Nagra-IVSJ-tape-sm 电路图 维修手册.pdf

RadioFans.CN 收音机爱 好者资料库 TAPE/DIRECT,LINEswitch inactive on TEST TAPE/DIRECT,METER:switchingof the playbacksignal or of the direct signalon thecircuitof rIleter14; this switchcannotbe lockedon TAPE POWER:powerselectorswitchi.e. built-inbatteriesor accumulatorsor externalpower supplyconnectedto plug 48 Main functionswitch STOP: recorderat standstill TEST:power soppliedto all circuits,exceptrecord and erase RECORD:power suppliedto all circuits and the motor;record and erase on the 3 tracks PLAYBACK:the recordedsignal can be heard on the headphonesand is fed to the line outputsof connectors41, 42,43,45and 46 when switch1 is on TAPE(or onDIRECTif the outputsignal is reintroducedinto the direct chain. see 42) PLA YBACK with Loudspeaker:playbackof tape using loudspeaker LIGHT;meter14lightsupmomentarily:remainsilluminatedwhenthe buttonis turnedto the right oMain attenuatorCHANNEL2: in steps of 10 dB for channel2,Iowertrack Vernier attenuatorCHANNE L 2; in steps of 1dB for channel1 Main attenuatorCHANN.E L 1: in steps of 10 dB for channelI, uppertrack Vernier attenuatorCHANNE L 1: in steps of 1dB for channel1 dBscale:forthemicrophoneinputs,in relationto thesoundpressure level 0.OOO2pbar=0 dB voltage scale; effectivevoltage appliedto the line input, which gives a reading of OdB on the AVERAGEscale of meter14 REF.OSCILLATOR:switchedonwhenthebuttonis depressed,the referenceoscillatorsuppliesa +10 dB signal to the direct amplifieron each channel,after the attenuator LINE/MIKE:line or microphoneinput selector,channel2 LINE/MIKE:line or microphoneinput selector,channell FI LTERS:6-positionfilter selectorswitch for channell: HPhighpass L1N.linear WE IGHTINGA, B, C, Dweightingcurves A, B, C and D METERFUNCTION:six-positionselectorswitch for meter 14 lEVEL.AVERAGEFAST: on the AVERAGEdecibel scale, average value of the soundlevel, fast characteristic,red needle for channelI, green needle for channel2 lEVEL.AVERAGESLOW;thesameasAVERAGEFAST,butslow characteristic LEVEL, PEAK: on thePEAK decibelscale, peak value of the soundlevel, channelsas above BATT.: on the BATTERIESscale, batteryor accumulatorcheck Red needle:batteryvoltage per cell (VOLTS/CELL) Green needle:voltage requiredby the motor,with the same reductionfactor as batteryvoltage PILOT8oCUE: Greenneedle:on thePILOT0 to100% scale, overall frequencydeviation causedby the pilotand CUE signals,100% on the scale correspondingto a deviationof 40% Red needle:on the PILOT +4 to -4% scale, frequencyshift, as determinedby the built-in OFMS frequencymeter, betweena signal recordedor played back on the thirdtrackand an internalreference Position M: Green needle:same as PILOT at this fre- quency, the sound level can be expressed in phones, the phones value being equal to the dB value read in relation to the 0.0002 /-Ibarreference. .The frequencyresponseof the humanear is not linear and depends very much on the sound level; a sound level meter must thereforeinclude weighting filters which modify the values measured in accor- dancewithcertaincriteria,so thattheycan be interpretedin relation to the subjective impression felt by the humanear.There are three standard weighting curves, A, BandC.Curve A is used for low and mediumsoundlevels, which are the sub- ject of mostanalyses;curvesBandC relate to higher levels.Curve D relates to contour-linesof perceivednoisiness,in particularwith noise pro- ducedby aviation:this weightingis used for the measurementof soundswhichcause annoyance in general.Curves A, B, G and D are shown after the specifications. Thesoundlevel measuredis shownon a dual galvanometer.withone needleper channel.Its measuringcircuitdeterminesthe average value of the signal onRMSandits peak value on PEAK,withdifferentdynamiccharacteristicsin relationto theintegrationtime.OnRMS FAST integrationtime is 200 ms: a signal at1kHz lasting 200 ms gives a reading1dB lower than that which would correspondto the steady signal.On RMSSLOW, integrationtime is 500 ms and a signal lasting 500 ms gives a reading 4 dB below that which would correspondto the steady signal. These two integrationtimes are in accordance with INSTRUCTION MANUAL IMeasurements theGEl standard179 forprecrsionsoundlevel meters.Naturally,any signal which is shorter than the integrationtime will be shownbelowits real value.Foranalysisof pulsesignalsor strong transientsa moreusefulreadingis obtainedon PEAK, i.e. peak value with an integrationtime of only5ms.This very fast reading cannotbe used becauseit causes visual fatigue:in order to over- come this disadvantagethe measuring circuit holds the signal for about one second, therebyincreasing the fall time of the needle. Recording and playback of the sound signals Inallcaseswheredirect.measurementis not sufficientfor studyingthe signals picked up by the microphone,these signals can be recorded on mag- netictapeand analyzedlater in thelaboratory. While the two tracks used for direct recording are in use, the thirdtrackCIOrecordF Msignals for synchronization,a commentary,or a measuring- signal fromD.C. up to 4 kHz.The threetracks thus store signals in fully-synchronizedform, which is an importantfactor for analysis. However, this storageis restrictedto some extent due to thelimitationsof presentmagnetictapes. Theselimitationsconcernthefollowingcharac- teristics in particular: the response curve Attenuationat the upper and lower extremesof the spectrum depends on the speed used.Very low frequencysignals, which are difficultto play back with a small reproducehead, shouldbe analyzed by frequencytransposition. distortion This increases very rapidly as soon as the maximum recordinglevel is exceeded,and tapesaturation occurs,generatingharmonicfrequencies(inpar ticular2nd and 3rd harmonics), which falsify the analysis of the signals. RadioFans.CN 收音机爱 好者资料库 I crosstalk The juxtapositionof the two channelsinside the recordinghead andthe playbackheadproduces crosstalk.This is the ratio, at a playback amplifier output.between the wanted signal and the unwan- tedsignalfromtheotherchannel.Crosstalk increases at high frequencies. I I The maximumpeak level, which correspondsto a tapefluxof32 mM/mm,is reachedwhenthe measuringinstrumentshows+10dBonthe RMSscale and+20dB on the PEAK scale. These two values are given in relation to the sound pressurereferencelevel0 dB=20 pPaor 0.0002J.1bar. OnRMStheintegrationtimeofthe measuringcircuitis long enoughnot to indicate shortpulses at their exact value and risk exceeding themaximumrecordinglevel, therebysaturating the tape.That is why, onRMS, the maxi- mum level is given at+10dB: the10dB lead avoids the signals with strong pulse content saturatingthe tape too Quickly. In all cases wherethenatureof a signal is not obviousit should be recorded with the measuring circuiton PEAK, which is the only way to make thepeak value of very short pulses visible and to avoid their exceeding the maximum recording level. Frequencytransposition Playbackspeedmay be differentfromrecording speed:this producesa frequencytranspositionof the signals recordedwithin the ratio of these two speeds.Since the response curve in thelow fre- quenciesis limited to25Hz on playback only, it is possible,if the tape transportspeed is ten times faster on playback than on recording, to play back frequencieswhichare ten times. lower.Thus, a 2.5Hz signal recordedat1.5ips will have a fre quencyof25Hz if it is playedbackat15ips (transposition1: 10), and can be analyzed easily by conventionalequipment.In the same way, the timeneededto analyzesignals whichvary very slowly is reducedin the same ratio by this process. Conversely.it is possible to analyze in more detail a signal whichvaries rapidlyby playingit back more slowlythanit was recorded.However,in bothcases, care must be taken that the transposi- tiondoes not alter the signals in any way, taking into accountthe limitationsof the frequencyres- ponse at the speeds used. I I I I I I I I I I Maximum frequency deviation tfo Frequencyresponse at-3 dB Signal-to-noise ratio for deviation of 20% 45% oto 4 kHz 44dB Peak-to-peakinputvoltage for deviation of 20% PILOT2_8 V CUE2.0 V IOPERATINGCONDITIONS Temperature with manganese batteries I with externalpower - 4to+160F -20to+71C -67 to +1600F -55 to+71C IThe recorderfunctionscorrectlyin any position. I J I ) 1 ht Wei21In2 curveA dB FfequencylEe Recommendation179NGRAIV.sJ RtI.tITolrnn Toler.nee Respomelimitl lImln +10 H,dBdBdB 2050.5 ,. !3 25 - . 7 :!:2.S 0 31,5-39.4 oJ., / . 40-34.6 oJ ., ./!-. SO-30.2 oJ., ./ -r-. 31.5 -17.1 1312 . 40-14.2 0312 ./ <, SO-u.s03t2 ./ 63- 9.3 0312 -10eo-7.4 12 :1:1.6 / 100- 5.e.,., 120 - 42 ., 11 / ISO - 3 -20 200 - 2 ., et V 260-1.311 316- D.e., 11 -30/ -0.5 1111 600 - 0.3 .,., 830 - 0.1 ., 11 800 0 tI11 , GOD 0at 11 1260 0 .,., -40 1e000 .,., 2000 - O.t 11 2500 - D.2 ., 11 3160 - 0. 11 4000- 0.7 1111 -506000-12 .11.5 11 8_ o1.8 .1.5 -2 ., 8000-a 1-t.fI -3 .11.5 10000 - 4.2 -4 i1.6 12500- 6.1 +3-611.6 18000- 8.4 +3 - il,6 Hz 20000-11.1 +3 - 8020050010003150800012500 2031,5 50100315800120050001000020000 _.-._-_.-r t ln I I I I J I I I J I I I J 2.4.Connectionof Brliel4133,4134,4149and4163 -1 ;4144,4145,4146and4161 -1,4;4135and 4136 -1/8;4 138 can 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,%:2618 The cartridgescan be fitteddirectlyontothe pre- amplifierswhen the diametersmatch;if they do not match,a mechanicaladaptercanbe used.The outputplugofthepreamplifierscrewsintothe OSJPadapterandtheplugofthepreamplifier adapter fits into microphoneconnector37:selector 10 should be on MI KE. Therecordershouldbe fittedwiththe QSJA-BK microphoneamplifierand the QSJC universal power supply.These circuitscan be installedas described intheprecedingparagraph, Signals and Voltages Chassis connectorexternalside or plugsoldering side +200Y +120V .J r - L_ ,-10G ,-r-GND +12,6V 2.5.Connectionof Sennheiser MKH 110 Measuring Microphone The MKH 110 microphoneconsists of a capacitor cartridgeand an electroniccircuitwitha low impe- dance output;microphonesensitivityis 2 mVIMbar. It shouldbe connectedtomicrophoneconnector 37by the QCJ-MKHcable; selector10 shouldbe on MIKE_ The recordershouldbe fittedwiththe QSJA-MKH microphoneamplifier,whichalso supplies the vol- tage for the microphone. Installationof aSJA-MKHAmplifier Lockthe lid of the recorder,turn screws 50 several times and open the case to its full extent.Unscrew the connectorbetween the microphoneinputwiring and the case interconnectionboard.Plug in and fix thisconnectortothemicrophoneamplifierand secure the latter to the case interconnectionboard. Unscrewthe level adapterboard.Place the shield in positionand fixit undertile groundcomband undera nutscrewedontoone of the twohinge fixingscrews (this screw should be longer - M3x8). Reinstallthe level adapter board. Signals and Voltages Chassis connectorexternalside or plugsoldering side -.,.-GNO -8Y- SIGNAL -10G- , , I , I I I I I I 3.DIRECTMEASUREMENTOF SIGNALS 3.1.Position of the Controls Set switch1 on DIRECT: switch 2, which cannot be locked in position,remains on DIRECT.Turn main selectorswitch 4 to TEST: the circuits are then switchedon and will stabilize after about 10 seconds. 3.2.Selection of Measuring Circuit Set the METER FUNCTION switch on one of the LEVEL positions: - RMS FAST: average valu of the sig nal on the RMSscale of meter14, integrationtime 200 ms. -RMSSLOW: averagevalue of the signal on thesame scale, butintegration time 500 ms. -PEAK:peakvalue of thesignal, onthe PEAK scale of meter14, integrationtime 5 ms, witha memorycircuitholding the signal for about1second. The measuringcircuitof the recordershould be selectedin accordancewiththe criteriagiven in Section3. 3.3.Adjustmentof the Monitoring Circuit The signals can be monitoredon the headphones with switch4in any position and with the built-in loudspeakeronPLAYBACKwithLoudspeaker (see 6.). Themonoheadphones,impedance50 to 600n. plug into jack 17.The requiredchannelcan be selected with switch18and the loudness regulated by potentiometer19,which can be adjusted with a screwdriver. 3.4.Choice of Sensitivity 3.4.1.Highlevel Signals on the Line Input Set selector10 on LINE, turnmain attenuator7 fully to the left, or on GND, set vernier attenuator 7Aon0dB (CAL.), Switchon the signal source connectedto the line input.While watching meter 14, turn main attenua- tor 7 totheright untilthered needle makes a visible movement.Calculate the value measured as described in paragraph 3.6.1. 3.4.2.High-level Signals on the MicrophoneInput Same procedureas in the preceding paragraph, but with selector10on MIKE. 3.4.3.Lowlevel Signals on the MicrophoneInput QSJA-BK AMPLIFIER With selector10on MIKE, set vernier attenuator 7Aon0dB Turn the cartridge type selector 40 to the position which correspondsto the diameter of the cartridge used.On1f.t thepositionsof gain selector39 become +40. +60 and +90dB, values inscribed in a circle. Turn attenuator7to +20 dB and watchmeter14. If theneedlemoves noticeablybeyond+20 dB PEAK or +10 dBRMS,turnswitch39to +80 dB.If the needle is clearly below 0 dB, turn switch 39 to +40 dB. Calculate the value measured and take into accountthe restrictionsdescribedin paragraph3.6.3. QSJA-MKH AMPLIFIER This amplifier has no gain selector or cartridge type selector.The sensitivity can be determinedby main attenuator7only. AMPLIFIER FOR GENERAL RADIO MICROPHONE The amplifier for use with the GENERALRADIO microphoneis theQSJA-BK;please refer to the above instructionsfor using this amplifier. 3.5. Choice of Filter When filter selectorswitch11 is on LlN, thefre- quencyresponseof thedirectchainislinear at :to.3 dB from 2.5 Hz to 35 kHz. Selector switch11 shouldbe set on one of the followingpositions according to the kind of measurementsbeing taken: HP: high-passfilter,attenuation3dBat 20 Hz, 12 dB per octave WEIGHTINGA, B, C, D: weightingof the frequencyresponseasdeterminedby internationalstandards,the exact value of which is given at the end of the section entitled Specifications. The HP position should be used systematicallywhen the measurementof signals is not extendedto very low frequencies:in fact, since these are inaudible, they are likely to falsify results and, in some cases, saturatethe amplifiers.Furthermore,this position eliminatesvery low frequencynoise from the car- tridge itself. The weighting positionsA, B, C and D are used, in the case of noise measurement,to obtain a value correspondingto the subjective impression felt by the human ear (see Section 1). I-I i- II I-J J I , The arrowheadoppositethe +40 dB positionon attenuator7is to remindtheuser thatcertain restrictionsmustbe observedin orderto avoid saturationof the input circuits, when measurements are takenby microphone,preamplifierand ampli- fier. The performanceof the microphonecartridges and input amplifiercircuitsis restrictedby the occur- rence of saturationphenomenawhich are produced when the sound level