ADC-SoundShaperThree-ss-sm维修电路原理图.pdf

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1、ServiceManualSTEE() FE()UEN(YE()UALllEflAudio Dynamics CorporationRadioFans.CN 收音机爱 好者资料库-CONTENTS-PAGEELECTRICALPERFORMANCESPECIFICATIONS3CI RCUITDESCRiPTION,4-9SWITCHFUNCTIONS0-12DISASSEMBLYINSTRUCTIONS2BLOCKDIAGRAM.ADJUSTMENTPROCEDURES-CALIBRATORSCHEMATIC. . . . .-TROUBLESHOOTING- SYMPTOM CAUSE/R

2、EMEDYi7- :AMP P. C. B. (TOP&BOTTOMVI EWS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .POWER SUPPLY&METERP. C. B. (TOP&BOTTOMVI EWS)SWITCH (L)P.c.B. (TOP&BOTTOMVIEWS)21SWITCH (R) P.c.B. (ROP&BOTTOMVIEWS)22SLIDEVOLUME (L)P.c.B. (TOP&BOTTOMVIEWS)23SLIDEVOLUME (R) P. C. B. (TOP&BO

3、TTOM VIEWS)24ELECTRICALPARTSLIST25-34EXPLODEDVIEWPARTSLIST35-36MISCELLANEOUSPARTSLIST37SCHEMATICDIAGRAM38-39EXPLODEDVIEW40-41-2-RadioFans.CN 收音机爱 好者资料库-3 -ELECTRICALPERFORMANCESPECIFICATIONS(Unit)(Nominal)(Limit)Frequency responseat flat position,Input level=0.775 V(Hz)5-100KU dB5-100K?:5dBControl F

4、requency accuracyat 26, 32, 39 Hz(%)510at 47, 56, 68 Hz(%)510at 84,100,120Hz(%)510at 150,180,215Hz(%)510at 260,320,390Hz(%)510at 470, 560, 680 Hz(%)510at 840, 1 K, 1.2 KHz(%)510at 1.5 K, 1.8 K, 2.15 KHz(%)2.5 5at 2.6 K, 3.2 K, 3.9 KHz(%)2.5 5at 4.7 K, 5.6 K, 6.8 KHz(%)2.5 5at 8.4 K, 10 K, 12 KHz(%)2

5、.5 5at 15 K, 18 K, 21.5 KHz(%)2.5 5(Output level=0.775 V)Control range at 0.775 V Input(dB)+13.5+125-13.5-12.5Harmonic Distortionat 1 V Outputfrom 20 Hz to 20 KHz(%)0.0180.04Hum and Noise ratio at 1 V Output(dB)9085(Input shorted) (IHFA)Dynamic Range into 10 Kn load(V/rms)109(All Controls should be

6、Flat)Input Impedance(Kn)75Output Impedance at 1 KHz(n)10IntermodulationDistortionat 1 V Output,70/70 KHz at 4/1 ratio(%)0.020.05Meter tolerance (Frequency at 1 KHz)at+12dBpoint(dB)0.51.0atOdBpoint(dB)0.51.0at-12dBpoint(dB)0.51.0at other points(dB)1.01.5NOTE: When each control range is measured, all

7、other controls should be at center (0 dB).RadioFans.CN 收音机爱 好者资料库SOUNDSHAPERTHREECIRCUITDESCRIPTIONMAINPOWER SUPPLY (Refer to Figure A)Power TransformerT 1001 providesthree tapped secondarywindings.One delivers+26.4V/- 26.0V DC at +104/-137rnA(noiall frocapacitorcircuitconsistingof a bridge rectifie

8、rD701 and C73,C74.Theseconddelivers-25.2VDCat -1.1rnA(nominal)froacircuitconsistingof rectifierD709 and C715. This voltage supplies- eTR201.The thirddelivers 60 VDC at 87.5 mA (nominal)fromfull-waverectifiing of rectifiersD702,D703 and C704.Thevoltagewhichis rectifiedby D701providesbothbases of TR70

9、3cTandR717.TR703/TR705andTR704/TR706consistof voltage-regulatorcircuitsorvoltages.Theseregulatorcircuitsprovideapprox.+15.4V/-15VDC toLEDMeterana5Controlcircuitwhichare constantand independentof the load current.The referencevoltage of this circuitis obtainedfromZener DiodeD708. The base voltage of

10、Tis suppliedfromthe voltage dividerR708 and R709.TR703turn-onis determinedby comparingtheoutputvoltagetothereferencevoltageandiscontrolledby changes in collectorcurrentof TR705.Voltage,whichis rectifiedfromD702 and D703,dividernetworkR702 and R705 providesapprox.50 VDC.Thisis filteredfurtherby C703,

11、R704and fed to the base of dividertransistorTR701whichis connectedto TR702in a Darlingtonemitter-followerconfiguration.The reference voltageof this circuitis obtainedfromZener Diodes D704 and D705(Approx.44 VDC).The emitterof TR702,decoupledby C701, providesapprox.41.5 VDC to the Equalizerand Meterc

12、ircuits.The collectorsTR701and TR702are returnedto 57.4 VDC throughR701 whichlimitsthetransistorcollectorcircuits.TheDarlingtonconnectionof TR701and TR702providesa low outputimpedance.The base ofTR701presentsnegligibleloadingonthevoltagedividernetwork,hence theripplevoltageatTR702emitteris small.Exc

13、eptfor the small base currentintoTR701,the fullload currentflowsthroughR701.a full-wavebridge rectifier-CIe rocifier- cspactitorcireui,e base ofcoFigure A-4 -RadioFans.CN 收音机爱 好者资料库LED METER COMPARATORCIRCUITDESCRIPTIONPower Supply and bias configuration(Refer to LED METERcircuits)Thepowersupplyfort

14、he LEDMeter Comparatorcircuitconsists of full-waverectifiers,whichprovide plus (+) and minus (-)+15.4/-15VDC to each of IC802 throughIC814.LED indicationlevel is provided from the Zener diode D71 0 (-5.6VDC).The+15.4/-15VDCsourceisappliedtoLEDcomparatorICsIC802throughIC814.The-5.6VDCsource providesa

15、 stable voltage to VR801(L)and VR802(R) forLEDMeterindicatorlevel.Signal to the (-)inputcauses a change in outputthat is invertedin phase relative to the input.Signal to the (+) input causes a change in outputthat is in phase with the input.Withno signal toRin, the (+) inputsees 0 Volts throughRB, c

16、ausing the outputto be positive-going. (-)input voltage is equal to (+) input voltage(=0 V) - known as Imaginal Short.When the outputreaches 0 V, the (-)inputalso sees0 V-throughresistor RF and furtheroutputchange is inhibited.The output,(+) input and (-)input are now all 0 V.The (-)input remains at

17、 0 V regardless of the signal into Rin.Example:Aninputmore positivethan0 V toRin causes the outputto be negative-going.Theoutputcontinuesto dropuntilthe feedback throughRF is lowered by an amountsuf-ficientto equalize the imbalancebetween the (+) and (-)inputscauses by the inputsignal. Because of th

18、e amplifiershigh gain and speed, the imbalance between the (+) and(-)inputs is always small.Since the voltage at the (-)inputis always at 0 Volts,the (-)inputis effectivelyat AC ground.Therefore,the entire input signal appears across Rin and the entire outputsignal appears across RF Since the (-)inp

19、ut voltage is always 0 V the currentinto the amplifiers(-) input is constant. Sincethis currentis suppliedby Rin and RF any change in currentdue to inputsignal throughRin isoffset by an opposite and equal change of current throughRF.For AC signal currents,if we ignore the negative values indicatings

20、ignal inversion,the gain of theamplifiercan be calculated as follows.I (Rin)=I (RF)Since1=g_E (Rin)=E (RF)_B_E=E (RF)GAINRRinRFRinE (Rin)NOTE: RC4709of this circuitoperates fromsplit power supplies.plus (+) supplyat Pin No. 14and minus (-)supply at Pin No.7.OPERATIONALAMPLIFIERFEEDBACK CIRCUIT (Refe

21、r to Figure B)AMP OUTPUTBASIC OP. AMP.FEEDBACK CIRCUITFigure B- 5 -RadioFans.CN 收音机爱 好者资料库PRECISIONHALF-WAVERECTIFIER ANDAMPLIFIERCIRCUIT (Refer to Figure C)The basic fau It withdiode rectifiercircu its is that the diodes do not conduct until a specific voltageis reached. The above circuiteliminates

22、 this problem and also amplifies the output.Referringto the basic circuit,note that:(1) Withno inputsignal 0801is conductingslightlytoestablish 0 V DC atA (-)input and 0 V DC atAout; (2) When 0801is barely conductinga smallamountof feedback exists. Therefore,the gain of the amplifieris very high. Le

23、ssthan one millivoltwillcause the outputto change by a volt or more. Operationis as follows:Anegative input causesa positive-goingchange in the amplifieroutput.Since the gain is high until0801 conducts fully,theamplifieroutputjumps to 0.2 Voltslong before the inputreaches a millivolt(in a very short

24、 time).Atthispoint0801is fullyconducting,has a low impedance compared to RF(n), and exhibitsa0.2 V dropacross it. The rectifieroutputis now -85mV DC. Since the feedback loop (RF)hasbeen completedby 0801any furtherdecrease in input voltage is amplifiedby the ratio of RR.(n)which is approximatelyequal

25、 to 5 for this circuit.InA positiveinputcauses the outputto decrease in a manner similarto just described except thefeedbackis through0803and RF (p). The amplifieroutputis blockedfromappearing at therectifieroutputby 0801(0801is reverse biased withrespect to the followingstages which arereturned to

26、the 0 V DC line).In this manner, appearing at 0801 cathode are negative half-wave pulses whose amplitudeis directlyproportionalto the input signal level.The followingrefers to the complete schematic:The negative pulses at 0801 cathode are filteredinto an average DC voltage by R809 and C807, andthis

27、voltage servesas input to the LED meter comparator.R803 and 0803serve to maintainpositive feedback aroundRC4709 during the positive half-waveexcursions of the input signal. As the amplifiersoutputis positive during this time, 0803 is forwardbiased (0201is off)and the feedback path now consists of R8

28、03 and 0803. The amplifieris thuskept out of saturationand free from oscillationsthroughoutthe full input cycle.Bias circuituses splitpower supplywhichprovides +15.4 V DC at Pin No. 14 and -15V DC atPin NO.7on IC801.r-_R_F-/V(Ny-e_g_.)- - - - .- - 0RECT IFIE ROUTPUT0801RF(Pos.)0803(AMP OUTPUT)BASIC

29、OP. AMP.RECTIFIER-AMPLIFIERCIRCUITFigure CCOMPARATORCIRCUITFOR LED LEVEL METER DESCRIPTIONComparatorcircuitoperationComparatorcircuitconsts of 13 ICs MJM-4588DM.Comparatoroperates by comparingthe (-)input level to (+) input level, in which outputvoltage ischanged from minus to plus Voltage. Thus DC

30、currents flows to each LED.- 6 -RadioFans.CN 收音机爱 好者资料库Withno signal, (-)inputlevel No.2(L) or No.6(R)1is kept to 0 V DC.(+)inputlevelPinNO.3(L)or PinNo.5(R)lofIC814is keptto minusDC voltage(about-45mV)by half-waverectifiersthroughVR801(L)VR802(R)land VR805(L)VR806mnThus,theoutputvoltageofIC814PinNo

31、.1(L)or No.7(R)1is keptwithminusDC voltage.When minusDC voltageis appliedto (-)input,and causes the (-)inputvoltageto be greater (orequal) to the (+) inputvoltage,the outputappears as plus DC voltage.(V3:s.V2)ThusLEDD925(L)and D926(R) are lit at -12dB points.ButD901throughD924are notlitbecause the i

32、nputvoltageis too low.Each LEDconductswitha (-)inputlevel whichis determinedby VR801(L), VR802(R) (IC802),R813 (L),R814 (R) (IC803),R817 (L).R818 (R) (IC804),R821 (L),R822(R)(IC805),R825(L),R826(R)(IC806),R829 (L),R830 (R) (IC807),R833 (L),R834 (R) (IC808),VR803(L), VR804(R)(IC809),R839(L),R840(R)(I

33、C810),R843(L),R844(R)(IC811),R847(L),R848(R)(IC812),R851 (L),R852 (R) (IC813),R855 (L),R856(R) (IC814).Withan increase in minusDC voltage,providedto the (-)input,each LEDis lit in sequence fromD923,D924 to D901,D902.CIRCUITDESCRIPTIONFREQUENCY EQUALIZATIONTheinputsignal is fed intoTR101base. TR101,a

34、n emitterfollower,providesthe highinputim-pedancerequiredby thesignalsource.Thelow outputimpedanceof TR101is requiredto drivea voltagedividerformedby R111 and the sectionsof the frequencycontrolpotsbetweenthe cutend ofeach controlandits wiper.Thewiperof each controleffectivelyqroundsonlythose freequ

35、enciesresonatedby the series traps(coil,capacitorand resistorfromwiperto common).Thus,the voltagedivisionwhichoccurs can be differentfor each frequencyand depends on the frequencycontrolsettings.TR103,TR105and TR107are connectedso thatthe voltageat TR105base alwaysfollowsthevoltageat T R103 base. Fo

36、r example:An increase in voltageat TR 103 base causes the conductionofTR 103 and TR 107 to increase, and feedbackbase driveof TR 105 to increase, untilthe voltageatTR105base is equaltothatat TR103base. Conductioncannotincrease beyondthispointsincethe emittervoltagesuppliedby TR105thentends to make T

37、R103conductless. Conversely,a de-crease in voltageat T R 103 base causes a correspondingchange at T R105 base.Theoutputvoltageis takenfromTR107collectorand is also fed back to TR105base throughthevoltagedividerformedbyR115 and the sectionsof the frequencycontrolpots betweenthe boostend of each contr

38、oland its wiper.Foreach frequency,movingthecontrolpotoffcentertowardsboostcauses an increasein theamplitudeof the signal presentedto TR103base and a decrease in the negative feedbackto TR105base. The gain is thusincreased.Since the signal amplitudesat the bases of T R103 and T R105 arealwaysequal,th

39、e outputsignal dividedby the feedbackattenuation(R 115 and boostsections)isapproximatelyequaltotheinputsignalamplitudedividedby theinputattenuation(R 111 andCUTsections).By followinga similarline of thought,it willbe seen that when the controlsarecenteredthe gain is unity;and when the controlsare to

40、wardscut, the gain is less than one.Theresistorsin series withthe series resonantcircu its are used to increase the bandwidthor lowertheQ,ofeach circuitso thattheeffectof controlsof adjacentfrequenciesoverlap,thuspro-vidinga smoothoverallresponse.Theresistorsare ofdifferentvaluesso thatthetotalserie

41、sresistanceof each circuit(coiland resistor)is approximatelythe same. The ratioof the totalseriesresistance of the resonantcircuitto the base resistorof TR 103 and TR 105 determinesthe maximumboost or cut obtainable.-7 -RadioFans.CN 收音机爱 好者资料库SIGNAL GAIN CONTROL CIRCUITSignal Gain Controlcircuitcons

42、ists of T R109, 111, 113 and 115 (L ch) and TR 110, 112, 114 and116(Rch).This circuitconfigurationis identicalto theFrequencyEqualizationcircuit.For operating,seeFrequencyEqualizationdescriptionsection.The input signal is fed into TR 109 base.TR111,TR113and TRl15are connectedso thatthe voltage at TR

43、105base always followsthevoltage at T R111 base.Totalgain can vary fromnegative feedback value which consists of R135, VR101and R143 (L ch)R136,VR102and R144 (R ch).When basevoltage of T R111 is equal to base voltage of TR 113, the gain is unity.COMPARATORCIRCUITFOR SIGNALGAIN CONTROLINDICATOR(LEDCo

44、mparatorcircuitconsists of three ICs NJM 4558DM.ComparatoroperatesbycomparingtheINPUTsignaltooutputofTR 115. These signals aresuppliedtoPin 6 and Pin 2 ofIC201(Lch)or IC202(Rch) . Bothinputlevels are doubledtooutputterminals(Pin 6 to Pin 7 and Pin 2 to Pin 1).Outputof Pin 7 is positive, half-wave re

45、ctifiedby D203 and filteredinto an average plus DC voltageby C207 and R221, and this voltage is applied to(+)input at pin 3 of IC203.In the same manner, the outputof pin 1 is positive,half-wave rectifiedby D201 and filteredintoan average plus DC voltage by C205 and R233, and this voltage is applied

46、to the (-)input at pin 2of IC203.Thus, the differencelevel between Pin 2 to Pin 3 appears at Pin 1 of IC203. This voltage at Pin 1serves as input to the Signal Gain ControlindicatorLED.For example,when theinputlevel at Pin 2 is small comparedwithPin 3, the outputat Pin 1appears as positive voltage (

47、approx.13.6 V DC).Thus, LED D1003 willlight but D1002 will not.When the inputlevel at Pin 2 is greater comparedwithPin 3, the outputat Pin 1 appears as anegative voltage (approx. -12.3V DC).Thus, LED D1002 willlight but D1003 will not.When the inputlevel at Pin 2 is equal to Pin 3 input level, the o

48、utputwill appear as zero, and thusboth LEDs D1002 and D1003 willlight. In this case, the gain is unity.(Figure D)OSCILLOSCOPESS-3,- - -f-oc:=oMH0illiMMIIlII1o0o-+-:BBBBBBBBBBBB BBBB88BBB888c:;-fPoINPUTOUTPUTAUDIOOSC.FREQUENCYAC V.TV.M.(20. 20KHz)EQUALIZERI- I-:;):;)Q.Q.Z020902100100201003Figure D-8-

49、RadioFans.CN 收音机爱 好者资料库IIoff.POPPINGNOISEPROTECTIVECIRCUITThis circuit eliminates the popping noise in the speakers when the power switch isturned onorThis circuit consists of TR201, TR202, TR203 and a Reed Relay.When power is switched on,-0.5VDC is provided to the baseof TR201 through R238. TR201wi

50、ll turn off. Afterabout 6 seconds, TR202, TR203 will turn on. Thus the Reed Relay will restoreconnections to the OUTPUT Terminals.When the power switch is off,1.7 VDC is provided to the baseof TR201 through R237. TR201willturnon, TR202and TR203willturnoff. And thus the Reed Relay will disconnect the