Realistic-31_2078-rec-sm 维修电路原理图.pdf

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1、-aLtstCSerulceSTA-168AM/FM STEREO REGEIVERCatalog Number: 31 -20780B RADIo sHACK fln DMSIoN 0F TANDv coRponAloNCUSTOM MANUFACTURED FRadioFans.CN 收音机爱 好者资料库1)2l3)45)6)7l8)e)10)11)12113)14115)16)ELECTRICAL PE RFORMANCED ISASSEMB LY I NSTRUCTIONSDIAL STRINGING DIAGRAMBLOCK DIAGRAMALIGNMENT INSTRUCTIONS

2、 .,.,7_LEVEL DIAGRAMSPECIFICATIONS,3-4TROUBLESHOOTINGAM/FM TUNER, IF & MPX P.C.B. (TOP & BOTTOM VIEWS)PRE AMP & TONE CONTROL P.C.B. (TOP & BOTTOM VIEWS)11-1213145569101516MAIN AMP P.C.B.JACK P.C. B.POWER SUPPLY P.C.B. (TOPIC & TRANSISTOR LEAD IDELECTRICAL PARTS LIST(TOP & BOTTOM VIEWS)(TOP & BOTTOM

3、VIEWS)15& BOTTOM VIEWS)ENT|F|CATION . 1617 -2223-2424-2526-27MECHANICAL PARTS LISTIC INTERNAL DIAGRAM17) SCHEMATIC DIAGRAM18) EXPLODEDVTEW .28-29-2-RadioFans.CN 收音机爱 好者资料库1 ELECTRICAL PERFORMANCE SPECIFICATIONSAM BANDFrequency CoverageIFAntenna Sensitivity for S/N 20 dBat 600 kHzat 1000 kHzat 1400 k

4、HzTerminal Sensitivity (S/N 20dB)ACA at S/N 6 dB Sensitivity at 1000 kHzAGC Distortion at 1000 kHz1000 mV/m, 80% modulationAGC Figure of MeritI F Rejection at 600 kHzlmage Rejection at 1400 kHzDistortion at 5 mV/m 30 % modulation 400 HzTape Out Level 5 mV/m 30 % modulation 400 HzFidelity 5 mV/m lnpu

5、t (1 kHz = 0 dB) -6 dB downWhistle Modulation of 2nd and 3rd Harmonicat 1 and 5 mV/m lnputCalibration Accuracy at 600 kHzat 1400 kHzS/N Ratio at 5 mV/m lnput, 1000kHzFM BANDFrequency Coverage (For UL AND C.S.A.)Frequency Coverage (For European and Australian)IFIHF Sensitivity at 90, 98 and 106 MHzS/

6、N Ratio at 1 mV lnputFM Limiting - 3dBI F Rejection at 90 MHzlmage Rejection at 106 MHzCapture RatioACA t 400 kHz at 100sVAudio THD 400 Hz, 75kHz Dev.Calibration Accuracy at 90 MHzat 106 MHzAFC Holding Range with 1 mV SignalTHD at Maximum Signal Handling Capacityof 200 mV lnputTape Out Level 75 kHz

7、Dev. 400 Hz 1 mVNOTE: All sets must meet the requirements of the FCC.75 psec. de-emphasis for UL and C.S.A. modelsand Australian models).* European models must not be able to tune belowUNITkHzkHzpV lmpV lmuV lmrrVdBo/okHzkHzdBMHzMHzMHzpVUNIT NOMINAL LIMIT41t3dBFrequency response must meet the(50 pse

8、c. de-emphasis for European87.5 MHz.NOMINAL LIMIT515 - 1650 520 -162545550050050022103828353.52002AO2002001530ot/odBdBdBo/omVHz44536451.525050 - 2500543dBpVdBdBdBdBo/okHzkHzkHz10t25t503786.5 - 108.5 88 - 108*87.5 - 108.5 87.5 - 10910.72.8 5.0(14.1 dBf) (19.2 dBf)58 503670 6045 352.5 640 250.6 1.5t 5

9、00r b00t 300 t 300 t 150o/o 1.5V1-3-FM MPX SECTIONStereo lndicator ON LevelSeparation at 1 mVat 100 Hzat l kHzat 10 kHzStereo Distortion 1 mV 1 kHz38 kHz RejectionS C A RejectionAUDIO SECTIONlnput lmpedance PHONO Mag.AUXOutput Power at THD of 0.9 %, 8 ohmBoth Channels Driven at 1 kHzPower Output, 8

10、ohms, Both Channels Driven,THD 0.9 o/o, 30 Hz - 2O kHzSensitivity for Rated PowerPHONO Mag.AUXFrequency Response at AUX (1W t 2 dB)BASS Action at 100 HzTREBLE Action at 10 kHzHum and Noise at Min. VOLUMEHum and Noise at Max. VOLUME,Tone Max. (AUX mode)Signal to Noise Ratioat PHONO Mag. 5 mV lnput (l

11、nput Short)at AUX 200 mV lnputCross Talk at 1 kHz AUXBass Compensation at 100 Hz, -30 dB VOLUMETreble Compensation at 10 kHz, -30 dB VOLUMETAPE OUT Level PHONO Mag.at 5 mV lnputAUX at 200 mV lnputPHONO Mag. Eq. Response at 100 Hzat 10 kHzPHONO Mas. Overload (THD = 0.9 %)UNITpVdBdBdBo/odBdBUNITK ohmK

12、 ohmWWmVmVHzdBdBmVmVNOMINAL10NOMINAL504507.Ob2.515040 - 22kt 10t 10120LIMIT202530222.040403338300.85555606060+9+4dBdBdBdBdBLIMIT5.553.520050-18kt 10 r 3t 10t 3370505045+9 t 3+4t3250 200250 200+13 +13t2-13 -13t282 70mVmVdBdBmVNOTE: The supply voltage is 120 volt AC,60 Hz (for UL and C.S.A. models) fr

13、om a regulatedpower supply. lUse 2201240 volt AC, 50 Hz for European and 240 volt AC, 50 Hz forAustralian models.)The power source must be isolated f rom other equipment connected to antenna or output.The room temperature is 25 degrees C.Nominal Specs represent the design specs; all units should be

14、able to approximate these- some will exceed and some may drop slightly below these specs. Limit Specs representthe absolute worst condition which still might be considered acceptable; in nocase shoulda unit perform to less than within any Limit Specs.-4-2I DISASSEM BLY I NSTR UCTIONS1) To remove cha

15、ssis from wood-en cabinet.Turn the cabinet upside downand remove the four Pan headscrews from the bottom cabi-net.*-44qrCaia*.W,i2) Removal of front panel (Alu-minium panel).a. Remove the chassis fromwooden cabinet as describ-ed in 1).b. Pull out the main chassis.c. Remove the two Pan headscrews fro

16、m the top and thethree Pan head screws fromthe bottom of the frontpanel.d. Remove knobs and pull offpanel.3) To remove rear panel fromchassis.Remove the three Pan headscrews from the rear panel.3 DIAL STRINGING DIAGRAMP(r) IPIeStart with Capacitor set withPlates Fully Unmeshed.o Pointer position: HI

17、GH END. Start : Springo Finish: Hook+RNS)t2t/.&)3). I2 TUm6.-5-4I BLOCK DIAGRAMff=YUflhtrSAofooIIIIIIIIIIIIIIIIIIIIIIJaiE:Zoro=-,lulzlzlg86fr8leUi=_Edd6E-u9dliFg=ooooo=EL=u9EGIIOF=a-6-5 ALIGNMENT INSTRUCTIONSEOUIPMENT REOUIRED1. AM Signal Generator2. AC Voltmeter3.OscilloscopeAM IF & RF ALIGNMENTNOT

18、E:o Signal Generator output should be no higherthan necessary to obtain an output reading.r Maintain line voltage at 12O volts. (UL, C.S.A.)(Use 22Q1240V AC For European & AustralianModels.)o Set SELECTOR Switch to AM.o See P.C.B. illustrates for alignment points/ad-justments.TUNER COIL & TRIMMER LO

19、CATIONSAM INTERNAL BAR ANTENNAFC 1O1) OC 104) OC rO2) fiC 1o5)FM ANT AM ANT FM RF AM OSC.TRIMTTER TRIMMER TBIMMER TRIMMERAM ALIGNMENT SET-UPAM SIGNAL GENERATOR ii._- 2 (6ocm)FM RF & IF ALIGNMENTEOUIPMENT REOUIRED1. FM Signal Generator . . Output2. Sweep Generator3. AC VoltmeterNOTE:o Signal Generato

20、r output should be no higherthan necessary to obtain an output reading.o Set SELECTOR Switch to FM.Figure 3Level: 1 mV4. Oscillator5. Distortion Metero Maintain Line voltage at12O volts. (UL, C.S.A.)(22O/24OV AC For European & AustralianModels.)o Refer to P.C.B. illustrations for test points/ad-just

21、ments.lo.VO LTMETE RSTEPSIGNAL GENERA.TOR COUPLINGSIGNAL GENERA-TOR FREOUENCYDIAL SET.TINGINDICATORADJUSTMENTREMARKS1Connect standardloop ANTENNA toSignal Generator andradiate s ignal intothe AM Ferrite an-tenna. See Fig.3.455 kHz(400 Hz, 30% MOD)Point ofnon-i nterfer-ence (near600 kHz)AC Voltmetert

22、o TAPE OUTJackT106T1 07T108T109Adtust for maxi-mum reading2Same as above600 kHz (400 Hz,30 % MOD)600 kHzSame as aboveT105 (OSCCoil)L6O2 (AM ANTCoil)Adjust for maxi-mum reading3Same as above1400 kHz (400 Hz,30% MOD)1400 kHzSame as aboveTC105(OSC Trimmer)TCl04(ANT Trimmer)Adjust for maxi-mum reading4R

23、epeat Steps 2 and 3 until no further change is noticed.5Same as Step 1.1000 kHz (400 Hz,30% MOD) Outputlevel to 100 mV/mPoint ofnon-i nterfer-ence and nosignalAM StrengthMeter onReceiverSelect value ofRr60Select value soMeter Pointer onReceiver readsbetween SOYoand 90 % on theMeter-,/TAPE OUT (L or

24、R)-7 -STEPGENERATOR COU.PLINGGENERATOR FRE.OUENCYRADIO DIALSETTINGINDICATORADJUSTMENTREMARKS1Sweep Generator toTP3 on FM Frontend boad10.7 MHz(1400 kHz Sweep)Any dial set-ting whereno notse orintdrferenceexistsScope to TP7at R151(MPX input)AM/FM/MPXBoardT101,102,103,104 (Primary)FM IFTAdjust for max

25、imumamplitude and prop-er linearity between1150 kHz markersRefer to Fig. 5.2Sweep Generator toTP3 thru FM Dum-my antena(300 ohm)10.7 MHz(1400 kHz Sweep)Any dial set-ting whereno noise ori nterferenceexistsScope to TP7at R151(MPX input)AM/FM/MPXBoardT101,102FM IFTAdjust for maximumam,plitude and prop

26、-er linearity between1150 kHz markers.Refer to Fig. 5.3Same as above10.7 MHz(1400 kHz Sweep)Any dial set-ting whereno noise ori nterferenceexistsScope to TP7at R151(MPX input)AM/FM/MPXBoardT104FM IFT(Primary andSecondary)Adjust for symmetri-cal S curve asshown in Fig. 44Signal Generator toF M Antenn

27、a Ter-minal thru FM Dum-my antenna(300 ohm)98 MHz(400 Hz, 100%MOD)Tune forMaximumreading onmeterDistortionMeter to TAPEOUT JackT104FM Discrim.(Secondary)Adjust for minimumdistortion5Same as above*86.s MHzSee Note in Step 7.Tuning gangfully closedAC Voltmeterand Scope toTAPE OUTJackLl 05(FM OSC)Adjus

28、t for maximumreading on meterbSame as above108.5 MHzTuning gangfully openedAC Voltmeterand Scope toTAPE OUTJackTCl03 (FMOSC Trimmer)Adjust for maximumreading on meter7Repeat Steps 5 and 6 until Tuning Range Covers exactly from 86.5 MHz to 108.5 MHz.(*European & Australian models must not be able to

29、tune below 87.5 MHz.)8Signal Generator toFM Dummy antenna(300 ohm)90 MHz90 MHzTune toSignalAC Voltmeterand Scope toTAPE OUTJackL1 01(FM ANT Coil)1103 (FM RFCoil; stretch orsqueeze)Adjust for maximumreading on meteroSame as above106 MHz106 MHzTune toSignalAC Voltmeterand Scope toTAPE OUTJackTC1O1 (FM

30、ANT Trimmer)TCl02 (FM RFTrimmer)Adjust for maximumreading on meterl0Repeat Steps 8 and 9 until no further improvement is noticed.11Same as Step (8)ANT. input: 1 mV98 MHz98 MHzTune toSignal10T1Adjust for maximumreading on meter12Same as Step (8)ANT. input: 100mV98 MHz98 MHzTune toSignalVR101Adjust so

31、 the MeterPointer on Receiveris full scale.FM ALIGNMENT SET-UP3OOO DUMMY FM ANT(l_ u, tortPATTE RNTAPE OUT(L or R)Figure 5FM SIGNAL GENEBATORSCOPE PATTEBNFigure 4Sweep Gen-8-AC V.T-V.M-DISTORTION METERFM STEREO ALIGNMENTEOUIPMENT REOUIRED1. Stereo Modulator. Connect Stereo Modulator to EXT, Mod. ter

32、minal 3. Audio GeneratorFM signal generator. 4. AC VoltmeterModulation Level of 19kHz Pilot Signal . . 8-1o/o b. Oscilloscope2. FMSignal Generator.OutputLevel .1mV 6. Distortion MeterFrequency . Approximately g8 MHz. 7. Frequency CounterDeviation .75kz l0yo modulation ofcomposite signal.NOTE:o See P

33、.C.B. illustration for alignment/test points. Set SELECTOR switch to FM and MODE switch to STEREO.MULTIPLEX & SEPARATION ALIGNMENTSTEPSIGNAL GENERA.TOR COUPLINGSTEREO MODULA.TIONIND!CATORADJUSTMENTREMARKS1Connect to FM An-tenna Terminal thruFM Dummy antenna(300 ohm)Mono.1 kHz(1000 Hz, No ttlod)lnput

34、 1 mVCounter connectedto TP14 at Pin No.12 of lCVR 103Ad just for 19 kHz t50Hz on Counter.Refer to Fig. 6.2Same as aboveComposite MPX Sig-nal 1 kHz on LeftChannel ONLYAC Voltmeter con-nected for TAPEOUT Jack of RightChannelVR 102(Separation )Adjust for minimumreading.Refer to Fig. 7.3Same as aboveCo

35、mposite MPX Sig-nal 1 kHz on RightChannel ONLYAC Voltmeter con-nected for TAPEOUT Jack of LeftChannelSame as aboveSame as above4Repeat Steps 2 and 3 until AC Voltmeter reading is at least -33 dB re same channel output(i.e., 33 dB separation).5Same as Step 1Composite Signal1 kHzAC Voltmeter con-necte

36、d to TAPEOUT JackSelect value ofR179Withl 0trrV antennainput signal, stereo in-dicator lamp shouldcome on.FM STEREO ALIGNMENT SET-UPFM ANTTERMINALDUMMYAC VOLTMETERTAPE OUTJACKFREOUENCYCOUNTER16 15 14 13 12 11 r023 4 5 6 7IFigure 6-9-Figure 76 LEVEL DIAGRAMAUDIO FREOUENCY= I kHzTHE VALUE SELECTED PAR

37、TSThe value of some parts is selected at the factory for optimum operation. lf the circuitry does notoperate properly, you can change these values.C101: ln some case, oscillation may take place in FM reception. Removing this capacitor may stoposcillation.R128: This is to control level of local oscil

38、lator. Use larger value to decrease level.R160: As noted on page 7, this is to control AM Signal Strength Meter. Use larger value to decreaseMeter deflection.R179: Use smaller value to increase FM STEREO indicator sensitivity.m3z(9UJ(9qoSPEAKEROUT35,5dB2,SmV= OdB-10-7 TROUBLESHOOTINGSYMPTOMCAUSE/REM

39、EDY1 ) No output.1. Faulty AC power cordReplace the cord.2. Defective power switchReplace the switch.3. Broken wire in the power transformerReplace the transformer.2) Pilot lamp does not light.1. Broken lampReplace the lamp.2. Open in the power transformer tertiary windingReplace the power transform

40、er.3 ) Pilot lamp lights but no speaker output.1. Defective capacitor C403Replace the defective capacitor.2. Defective diode D401 ,402,403 or 404Replace the defective diode(s).3. Defective in the power transformer secondary windingReplace the power transformer.4) Blows fuse.1. Defective diode D401-4

41、O4 in the rectifier circuitReplace the defective diode(s).2. Short-circuit in the rectifier circuitRemove the short.3. Short-circuit in Main Amp circuitryRepair circuit and/or replace the defective power lC 3015-1) No output one channel with VOLUMEat maximum and BALANCE at center,when a test signal

42、is applied to the ter-minal of non-operating channel of theBALANCE control VR2O2.1. Defective transistor TR205,206 or TR301-308Replace the defective transistor(s).2. Defective resistor or capacitor of TONE or MAIN AMPcircuitReplace the defective part(s).3. Defective power lC 301Replace the power lC.

43、5-2) No output when a test signal is ap.plied to the input terminals.1. Defective transistor, resistor or capacitor of PRE AMPcircuitReplace the defective part(s).2. Defective MONO/STEREO switchReplace or repair the switch.3. Defective Selector switchReplace the Selector switch.6) Speaker works norm

44、allyphone does not work.buthead-1. Defective R601 (left) or R602 (right)Change it.7) All the inputs work normally exceptAUX input.1. Poor contact in AUX input jackReplace or repair it.2. Defective resistor R501, 502, 503, or 504Replace it.3. Poor contact in Selector switchRepair or replace the switc

45、h.8) PHONO input not operative.1. Poor contact in PHONO input jackRepair or replace it.2. Faulty Selector switchRepair or replace the switch.9) TAPE OUTinoperative.1. Poor contact in TAPE OUT output jackRepair or replace it.- 1t -SYMPTOMCAUSE/REMEDYt0) No AM or FM.(TUNER B+ voltage is not 11-12Vl,.1

46、. Broken tertiary winding in the power transformerBeplace the transformer.2. Defective diode D405Change the defective diode.3. Faulty capacitor C4O2,4A4 or 405Change it.4. Defective resistor R401 or 403Replace the resistor.5. Zener diode D406 defectiveReplace the diode.6. Short circuit in TUNER B+ c

47、ircuitRemove the short.7. Poor contact in Selector switchRepair or replace it.11) No FM.1. Poor contact in Selector switchRepair or replace it.2. Defective resistor or capacitor of FM Tuner circuitReplace the defective part(s).3. Transistor, diode, lFT, resistor or capacitor of FM Tuner& lF board de

48、fectiveReplace the defective part(s).4. Faulty FM Antenna leadin/circuitryRepair or replace the Antenna lead-in/circuitry.12) No AM.1. Poor contact in Selector switchRepair or replace the switch.2. Transistor, diode, lFT, resistor or capacitor of AM lF de-fectiveReplace the defective part(s).3. Bar-

49、Antenna coil defectiveRepair or replace it.13)No MPX separation.1. lmproper adjustmentReadjust it.2. lC of MPX board defectiveReplace the lC.3. VR102 or 103 (Trimmer resistor) defectiveReplace it.14) No stereo light.1. Broken ST. indicator lampReplace the lamp.2. Defective lC of MPX boardChange the

50、defective lC.3. lnadequate value of R179Try changing value.15) FM STEREO does not work.1. Defective lC (LA 3350)Replace it.2. Defective VRl02 or 103Replace it.3. Defective transistor, resistor, capacitor or diode of FMMPX circuitReplace the defective part(s).4. Defective pilot lamp PL6Replace it.16)