccuracyTest,1V - 1000 V LlVMandVMAccuracyTes

27、t, 1mV- 100mV. . . . . . . . .5-10 MeterLoopChopperWaveshape.5-10 InternalAdjustmentsandTestPoints5-11 MainLoopChopperWaveshape. .5-12 ReferenceSupplyCalibration. .5-14 FrontPanelTroubleshootingTree.5-16 MainLoopTroubleshootingTree.5-19/5-20 MeterLoopTroubleshootingTree5-24 ReferenceLoopTroubleshoot

28、ing Tree. iv01794-1 SectionI N ClnfC(:I.t vOlfollOt 11 Model740B ) Figure1-1.Model740B DCStandard/DifferentialVoltmeter Table1-1.Specifications DC STANDARD RANGES: OutputVoltage:0to 1000*voltsin4decaderanges withoutputsasfollows: oto1. 000000voltsin1jJ.Vsteps oto10.00000voltsin10jJ.Vsteps oto100.000

29、0voltsin100jJ.Vsteps oto1000. 000voltsin1 m Vsteps PERFORMANCERATING: Accuracy:(0.002%ofsetting+O.0004%ofrange) at230C10C,lessthan70%relativehumidity, constantload. Stability:Ratedaccuracyismetafter1hour warm-upperiod,witha30-daycalibration cycle. ShortTerm:1 ppm ofsetting+0.5ppm of range/hour;5ppm

30、ofsetting+1ppm ofrange/ day.100voltsoutput.) Temp.Coefficient:Lessthan(2ppm ofsetting or1ppmofrangewhicheverisgreater)per C;100Cto400C. OUTPUTCHARACTERISTICS: OutputCurrent:Currentlimitercontinuously adjustable5-50rnAnominal.Max.outputcur- rent,50rnAdecreasinglinearlyto20rnAat 1000voltsoutput. Outpu

31、tResistance:Lessthan(0.0002+0.0001 Eo)ohmsatDC. LoadRegulation:Lessthan(0.0005%+10jJ.V) change,noloadtofullload. LineRegulation:Lessthan(0.0005%ofsetting +O.OOOl%ofrange)for10%linevoltagechange. NoiseandHum:.01to1 Hz:lessthan1 ppm of range;1Hz to 1 MHz:100dBbelowfullscale or100jJ.Vrms,whicheverisgre

32、ater. 1-0 OutputTerminals:Plusandminusoutput,plus andminussense,circuitguard,andchassis ground.Bananajacksmountedonremote terminalbox(Accessory1l055B,furnished). Outputandsenseterminalsaresolidcopper, goldflashed.Amaximumof 500 Vdcmaybe appliedbetweenchassisgroundandguard orcircuitground. ZeroContro

33、lLimits:O. 001% ofrangenom- inal. Readout:5digitaldisplaytubesindicatefirst 5digits;meterdisplays6thdigit. DCDIFFERENTIALVOLTMETER VoltageRanges:1mVto 1000v*DC in 7de- caderanges. Resolution:Nullrangesgivefullscaleindi- cationof O. 01% ofrange.Max.resolution 1 ppmatfullscale.Max.usablenullsensi- tiv

34、ity:1jJ.Vfullscale. PERFORMANCERATING: Accuracy:(0.005%ofreading+0.0004%of range+1I).V)at230C 1C,lessthan70% relativehumidity. Stability:Ratedaccuracyismetaftera 1hour warm-upperiod,witha30-daycalibration cycle. Short-term:1ppm/hr.,5ppm/dayexclu- siveofzerodrift.(-100voltsinput.) Zerostability:(1ppm

35、 ofrange+2Il.V)/day. Temp.Coefficient:Lessthan(2ppm ofread- ing+1I).V)/0C,10Cto40C. LineRegulation:Lessthan(O.001%ofreading +2flV)changefor10%linevoltagechange. 01794-1 Model740B SECTIONI GENERALINFORMATION SectionI 1-1.INTRODUCTION. 1-2.Thissectioncontainsgeneralinformationabout theModel740B DCStan

36、dard/DifferentialVoltmeter. 1-3.DESCRIPTION. 1-4.TheHewlett-PackardModel740BisaprecIsIOn multifunctioninstrumentthatoperatesasadcstan- dardvoltagesource,a dcdifferentialvoltmeter,a highimpedancedcvoltmeteranda dcpowerandvoltage amplifier.Theinstrumentisdesignedforuseinboth thestandardslaboratoryandt

37、hefield. 1-5.DC STANDARD. 1-6.Whenusedasadcstandard,theModel740B providesoutputvoltagesfrom0to1000 Vin4decade ranges:1 V, 10 V,100 Vand1000 V.Theoutput voltageoneachrangecanbesetwith6-digitresolution. Table1-1.Specifications(Contd) INPUTCHARACTERISTICS: InputResistance:1010ohms100mVto1000 V ranges.

38、109ohmson10mVrange. 108ohmson1mVrange. Independentofnullcondition. SuperinlposedACNoiseRejection:Lessthan O.001%errorforacvoltagesabove60Hzequal toDCsignal(25 Vrmsmax.). EffectiveACCommonModeRejection:120dB at60 Hzwith1knunbalance. InputTerminals:Plus,minus,guard,andchas- sisground;Bananajacksmounte

39、donremote terminalBox.Plusandminusterminalsare solidcopper,goldflashed.500Vdcmaximum maybeconnectedbetweenchassisgroundand guardorcircuitground. HIGHIMPEDANCEVOLTMETER VoltageRanges:1/lVto1000*voltsendscalein 10zerocenteredranges.(1/lVto1 m Vranges obtainedbyusingnullsensitivitypushbuttons.) PERFORM

40、ANCERATING: Accuracy:(2%ofendscale+O.1/lV). INPUTCHARACTERISTICS: InputResistance:1010ohms100mVto1000 V raeges. 10ohmson 10mVrange. 108ohmson 1/lVto 1mV ranges. ZeroControlLimits:10/lVnominal. ZeroDrift:Lessthan2/lVperdayafter30 minutewarm-up. SuperimposedACRejection:Acvoltagesabove 60 Hz; 60dBgreat

41、erthanendscaleaffects readinglessthan2%(25 Vrmsmax.). RECORDEROUTPUT Adjustable0 to 1 Vdcat1 rnAforend scalemeterindication.Recordernega- tiveterminalcommonwithinputnegative terminal. 01794-1 AMPLIFIER VoltageGain:RecorderOutput:120dBmax. Outputterminals: 60dBon 1mVrange 40dBon 10mVrange 20dBon 100m

42、Vrange Unity on 1 Vto1000 Vranges PerformanceRating:(outputterminals) GainAccuracy:(O.OOl%+5ppmofrange+ 2 /lV)referredtoinput. Linearity:O. 002% onanyrange.(1mVand above) OutputCurrent:SameasDCStandard. Bandwidth:DCto0.2Hz. InputResistance:Sameast.VM. LineRegulation:LessthanO.0005%ofreading +2/lVref

43、erredtoinputfor10%linevoltage change. Noise:.01Hz to 1 Hz(referredtoinput) .5 /lVpk-pkat60dB1.0/lVpk-pkat40 dBgain. 3/lVpk - pkat20dBgain. Unitygain(1/lVrangeandabove)same asDCStandard. 1 Hz to 1 MHz: 1Vto1000 Vranges:same asDCStandard.Below1Vrange:1010S1onall rangesabove10mY)ismaintainedregardlesso

44、f whetherornotthevoltagedialsarenulled.Theinput circuitisfloatingandguarded,allowingaccurate measurementstobemadeunderconditionswhere groundloopsareaproblem. 1-9.mGHIMPEDANCEVOLTMETER. 1-10.TheModel740Bcanalsobeusedasa 2% floatingandguardeddcvoltmeterwith10voltageranges from1jlvto1000v.Inputresistan

45、ceis1010S1on allrangesabove10 mV.Themeasuredvoltageis indicatedonthemeter. 1-11.AMPLIFIER. 1-12.TheModel740Bcanbeusedasa dcpoweramp- lifierintheVoltmeterandDifferentialVoltmeter modesofoperationbyconnectingthesourcetothe inputterminalsandtakingtheoutputfromtheoutput terminals.Voltagegainisunityonthe

46、1 Vrangeand higher,butincreasesin20 dBstepsonthelower rangesto amaximumof 60dBonthe1mVrange. Outputcurrentcharacteristicsarethesameasthe DCStandardmodeandthehighinputresistancechar- acteristicsoftheVoltmeterandDifferentialVoltmeter modesareretained.Voltagegainaccuracyis(O.01% +5ppmofrange+2/lV). 1-1

47、3.TheModel740Bcanalsobeusedasavoltage amplifierintheVoltmeterandDifferentialVoltmeter modeswithupto 120 dB ofvoltagegainavailableat therearpanelRECORDEROUTPUTterminals. Voltageattheseterminalsisdirectlyproportionalto meterdeflectionandis0 to 1 V onallranges,l/J,V to 1000 V. 1-14.INTERNALADJUSTMENT.

48、1-15.Aninternalbridgingarrangement,requiringno externalequipment,allowsresistorsinthefirstand seconddecadesandtherangedividertoberatio matchedtocompensateforlongtermagingeffects. Thefrontpanelmeterservesasabridgenullindi- 1-2 Model740B catorandaninternalalignmentswitchsetsupthe bridge.Atotalof12adju

49、stmentsmatchthere- sistors.Theonlyotheradjustmentaffectingbasic instnm1entaccuracycaneasilybemadewithastan- dardcellorotherknownvoltagesource.Theinternal alignmentprocedureisoutlinedontheinstrumentin- ternalguardcoveranddescribedindetailinSectionV ofthismanual. 1-16.SPECIFICATIONS. 1-17.Table1-1liststhespecificationsfortheModel 740B.Specificationsarelistedbyinstrumentfunction. ThosespecificationslistedwithafunctionapplyLo thatfunctiononly. 1-18.INSTRUMENTIDENTIFICATION. 1-19.Hewlett-Packardusesatw