Nagra-IVSJ-tape-sm 维修电路原理图.pdf

RadioFans.CN 收音机爱 好者资料库TAPE/DIRECT,LINE&PHONES:switchingof the playbacksignal o ofthe directsignal on theline outputs,headphonesand loudspeaker;switchinactive on TESTTAPE/DIRECT,METER:switchingof the playbacksignal or of the directsignalon thecircuitof rIleter14; this switchcannotbe lockedon TAPEPOWER:powerselectorswitchi.e. built-inbatteriesor accumulatorsorexternalpower supplyconnectedto plug 48Main functionswitchSTOP: recorderat standstillTEST:power soppliedto all circuits,exceptrecord and eraseRECORD:power suppliedto all circuits and the motor;record and erase onthe 3 tracksPLAYBACK:the recordedsignal can be heard on the headphonesand is fedto the line outputsof connectors41, 42,43,45and 46 when switch1 is onTAPE(or onDIRECTif the outputsignal is reintroducedinto the directchain. see 42)PLA YBACK with Loudspeaker:playbackof tape using loudspeakerLIGHT;meter14lightsupmomentarily:remainsilluminatedwhenthebuttonis turnedto the rightoMain attenuatorCHANNEL2: in steps of 10 dB for channel2,IowertrackVernier attenuatorCHANNE L 2; in steps of 1dB for channel1Main attenuatorCHANN.E L 1: in steps of 10 dB for channelI, uppertrackVernier attenuatorCHANNE L 1: in steps of 1dB for channel1dBscale:forthemicrophoneinputs,in relationto thesoundpressurelevel 0.OOO2pbar=0 dBvoltage scale; effectivevoltage appliedto the line input, which gives a readingof OdB on the AVERAGEscale of meter14REF.OSCILLATOR:switchedonwhenthebuttonis depressed,thereferenceoscillatorsuppliesa +10 dB signal to the direct amplifieron eachchannel,after the attenuatorLINE/MIKE:line or microphoneinput selector,channel2LINE/MIKE:line or microphoneinput selector,channellFI LTERS:6-positionfilter selectorswitch for channell:HPhighpassL1N.linearWE IGHTINGA, B, C, Dweightingcurves A, B, C and DMETERFUNCTION:six-positionselectorswitch for meter 14lEVEL.AVERAGEFAST: on the AVERAGEdecibel scale, average valueof the soundlevel, fast characteristic,red needle for channelI, green needlefor channel2lEVEL.AVERAGESLOW;thesameasAVERAGEFAST,butslowcharacteristicLEVEL, PEAK: on thePEAK decibelscale, peak value of the soundlevel,channelsas aboveBATT.: on the BATTERIESscale, batteryor accumulatorcheckRed needle:batteryvoltage per cell (VOLTS/CELL)Green needle:voltage requiredby the motor,with the same reductionfactoras batteryvoltagePILOT8oCUE:Greenneedle:on thePILOT0 to100% scale, overall frequencydeviationcausedby the pilotand CUE signals,100% on the scale correspondingto adeviationof 40%Red needle:on the PILOT +4 to -4% scale, frequencyshift, as determinedbythe built-in OFMS frequencymeter, betweena signal recordedor played backon the thirdtrackand an internalreferencePosition M:Green needle:same as PILOT&CUERed needle:on the 0 to 100% scale, currentthroughthe motor,100% on thescale correspondingto 250 mACDFll TERS:filter selectorswitch for channel2. identicalto IIMeter:indicatessound level and checkingfunctionsaccordingto the positionof selectorswitch12IIPILOT:indicatorwhich showsa whitelonewhen frequencyand amplitudeof the pilot signal are correctISPEED&POWER:indicatorwhich shows a whitelonewhen the followingthree conditionsare fulfilled:-power supply voltage higherthan the maximumadmissiblevalue-motorregulationwithinthe correctoperatingrangetachometricspeedfluctuationsnotexceedinqthemaximumvalueIIPHONES:connectorfor monoheadphones,impedance25 to 600nCHANNEL,PHONES&L.S.:channelselectorfor listening with headphonesand loudspeakerLEVEL, PHONES:adjustmentof the headphonesvolumeTape speed selectorswitchIS=38.1 cmls7/,=19.05cm/sII3% .=9.525 cm/s1h=3.81cm/sIBIAS: 5positionbias selectorswitchPinch-wheel6)Fast wind switch:REW.Irewindwith main switch 4 in any positionexceptSTOP, lever 32 in disengage positionfastwindwhenmainswitch4onPLAYBACKwith LoudspeakerISupplyreelTensionroller of the supplV reelErase headStabilizerroller with 50 or 60 Hz stroboscopeRecordinghead tracks 1 and 2e.Recordingand playbackhead track 3Playbackhead tracks1 and 2CDCapstan3positionlever controllingthe pinch-wheeland tape guicles:. -lever pulledto theleft:for threadingthetape(rewindpossiblein thisposition)-lever at 45to the edgeof thetape-deck:motorrunning,but tape notmoving-lever pushedbackwards:tape runningTensionroller of the take-upreelTakeup reel6)RECORDINGEOUALIZA TION ADJUSTMENTIIIIIIIRadioFans.CN 收音机爱 好者资料库L-JJl-jI JIJJIJ=.-.LDirect analysis of sound signalsUsed solely as an amplifier the NAGRA IV-SJ is aprecisionsoundlevel meter, which operateswithany calibratedmicrophonecartridge.The soundpressure measurementsmust be taken in relation tothe0dB referencelevel, which correspondsto apressureof 0.0002ubar, i.e. 20J.lN/m2or 20 J.lPa.This level coincidesin practice with the audibilitythresholdof the human ear at1kHz; at this fre-quency, the sound level can be expressed in phones,the phones value being equal to the dB value readin relation to the 0.0002 /-Ibarreference.The frequencyresponseof the humanear is notlinear and depends very much on the sound level; asound level meter must thereforeinclude weightingfilters which modify the values measured in accor-dancewithcertaincriteria,so thattheycan beinterpretedin relation to the subjective impressionfelt by the humanear.There are three standardweighting curves, A, BandC.Curve A is used forlow and mediumsoundlevels, which are the sub-ject of mostanalyses;curvesBandC relate tohigher levels.Curve D relates to contour-linesofperceivednoisiness,in particularwith noise pro-ducedby aviation:this weightingis used for themeasurementof soundswhichcause annoyancein general.Curves A, B, G and D are shown afterthe specifications.Thesoundlevel measuredis shownon a dualgalvanometer.withone needleper channel.Itsmeasuringcircuitdeterminesthe average value ofthe signal onRMSandits peak value onPEAK,withdifferentdynamiccharacteristicsinrelationto theintegrationtime.OnRMSFAST integrationtime is 200 ms: a signal at1kHzlasting 200 ms gives a reading1dB lower than thatwhich would correspondto the steady signal.OnRMSSLOW, integrationtime is 500 ms anda signal lasting 500 ms gives a reading 4 dB belowthat which would correspondto the steady signal.These two integrationtimes are in accordance withINSTRUCTION MANUALIMeasurementstheGEl standard179 forprecrsionsoundlevelmeters.Naturally,any signal which is shorter thanthe integrationtime will be shownbelowits realvalue.Foranalysisof pulsesignalsor strongtransientsa moreusefulreadingis obtainedonPEAK, i.e. peak value with an integrationtime ofonly5ms.This very fast reading cannotbe usedbecauseit causes visual fatigue:in order to over-come this disadvantagethe measuring circuit holdsthe signal for about one second, therebyincreasingthe fall time of the needle.Recording and playback of the sound signalsInallcaseswheredirect.measurementis notsufficientfor studyingthe signals picked up by themicrophone,these signals can be recorded on mag-netictapeand analyzedlater in thelaboratory.While the two tracks used for direct recording arein use, the thirdtrackCIOrecordF Msignals forsynchronization,a commentary,or a measuring-signal fromD.C. up to 4 kHz.The threetracksthus store signals in fully-synchronizedform, whichis an importantfactor for analysis.However, this storageis restrictedto some extentdue to thelimitationsof presentmagnetictapes.Theselimitationsconcernthefollowingcharac-teristics in particular:the response curveAttenuationat the upper and lower extremesofthe spectrum depends on the speed used.Very lowfrequencysignals, which are difficultto play backwith a small reproducehead, shouldbe analyzedby frequencytransposition.distortionThis increases very rapidly as soon as the maximumrecordinglevel is exceeded,and tapesaturationoccurs,generatingharmonicfrequencies(inparticular2nd and 3rd harmonics), which falsify theanalysis of the signals.IcrosstalkThe juxtapositionof the two channelsinside therecordinghead andthe playbackheadproducescrosstalk.This is the ratio, at a playback amplifieroutput.between the wanted signal and the unwan-tedsignalfromtheotherchannel.Crosstalkincreases at high frequencies.IIThe maximumpeak level, which correspondsto atapefluxof32 mM/mm,is reachedwhenthemeasuringinstrumentshows+10dBontheRMSscale and+20dB on the PEAK scale.These two values are given in relation to the soundpressurereferencelevel0 dB=20 pPaor0.0002J.1bar.OnRMStheintegrationtimeofthemeasuringcircuitis long enoughnot to indicateshortpulses at their exact value and risk exceedingthemaximumrecordinglevel, therebysaturatingthe tape.That is why, onRMS, the maxi-mum level is given at+10dB: the10dB lead avoidsthe signals with strong pulse content saturatingthetape too Quickly.In all cases wherethenatureof a signal is notobviousit should be recorded with the measuringcircuiton PEAK, which is the only way to makethepeak value of very short pulses visible and toavoid their exceeding the maximum recording level.FrequencytranspositionPlaybackspeedmay be differentfromrecordingspeed:this producesa frequencytranspositionofthe signals recordedwithin the ratio of these twospeeds.Since the response curve in thelow fre-quenciesis limited to25Hz on playback only, it ispossible,if the tape transportspeed is ten timesfaster on playback than on recording, to play backfrequencieswhichare ten times. lower.Thus, a2.5Hz signal recordedat1.5ips will have a frequencyof25Hz if it is playedbackat15ips(transposition1: 10), and can be analyzed easily byconventionalequipment.In the same way, thetimeneededto analyzesignals whichvary veryslowly is reducedin the same ratio by this process.Conversely.it is possible to analyze in more detaila signal whichvaries rapidlyby playingit backmore slowlythanit was recorded.However,inbothcases, care must be taken that the transposi-tiondoes not alter the signals in any way, takinginto accountthe limitationsof the frequencyres-ponse at the speeds used.IIIIIIIIIIMaximum frequency deviation tfoFrequencyresponse at-3 dBSignal-to-noise ratio for deviationof 20%45%oto 4 kHz44dBPeak-to-peakinputvoltage for deviation of 20%PILOT2_8 VCUE2.0 VIOPERATINGCONDITIONSTemperaturewith manganese batteriesIwith externalpower- 4to+160F-20to+71C-67 to +1600F-55 to+71CIThe recorderfunctionscorrectlyin any position.IJI)1htWei21In2 curveAdBFfequencylEe Recommendation179NGRAIV.sJRtI.tITolrnnToler.neeRespomelimitllImln+10H,dBdBdB2050.5,.!325- . 7:!:2.S031,5-39.4oJ.,/.40-34.6oJ.,./!-.SO-30.2oJ.,./-r-.31.5-17.11312.40-14.20312./,SO-u.s03t2./63- 9.30312-10eo-7.412:1:1.6/100- 5.e.,.,120- 42.,11/ISO- 3-20200- 2.,etV260-1.311316- D.e.,11-30/-0.51111600- 0.3.,.,830- 0.1.,118000tI11, GOD0at1112600.,.,-401e000.,.,2000- O.t112500- D.2.,113160- 0.114000- 0.71111-506000-12.11.5118_o1.8.1.5-2.,8000-a1-t.fI-3.11.510000- 4.2-4i1.612500- 6.1+3-611.618000- 8.4+3-il,6Hz20000-11.1+3-80200500100031508000125002031,5 50100315800120050001000020000_.-._-_.-rtlnIIIIJIIIJIIIJ2.4.Connectionof Brliel&Kjaer AmplifiersfittedwithBrliel&KjaerMicrophoneCartridgesB&KCARTRIDGEB&KPREAMPLIFIER-1QJIIIL-l:o.1T-=-=1IIQSJA-BK=iJJ=JThe followingtypes of cartridges-h;4133,4134,4149and4163-1 ;4144,4145,4146and4161-1,4;4135and 4136-1/8;4 138can be fittedto the followingtypes of preamplifiers:-1,1/2,1,4:2615-12,1,4 ,1/8:2614-1,12,1,4,1/8:2619-1: 2627, 2612 and 2613-1,4,%:2618The cartridgescan be fitteddirectlyontothe pre-amplifierswhen the diametersmatch;if they do notmatch,a mechanicaladaptercanbe used.TheoutputplugofthepreamplifierscrewsintotheOSJPadapterandtheplugofthepreamplifieradapter fits into microphoneconnector37:selector10 should be on MI KE.Therecordershouldbe fittedwiththe QSJA-BKmicrophoneamplifierand the QSJC universal powersupply.These circuitscan be installedas describedintheprecedingparagraph,Signals and VoltagesChassis connectorexternalside or plugsolderingside+200Y+120V.Jr -L_,-10G,-r-GND+12,6V2.5.Connectionof Sennheiser MKH 110 MeasuringMicrophoneThe MKH 110 microphoneconsists of a capacitorcartridgeand an electroniccircuitwitha low impe-dance output;microphonesensitivityis 2 mVIMbar.It shouldbe connectedtomicrophoneconnector37by the QCJ-MKHcable; selector10 shouldbe onMIKE_The recordershouldbe fittedwiththe QSJA-MKHmicrophoneamplifier,whichalso supplies the vol-tage for the microphone.Installationof aSJA-MKHAmplifierLockthe lid of the recorder,turn screws 50 severaltimes and open the case to its full extent.Unscrewthe connectorbetween the microphoneinputwiringand the case interconnectionboard.Plug in and fixthisconnectortothemicrophoneamplifierandsecure the latter to the case interconnectionboard.Unscrewthe level adapterboard.Place the shieldin positionand fixit undertile groundcombandundera nutscrewedontoone of the twohingefixingscrews (this screw should be longer - M3x8).Reinstallthe level adapter board.Signals and VoltagesChassis connectorexternalside or plugsolderingside-.,.-GNO-8Y-SIGNAL-10G-,I,IIIIII3.DIRECTMEASUREMENTOF SIGNALS3.1.Position of the ControlsSet switch1 on DIRECT: switch 2, which cannotbe locked in position,remains on DIRECT.Turnmain selectorswitch 4 to TEST: the circuits arethen switchedon and will stabilize after about 10seconds.3.2.Selection of Measuring CircuitSet the METER FUNCTION switch on one of theLEVEL positions:- RMS FAST: average valu of the signal on the RMSscale of meter14,integrationtime 200 ms.-RMSSLOW: averagevalue of thesignal on thesame scale, butintegrationtime 500 ms.-PEAK:peakvalue of thesignal, onthePEAK scale of meter14, integrationtime5 ms, witha memorycircuitholding thesignal for about1second.The measuringcircuitof the recordershould beselectedin accordancewiththe criteriagiven inSection3.3.3.Adjustmentof the Monitoring CircuitThe signals can be monitoredon the headphoneswith switch4in any position and with the built-inloudspeakeronPLAYBACKwithLoudspeaker(see 6.).Themonoheadphones,impedance50 to 600n.plug into jack 17.The requiredchannelcan beselected with switch18and the loudness regulatedby potentiometer19,which can be adjusted with ascrewdriver.3.4.Choice of Sensitivity3.4.1.Highlevel Signals on the Line InputSet selector10 on LINE, turnmain attenuator7fully to the left, or on GND, set vernier attenuator7Aon0dB (CAL.),Switchon the signal source connectedto the lineinput.While watching meter 14, turn main attenua-tor 7 totheright untilthered needle makes avisible movement.Calculate the value measured asdescribed in paragraph 3.6.1.3.4.2.High-level Signals on the MicrophoneInputSame procedureas in the preceding paragraph, butwith selector10on MIKE.3.4.3.Lowlevel Signals on the MicrophoneInputQSJA-BK AMPLIFIERWith selector10on MIKE, set vernier attenuator7Aon0dBTurn the cartridge type selector 40 to the positionwhich correspondsto the diameter of the cartridgeused.On1f.t thepositionsof gain selector39become +40. +60 and +90dB, values inscribed in acircle.Turn attenuator7to +20 dB and watchmeter14.If theneedlemoves noticeablybeyond+20 dBPEAK or +10 dBRMS,turnswitch39to+80 dB.If the needle is clearly below 0 dB, turnswitch 39 to +40 dB. Calculate the value measuredand take into accountthe restrictionsdescribedinparagraph3.6.3.QSJA-MKH AMPLIFIERT