HP-428B-Manual-SNprefix-131 电路图.pdf
HP Archive This vintage Hewlett Packard document was preserved and distributed by Pleasevisituson the web! Scanned by on-line curator: Tony Gerbic * For FREE Distribution Only * RadioFans.CN 收音机爱 好者资料库 4288 CLIP-ONDC MILLIAMMETER OPERATINGANDSERVICEMANUAL JIll HEWLETTiIiPACKARD RadioFans.CN 收音机爱 好者资料库 01171-4 OPERATINGANDSERVICEMANUAL (HPPARTNO.00428-90002) MODEL428B CLIP-ONDCMILLIAMMETER SERIALSPREFIXED:131-,601- CopyrightHewlett-PackardCompany 1962 P.O.Box 301,Loveland,Colorado,80537U.S. A. Printed:OCT1966 RadioFans.CN 收音机爱 好者资料库 Model 428B TABLE OFCONTENTS TableofContents ListofIllustrationsandTables SectionPageSectionPage IGENERAL1-1IVTHEORY (Contd) 1-1.Introduction.1-14-25.DetectorGateAmplifier.4-2 1-4.OtherProbeHeads1-14-28.40-KCInput/AmplifierCircuit.4-3 1-7.InstrumentIdentification1-14-30.SynchronousDetectorandFilter ITPREPARATION FOR USE .2-1 (C24) .4-3 2-1.UnpackingandMechanicalInspection2-1 4-36.DCAmplifier4-4 2-4.OperationCheck.2-1 4-43.NegativeFeedbackCurrentCircuit4-4 4-45.40KCPhaseShifter.4-5 2-6.Installation.2-1 4-48.PowerSupply4-5 2-8.PowerRequirements2-1 2-10.Operationon 115or230 Volts.2-1VMAINTENANCE5-1 2-13.ThreeConductorPowerCable2-15-1.Introduction.5-1 2-15.Rack-MountModel.2-15-7.MechanicalZero-Set5-1 2-17.PreparationforStorageand Shipment2-15-9.CleaningofProbeJaws.5-1 2-20.Storage.2-15-11.TestEquipment.5-1 illOPERATION.3-1 5-13.TestInstruments.5-1 3-1.Turn-OnProcedure.3-1 5-14.AuxiliaryEquipment.5-1 3-4.MechanicalOperationofProbe.3-1 5-15.AdjustmentAfterTubeReplacement5-5 5-21.TroubleLocalization5-5 3-6.ElectricalZeroSet .3-1 5-26.Probe.5-5 3-10.DegaussingofProbeHead.3-1 5-28.PowerSupply.5-5 3-13.MeasurementPrecautions.3-1 3-15.Handling ofProbe3-1 5-29.Oscillator-HeadDriveAmplifier.5-5 5-30.HeadDrive5-6 3-21.MagneticFields3-2 5-31.SynchronousDetector5-6 3-28.ACFieldsandSuperimposedAC 5-32.DCAlnplifier.5-6 Current.3-2 3-32.EffectofInstrumentonCircuit3-2 5-33.AdjustmentAfterCurrentProbe 3-35.EffectofCircuitonInstrument3-2 Replacement.5-8 3-37.MeasurementPractices.3-3 5-35.CompleteAdjustmentProcedure5-8 3-38.PolarityofCurrent.3-3 5-37.FinalCheck.5-12 5-40.RangeCalibration.5-12 3-40.IncreasingtheAbsoluteSensitivity3-3 5-42.MeterTracking.5-13/5-14 3-42.CurrentCheck Loops.3-3 5-45.Loop Gain.5-13/5-14 3-44.Useof OutputJack.3-3 IVTHEORY.4-1 VIREPLACEABLEPARTS.6-1 6-1.Introduction.6-1 4-1.Introduction.4-1 6-4.OrderingInformation6-1 4-3.OverallOperation.4-1 4-9.CurrentProbe.4-1Appendix 4-19.20KCOscillator.4-2ACODE LISTOFMANUFACTURERS 4-23.HeadDriveAmplifier.4-2BSALESANDSERVICEOFFICES LIST OFILLUSTRATIONS Page 4-5 5-0 5-2 5-3 5-4 5-6 Number 1-1.IfjJModel 428BClip-OnMilliammeter. 1-2.VoltageandCurrentMeasurement 3-1.MeasurementProcedure. 3-2.TypicalPowerSupply. 3-3.ClipProbeAroundWire. 3-4.IncreasingtheAbsoluteSensitivity 4-1.BlockDiagramModel 428B 4-2.SimplifiedBlockDiagram. . . 4-3.MechanicalFluxGate . . . . . 4-4.SaturableFluxGate. . . . . . 4-5.CurrentProbeBridgeCircuit. 4-6.SynchronousDetector. 4-7.Change of Output ofSynchronous DetectorwithPhase. . . 4-8.FeedbackCurrentCircuit. Page 1-1 1-1 3-0 3-2 3-3 3-3 4-0 4-1 4-1 4-2 4-2 4-3 4-4 4-5 Number 4-9.40KCPhaseShifter. 5-1.CleaningProbeJaws. 5-2.ElectricalZero-Set. 5-3.DCCurrentIndication. 5-4.ACOverload. 5-5.DetectorPhaseAdjustmentSetup. 5-6.DetectorPhaseAdjustment Waveforms. . . . . . . . . .5-7 5-7.TroubleLocalizationWaveforms5-8 5-8.Exploded View ofProbe. . . . 5-11 5-9.OutputCalibrationTestSetup.5-12 5-10.LeftSideInternalView Model428B.5-12 5-11.RightSideInternalViewModel428B.5-13/5-14 5-12.428BSchematic(Oscillator,Power Supply,andAmplifier)5-15/5-16 LIST OF TABLES Number 1-1.Specifications. . . . . . . . . . 5-1.TubeorTransistorReplace- ment. 01171-4 Page 1-0 .5-5 Number 5-2.AdjustmentProcedure. 6-1.ReferenceDesignationIndex. 6-2.ReplaceableParts. . . . . Page 5-8 6-2 6-8 iii SectionI Table1-1 Model428B Table1-1.Specifications WEIGHT:CabinetMount:Net19lbs RackMount:Net 24lbs PROBETIPSIZE: Approximately1/2in.by21/32in.Aperture diameter5/32in. LD-S-507 TOP 3 .=i9.-i DIMENSIONS: CabinetMount:7-1/2in.wide,11-1/2in.high, 14-1/4in.deep. 3 i6 RackMount: 5 HOLE32DIA. CURRENT RANGE: 1mato10amperes.Nine fullscaleranges from1mato10amperesina1,3, 10, 30. sequence. PROBEINDUCTANCE: LessthanO.5J.lh.Nonoticeableloading,even upto1mc. NOISELEVEL: LessthanO.015ma ACREJECTION: ACwithpeakvaluelessthanfullscaleaffects meteraccuracylessthan2%atfrequencies above 5cpsanddifferentfromthecarrier(40kc)and itsharmonics,(on10ampererangeacislimited to4amperespeak). OUTPUT: Approximately1.5voltsand1rnamaxforfull scale;100-ohmsource.Variablelinearoutput levelwithswitchprovisionforcalibrated1volt (correspondstofullscaledeflection).Bandwidth dcto400cps. ACCURACY:00 3%offullscalefrom0 Cto+55 C 0.1ma PROBEINDUCED VOLTAGE: Lessthan15mvpeak(at20kcandharmonics) Below 5cpstotaiinstantaneouscurrentmustnot exceedfullscale. ACCESSORIES AVAILABLE: Model3528ALargeApertureProbe Model3529AMagnetometerProbe PROBE INSULATION: 300voltsmaximum,dcorpeak PONER: 115or230volts10%,50to60cps,approximately 70watts OPTIONS: 01.Model3528ACurrentProbe(Aperture, 2-9/16in.)inlieuof Model 428A-21AProbe normallysupplied 02.Model3529AMagnetometerProbeinlieu of Model 428A-21AProbe 1-0 01171-4 Model428B SECTIONI GENERAL SectionI Paragraphs1-1to1-8 1-1.INTRODUCTION. 1-2.Ther5ffJModel 428BClip-OnMilliammetermea- uresthemagneticfield,whichexistsaroundthewire carryingdccurrent.Operatingtheinstrumentis simple.Afterzerosetting,thetwojawsoftheprobe areclampedaroundwire(arrowonprobeheadindi- catesdirectionofconventionalcurrentflow)andthe meterwillindicatethecurrent. 1-3.Thereareninecurrentrangesstartingfrom 1 rnato10ampfullscaledeflection.Thesensitivity canbeincreasedevenfurtherbyloopingthewire severaltimesthroughtheopeningintheprobe.The currentindicationisvirtuallyinsensitivetosuper- imposedacsignalsandtheseriesloadingofthecircuit islessthan0.5/lh.Alargeamountoffeedbackpro- videsgreatstability.WiththeModel 428Bcurrents canbemeasuredaseasilyasmeasuringvoltageswith a voltmeter. 1-4.OTHER PROBE HEADS. 1-5.Otherprobeheadsareavailabletoextendthe usefulnessofyourClip-OnDCMilliammeter.Write tothefactoryforfurtherinformation.Atthetimeof publicationofthismanualthefollowingaccessory probeheadswereavailable: a.r5ffJModel 3528ALargeAperture(2-1/2inchprobe head). b.r5ffJModel3529AMagnetometer(1gauss=1amp). 1-6.Writethefactorystatingyourcompletere- quirementsforinformationconcerningspecialappli- cations. 1-7.INSTRUMENTIDENTIFICATION. 1-8.Hewlett-Packardusesatwo-sectioneight-digit serialnumber(000-00000).Ifthefirstthreedigits Usualclip-onvoltmetermeasurementof voltagewithoutbreakingcircuit oftheserialnumberonyourinstrumntdo notagree withthoseonthetitlepageofthimanual,ch8nge sheetssuppliedwiththemanualwilldefinedifferences betweenyourinstrumentand thModel-!28Bdescribed inthismanual. Figure1-1.cIifJModel 428BClip-OnMilliammcwr 10-5-512 Clip-onmeasurementofcurrentwith rtf!;Model 428B withoutbreakingcircuit 01171-1 Figure1-2.VoltageandCurrentMeasurement 1-1/1-2 Model4288 SECTIONII PREPARATIONFORUSE SectionII Paragraphs2-1to 2-21 2-1.UNPACKINGANDMECHANICAL INSPECTION. 2-2.Inspectinstrumentforsignsofdamageincurred inshipment.Thisinstrumentshouldbetestedassoon asitisreceived.Ifitfailstooperateproperly,or isdamagedin any way, aclaimshould befiledwith thecarrier.A fullreportofthedamageshouldbe obtained by theclaimagent,andthisreportshouldbe forwardedtous.Wewillthenadviseyou ofthe dispositionto bemadeoftheequipmentandarrange forrepairorreplacement.Includemodelnumber andserialnumberwhenreferringtothisinstrument foranyreason. 2-3.Hewlett-PackardCompanywarrantseachinstru- mentmanufacturedbythemto befreefromdefects inmaterialandworkmanship.Ourliabilityunder thiswarrantyislimitedtoservicingoradjustingany instrumentreturnedtothefactoryforthatpurpose andtoreplaceanydefectivepartsthereof.Any damageto theinstrumentuponreceiptisduetothe carrier.Fileaclaimwith thecarrierasinstructed intheprecedingparagraph. 2-4.OPERATIONCHECK. 2-5.Thisinstrumentshouldbecheckedassoonas itisreceivedtodeterminethatitselectricalcharac- teristicshave not beendamagedinshipment.Referto theFIALCHECK,paragraph5-37attheend ofthis manual. 2-6.INSTALLATION. 2-7.TheModel4288dependsonnaturalaircon- vection cooling.Thereforeitisadvisabletoplace theinstrumentonthetableorworkbenchsothatthe aircancirculatefreelythroughtheinstrument. CAUTIO Thecurrentprobeshould not beexposedto temperaturesexceeding550C (131OF)ashigh temperaturesseriouslyaffecttheheadofthe probe,resultinginunbalanceandeventual damagetotheprobe.Donotleaveprobeon top oftheModel 428B(oranyotherhotplace). 2-8.POWERREQUIREMENTS. 2-9.Powerrequirementsaregiven inSpecifications tableatthefrontofthismanual. 2-10.OPERATIONON115OR230VOLTS. 2-11.Thisinstrumentmaybeusedwitheithera lIS-voltor230-voltsupplywith afrequencyof 50 to 01171-1 60cps,singlephase.Thisinstrumentisshipped fromthefactoryreadyforoperationfromalIS-volt sourceunlessotherwiseindicated. 2-12.Tooperatefroma230-voltsourcethe115-230 switchontherearapronmustbeflipped to 230.First turntheinstrumentofforpullthepowercablefrom thesocket.Placeapointedtool,suchasthesharp- enedend of apencil,intheslotoftheswitchand pull down.Replacethefusewiththeone given intable 6-1for230-voltoperation. 2-13.THREECONDUCTORPOWERCABLE. 2-14.Thethree-conductorpowercablesuppliedwith theinstrumentisterminatedinapolarized,three- prongmaleconnectorrecommendedby theNational ElectricalManufacturersAssociation(NEMA).The thirdconductorgroundstheinstrumentchassisforthe PROTECTION OFTHEOPERATING PERSONNEL. Whenusingathree-prongtotwo-prongadapterground thirdlead(greenwire)externally. 2-15.RACK-MOUNTMODEL. 2-16.Thisinstrumentisalsoavailablein arack- mountversioninadditiontothecabinetmodelshown inthismanual.Therack-mountversionisidentical electricallyandsimilarphysicallyexceptthatthe Degausserhasbeenmovedtothefrontpanelfor greaterconvenience. 2-17.PREPARATIONFORSTORAGE ANDSHIPMENT. 2-18.Thebestmethodforpackingthisinstrumentis intheoriginalshippingcartonwiththeoriginalfillers packedinthesamemanneraswhenreceivedfromthe factory.Therefore,when unpacking notecarefully themethodof packingandsavetheoriginalpacking materialforpossiblefuturere-use. 2-19.Iftheoriginalpackingmaterialisnotavailable anditisdesiredtopackagetheinstrumentforstorage orshipment,firstwraptheinstrumentinheavykraft papertoavoidscratchingthepaint.Thenpackin a cardboardcartonwith aburstingstrengthofatleast 150lbpersquareinch.Padtheinstrumentonall sideswithatleast2inchesofrubberizedhairorat least4inchesof tightlypackedexcelsior. 2-20.STORAGE. 2-21.0specialprecautionsarenecessaryinstorage excepttheusualprotectionagainstmechanicaldamage, saltair,etc. 2-1 SectionIII Figure3-1 Model 428B 4288 1.Turnonpowerand allowapproximately2 minuteswarmuptime. 2.Checkclosureofprobejaws.Incomplete closureofthejawsisindicatedbyexcessive zero-shiftonthe1 rnacurrentrangewhen probeisrotatedinearthsmagneticfield. Cleanprobejawsifnecessary(seeparagraph 5-9,CleaningProbeJaws). 3.SetRANGEswitchto1 rna.Zero-setinstru- mentwith ZEROcontrol. 4.SetRANGEswitchtoarangethatishigherthan theanticipatedcurrenttoberead. 5.Clipprobejawsaroundwirecarryingdccur- rent,pointingthearrowontheprobeinthe directionof conventionalcurrent(seearrows infigureabove). 6.Readcurrentonmeter. NOTE AfteruseoftheModel 428B onthe1thru10AMPRANGEdegausstheprobe head(Paragraph3-10)ifzerosetcannotbeaccomplished. Figure3-1.MeasurementProcedure 3-0 01171-2 Model 428B 3-1.TURN-ONPROCEDURE. SectionIII Paragraphs3-1to3-18 SECTIONIII OPERATION 3-10.DEGAUSSING OF PROBE HEAD. 3-2.Beforeoperatingtheinstrument,checktheme- chanicalzeropositionofthemeter.Forthemechani- calzerosettingofthemetermovement,referto paragraph5-7. CAUTION BesuretheRANGEswitchison 1 AMPor lessbeforeturningonthisinstrument.Other- wisetheprobemaybecomemagnetizedand needdegaussingbeforeusing. 3-3.Figure3-1illustratesthemeasurementpro- cedurefortheinstrument. Note Readparagraph3-13,MeasurementPrecau- tions,beforeoperatingtheinstrumentforthe firsttime. 3-4.MECHANICALOPERATIONOF PROBE. 3-5.Theprobejawsareopened bysimplysqueezing togetherthetwoflangesontheprobebody.Aninternal springreturnsthejawstotheirproperpositionwhen theflangesarereleased. CAUTION Do NOTreleasetheflangesabruptlysothat thejawssnaptogether.Thismaycause binding andzero-shift. 3-6.ELECTRICALZEROSET. 3-7.Iftheinstrumentcannotbezerosetelectrically (with ZEROcontrol)therearetwoprobablecauses: 1)Incompleteclosureofprobejaws,2)Magnetization ofprobehead. 3-8.INCOMPLETECLOSUREOFPROBE JAWS. Dustdepositson thelappedsurfacesoftheprobe jawscreateanairgap.Ifthejawsarenotcom- pletelyclosedtheearthsmagneticfield willaffect thereading.WiththeRANGEswitchat1ma,ro- tationoftheclosedprobeshould notvarythezero- setmorethan 0.1maoCleaningofthejawswill restoreproperoperationconditions(seeparagraph 5-9,CleaningofProbeJaws). 3-9.MAGNETIZATION OF PROBE HEAD.Magnetic shieldsprotecttheprobeheadfromstraymagnetic fields.However,excessivedccurrents(suchas shortcircuitdischargecurrentsfromelectrolytic capacitors,etc.)willmagnetizetheprobe.For demagnetizationofprobehead,seeparagraph3-10, DegaussingofProbeHead. 01171-2 3-11.Fordemagnetizingtheprobeproceedasfollows: a.Insertprobeintodegausserattherearofthein- strument(locatedonfrontpanelof rack-mountmodels) witharrowonprobeinsamepositionasarrowmarked onchassis. b.DepressdegausserswitchS3toenergizede- gausser. c.Withdrawprobeveryslowlyforthefirstfew incheswhiledepressingthedegausserswitchuntil probeisremovedapproximatelyone foot. d.Zeroinstrumenton 1marangewith ZEROcontrol. 3-12.Undernormaloperatingconditionsdegaussing maybenecessaryaftermeasuringcurrentonthe1thru 10AMPRANGE. CAUTION Thedegausserisdesignedforintermittent operationonly.Itmaybeoperatedfor periodsup tothreeminutescontinuously withoutexcessiveheating.Normaldegauss- ingtakesonly about 10seconds. 3-13. MEASUREMENT PRECAUTIONS. 3-14.Itisrecommendedthatthisparagraphberead carefullybeforeoperatingtheModel 428BClip-On Milliammeterforthefirsttime.Ingeneral,currents canbemeasuredwiththeModel 428Basconveniently asvoltageswith avacuumtubevoltmeter.However, therearesituationsthatcancauseinaccuratecurrent readings.Thesesituationsaredescribedasfollows: Handling ofProbe MagneticFields ACFieldsandSuperimposedACCurrents EffectofInstrumentonCircuit EffectofCircuitonInstrument 3-15.HANDLING OFPROBE. 3-16.MECHANICAL HANDLING OFPROBE.Do not closethejaws bylettinggooftheprobeflangesabruptly (snapping),asthismaymagnetizethehead.Also, do notdroptheprobe.Thejawsaremadefroman alkyd plasticmaterial,whichisverydurableundernormal use,butisnotmadetowithstandtheshockofdropping. 3-17.Forthecleaningoftheprobejaws,referto paragraph5-9. 3-18.EXPOSURETOHIGHTEMPERATURE.The probemustnotbesubjectedtotemperaturesexceeding 1310F (550C),ashighertemperaturesaffectthecali- brationandpermanentlyincreasethesusceptibilityto strayfields.Donotlaytheprobeon top ofthecabinet, ashotairfromtheinstrumentcanheattheprobe. 3-1 SectionIII Paragraphs3-19to3-36 3-19.VOLTAGE INSULATION.Itispreferableto cliptheprobearoundinsulatedwir
