Realistic-STA7-rec-sm 维修电路原理图.pdf

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1、laLtstrClSerulceAM /Fwt SCatalogSTA-7TEREO RECEIVERNumber:31 -1 968cusroM MANUFACTURED FoR RADIo sHACK f,n DMSIoN 0F rANDy conpoRAloNRadioFans.CN 收音机爱 好者资料库(1)(21(3)(4)(5)(6)PAGEELECTR ICAL PERFORMANCE SPECIFICATIONS3-4BLOCKDIAGRAM. -.5DISASSEMBLY INSTRUCTIONS . ., , .6-7CIRCUIT OPERATION CHECK . .

2、.8_16ALIGNMENT INSTRUCTIONS ,. . .17_20BUILT.IN PROTECTOR CIRCUIT DESCRIPTION(MA|N AMP tC HA-1370) . . .20(7) TROUBLESHOOTING. .21_23(8) VALUE SELECTED PARTS ,.,23(9) D|AL STRINGTNG D|AGRAM. .24(10) LEVEL DTAGRAM .25(T1) IC&TRANSISTOR LEAD IDENTIFICATION ,.25(12) AM/FM RF rF, MPX & PRE, TONE AMP P.C

3、.B. (TOp&BOTTOM VTEWS). .26-27(13) MA|N AMP & POWER SUPPLY P.C.B. (TOP & BOTTOM V|EWS) .28(14) SPEAKER JACKS & SYSTEM/FLAT EOUALIZATION P.C.B.(TOP & BOTTOM VIEWS) .,.29(15) MONTTOR SWTTCH P.C.B. (TOp V|EW) . .30(16) SPEAKER SWITCH P.C.B. (TOP VIEW) . . . . .3O(17) ELECTRTCAL PARTS L|ST 31-37(18) EXP

4、LODED VIEW PARTS LIST . . 38-39(19) rC TNTERNAL DTAGRAM (LA3350 & HA-1370) . . 40-41(20) SCHEMATTC DTAGRAM . . 42-43(21) EXPLODED VIEW 44_45t*/Iv-I,IIIl-2-RadioFans.CN 收音机爱 好者资料库1 . ELECTRICAL PERFORMANCE SPECIFICATIONSAM BANDFrequency CoverageIFAntenna Sensitivity for S/N 20 dB at 600 kHzat 1000 kH

5、zat 1400 kHzTerminal Sensitivity (20 dB S/N)ACA at S/N 6 dB Sensitivity at 1000 kHzS/N Ratio at 5 mV lnputAGC Distortion at 1000 kHz,100 mV/m lnput,80 % mod.AGC Figure-of-MeritlF Rejection at 600 kHzlmage Rejection at 1400 kHzDistortion at 5 mV/m, 30 % mod.Tape Out Level 5 mV/m lnput, 3A% 4OOHzFidel

6、ity 5 mV/m lnput, -O dB down (1 kHz = 0 dB)Whistle Modulation of 2nd and 3rd Harmonicat 1000 pYlm and 5000 pVlmCalibration at 600 kHzat 1000 kHzFM BANDFrequency CoverageIFIHF Sensitivity at 90,98 and 106 MHzFM S/N Ratio at 98 MHz, 1 mV lnputFM Limiting Sensitivity (-3 dB)lF Rejection Ratio at 90 MHz

7、lmage Rejection Ratio at 106 MHzCapture Ratio at 90 MHz, 1 mV lnputACA -+. 400 kHz, 100 pV lnputAudio THD 400 H2,75 kHz dev.Calibration Accuracy at 90 MHzat 106 MHzAFC Holding Range with 1 mV lnputAM Suppression, AM - 30%, FM - 10O%Maximum Signal Handling CapacityTape Out Level, 75 kHz dev. 1 mV lnp

8、utAll sets must meet the requirements of FCC.Frequency response must meet the 75 psec de-emphasis(50 psec de-emphasis for Australian models).FM MPX SECTIONStereo I ndicator SensitivitySeparation at 1 mV lnput at 100 Hzat 1 kHzat 10 kHzStereo Distortion at 1 mV 1 kHz38 kHz RejectionSCA RejectionStere

9、o Output Level(UL, C.S.A.)UNIT(pV)(dB)(dB)(dB)%t(dB)(dB)(mV)UNIT(kHz)(kHz)fuV/m)(pVlm)(pVlm)(pv)(dB )(dB)(/1(dB)(dB)(dB)%t(mV)(Hz)%t(kHz)(kHz)UNIT(MHz)(MHz)(pV)(dBf)(dB)(pv)(dB)(dB)(dB )(dB)e/,1(kHz)(kHz)(kHz)(dB )(mV)(mV)NOMINAL510-1650455200200200102840445.32451.521020-3000NOMINAL86.5- 108.510.72.

10、814.2603.2BO503450.5r2503B200630L!MIT520-16205005005002034103827353.5210 L 2.5 dB50-250015r_25i.50LIMIT88- 1 085.019.2557.170456301.0r 500r 500r.33030100630 r 2.5 dBLIMIT2022272A2.O48560 r 2.5 dB8NOMINAL102934260.65580560-3-NOTE: Set Equalizer Switch to FLAT position unless otherwise specified.AUDIO

11、 SECTIONlnput lmpedance PHONO Mag.AUXOutput Power THD 1 o/o,81, Both Channels Driven at 1 kHzPower Bandwidth, 8 O, Both Channels Driven, underTHD 0.5 %20Hz to 20 kHz (THD 0.7 o/ofor 4 a load)Sensitivity for Rated Power (10W) PHONO Mag.AUXTape lnFrequency Response at AUX, Output Power 1 W, 4.2 dBBass

12、 Action at 100 HzTreble Action at 10 kHzMin. Volume Hum and NoiseMax. Volume Hum and Noise at AUX (Tone Max.)Signal-to-Noise Ratio PHONO Mag.(lnput shorted)AUX (lnput terminated with 4.7 KAICross Talk at 1 kHz, AUX positionBass Compensation at 100 Hz-30 dB VOLUME PositionTreble Compensation at 10 kH

13、z-30 dB VOLUME PositionTape Out LevelPHONO Mag. 2.2mV tnput, 1 kHz)AUX (160 mV lnput, 1 kHz)PHONO Mag. Equalizer Response at 100 Hzat 10 kHzPHONO Mag. Overload at 1 kHzTape Out Level (DlN) (3.3 KO Terminated)AM 5 mV/m lnput 30 % mod.FM 1 mV lnput, 22.5k1z dev. 400 HzAUX22O mV lnputFrequency Equaliza

14、tion flesponse in SYSTEM positionat 100 Hz, lnput AUXMusic Power at THD 0.9 Yo, 1 kHz (Australian models),dUNIT(Ko )(Ksl)(w)(w)(mV)(mV)(mV)(Hz)(dB)(dB)(mV)(mV)(dB)(dB)(dB)(dB)(dB)(mV)(mV)(dB)(dB)(mV)(mV)(mV)(mV)(dB)(w)NOMINAL5010014122.216016015-30 k*.10a.1016606546+6LIMIT12102.2 r.2 dB160i2dB160r 2

15、 dB20-20 k* 10 +. 2.5 dBn 10r.2.5 dB315555540+6 n 2.5 dB+4.5 +4.5 +.2.5 dB150 150a.2 dB150 150r.2 dB+13.11 +13.11*.2d8-13.75 -,13.75 r-2 dB100 803.3 3.3 *.3 dB3.3 3.3 +. 3 dB3.3 3.3 a.3 dB+6.5 +6.5 +. 2.5 dB18 15NOTE:The supply voltage is l20voltsAC (for UL & C.S.A.) and24OvoltsAC forAustralian mode

16、ls,from a regulated power supply.The power source must be isolated from other equipment connected to antenna or output.The room temperature is 25 degrees C.Nominal Specs represent the design specs; all units should be able to approximate these - somewill exceed and some may drop slightly below these

17、 specs.Limit Specs represent the absolute worst condition which still might be considered acceptable;in no case should a unit perform to less than within any Limit spec.*4-2. BLOCK DIAGRAM-lIrtl)UzzrGtIdJoUEFtUzfFr=ca6ffoooNGFJlUIzlz)lIIolrlJlblzl21t :l .ula(EI ILYtiJzz-GoF_lJIulzlzlztxo=B=1=N-aF3E;

18、uc-3?so66otrEoB+siE-=B:gE- oi!*o=FxE-aEO=6=8;E-5-nWritlur ttltr!rr!|ffi ffi,illilillr rilr$trill;1ill-III3. DISASSEMBLY INSTRUCTIONSFigure A1)To remove chassis from MetalCabineta) Turn the Cabinet upside down and re-move the six screws from the Cabinetbottom. (Figure A)b) Remove the five screws from

19、 the RearPanel. (Figure B)Figure C12) Removal of Front Panela) Remove the chassis from Metal Cabinetas described in 1).b) Pull off the Metal Cabinet.c) Remove two screws each from the topand bottom of the Front Panel.(Figure C1, Czld) Remove the two screws from the back ofFront Panel. (Figure D)e) R

20、emove Knobs and pull off Panel.Figure BFlgure C2-6*Figure D3)To remove two bottom coversi) Removal of Bottom Cover Remove the six (A) screws from bottomcover as shown in Figure E.ii) Removal of Bottom Cover ERemove the six (B) screws from bottomcover as shown in Figure E.IA(A),l1*B+(B),lar*t*r*-(B)

21、,-(A)Figure E4)To remove Rear Panel from chassisa) Remove bottom covers as described in 3).b) Remove the two screws from bottom ofRear Panel. (Figure F)c) Remove the four screws frorn the RearPanel. (Figure G)Figure FFigure G-7 -STARTCONNECTION4. CIRCUIT OPERATION CHECK1)POWER SUPPLY OPERATION CHECK

22、Connect AC Cord to 120 V AC, 60 Hz (UL, C.S.A.l (24O V AC, 50 Hz for Australian)Check the Power Supply voltages. (Figure 1)Check the Power Supply circuits, Fuse and Power Transformer.DC voltages are not correct.DC voltages are correct.Proceed to next section.2)AUDIO SECTION OPERATION CHECK(1) MAIN A

23、MP. OPERATION CHECKConnect 8 O Load to Speaker Output.Connect DC Voltmeters to Pin No. 3 of MAIN lC 401 (lC4O2) and ground (PlusSupply) and Pin No. 10 and ground (Minus Supply). See Figure 2.MAIN AMP EOARDDC VOLTMETERFigure 2Check Power Supply Voltage with No lnput (must be r21.2V).Check D501-504, C

24、505, 506.Check for short-circuits.DC Voltage is not i 21.2 V .DC Voltage is r21.2Y.9.7Vltto a 6CONNECTIONREPAI R-8-CONNECTIONNECTIONREPAIRConnect 8 o Load to Speaker Output.Check Pop Muting circuit included in MAIN Amp lC 401about 2-3 seconds after Power is Switched an,.(lC4O2l. U nit activates(1) C

25、heck MAIN Amp lC4O1l4O2.(21 Check TR504.Pop Muting circuit does not work,Pop Muting circuit works.Connect 8 O Load to Speaker Output.Connect Audio Osc. to AUX input.Connect V.T.V.M. to Speaker terminals. (Figure 3)AUDIO OSC.Check Equalization Response in SYSTEM positionposition = 0 dB). (Figure 4)V.

26、 T. V. M.at 100 Hz input. (FLATFigure 4t;e+Check the MAIN Amp Equalization circuit.See TROUBLESHOOTING.Equalization Response at 100 Hz does not fall within +6.5 i 2.5 dB.Equalization Response at 100 Hz falls within +6.5 -+.2.5 dB.to next section.Proceed-9-CONNECTIONREPAIRQI PRE.AMP OPERATION CHECKSe

27、t SELECTOR Switch to PHONO.Connect Audio Osc. to PHONO lnPut.connect oscilloscope and VT.V.M to TAPE oUT Jack (see Figure 5)AUDIO OSC. OSCILLOSCOPESETFigure 5Equalization Curve response (RIAA Curve)Check for proper PHONO(See Figure 6).I+13.rlFigure 620 -3pHgor.r,*,(1) check rR2o1, 2m (rJ;Lf irol.(21

28、 Check C209,C211,R219,R217 (L ch) and C210,C212,R22OR218(R ch).(3) Check Pre-Amp circuit.Equalization Response at 100 Hz does not fall within +13.11 r-2 dB and at10 kHz does not fall within -13.75 -+.2 dB.Equalization Response falls within +13.11 L2dB at 100 Hz and -13.75+.2 dB at 10 kHz.Proceed to

29、next section.(3) TONE CONTROL OPERATION CHECKSame Equipment Connection as Figure 3.a36U6UEt -,oIl- r3.751-15t5too-to- 10-Proceed to the next section.-11 -Check BASS(F igure 7)Action atTONE COiITROL CURVE. IOOHz + BASSt tO Nxz .+ TREBLE ,+loa;ozcu -roc1Figure 7-) AUDTO FiEOUENCY(Hz)Check Bass Control

30、 circuit on TONE CONTROLFrequency Response does not fall within a.10 r 2.5 dB.Frequency Response falls within i 10 n 2.5 dB.Check TREBLE Action at 10 kHz. (Figure 7)Check Treble Control circuit on TONE CONTROL P.C.B.Frequency Response does not fall within i 10 r.2.5 dB.Frequency Response falls withi

31、n -+.10 +.2.5 dB.Check LOUDNESS compensation(Figure 8)with Volume set for -30 dB from rated power.+632Figure 8 $*ou1.Check Loudness circuit.100 lK 10K-IAUOOFREOUENCY(HZ) LOUOTIESSGJRVELoudness compensation does not fall within +6 r. 2.5 dB at 100 Hz and+4.5 -1 2.5 dB at 10 kHz.Loudness compensation

32、falls within + 6 r 2.5 dB at 100 Hz and +4.5i.2.5 dB at 10 kHz.roKP.C.B.REPAI RREPAIRSTARTADJUSTMENTREPAIRREPAI3)AM RF/IF OPERATION CHECKAdjust AM lFlRF Alignment. (See AM Alignment Section on page 17,)Set SELECTOR Switch to AM.Connect Standard Loop Antenna to AM SG and radiate signal into the AM Fe

33、rriteAntenna L7O1.Connect Oscilloscope, Distortion Meter and V.T.V.M. toTAPE OUT jack on set.(See Figure 9.)AM SGLOOP ANTENNAFigure 9Check AM coverage: lowest Dial pointer position should be under 520 kHz andhighest position should be over 1620 kHz.Readjust AM coverage, (See page 17 for AM Alignment

34、.)Coverage is less than 520 kHz * 1620 kHz.Coverage is at least 520 kH.z - 1620 kHz.Check Antenna Sensitivity for S + N/N 20 dB at 600, 1000and 1400 kHz.Readjust AM tracking. (See page 17 for AM Alignment.)AM Sensitivity is worse than 500 pV/m.AM Sensitivity is better than 500 pYlm. (Nominal Sensiti

35、vity is 200pVlm).L_z_J AM BAR ANTENNAIteomt L/ SETI l/ f-OSCILLOSCOPE V,T.V,M, DISTORTION I/IETER-12-REPAIRR EPAI RCONNECTIONSTEP 5REPAIRCheck AM Distortion (lnput level to 5 mV/m).(1) Readjust AM lFlR F Alignment.(21 Check AM I F/R F circuit.Distortion is greater than 3.5 %.Distortion is less than

36、3.5 Yo.Check the AM Signal Meter Pointer.(1) No signal - 0 point t 0.8 m/m(21 5 mV/m lnput - 75-85 %(See Figure 10.) No TGNAL rNpur/0.8mmFigure 100.8mm75-85o/oAdjust value of R 150.Signal Meter pointer does not indicate correctly.Signal Meter pointer indicates correctly.Same equipmentconnection as F

37、igure gand set lnput level to 5 mV/m.Check AM TAPE OUT Level.Check and adjust value of R 162.TAPE OUT Level does not fall within 21O r 2.5 mV.TAPE OUT Level falls within 21O *- 2.5 mV.INPUT:5mV/mProceed to next section.-13-CONNECTIONREPAIRSTEP 2CONNECTION4) FM RF, IF & MPX OPERATION CHECKAdjust FM A

38、lignment. (See FM Alignment Section on page 18.)Set SELECTOR Switch to FM.Connect FM SG (1000 H2,75 kHz dev.) to FM 300 o Antenna Terminal.Connect Oscilloscope, Distortion meter and V.T.V.M. to TAPE OUT Jack. (SeeF igure 1 1.)OSCILLOSCOPE V,I,VM, DISTORTION METERFM EXI,ANTENNA TERI4lNAL ( 3OOo)Figur

39、e 11Check FM coverage: Lowest pointer position should be under BB MHz and highend should be over 108 MHz.(1) Readjust FM coverage. (See FM lFlRF Alignment on page 18.)(2) Check FM RF circuit.Coverage is not correct.Coverage is correct.Check IHF Sensitivity at 90, 98 and 106 MHz.Readjust FM tracking.

40、 (See FM lFlRF Alignment on page18.)Check the FM RF and lF circuits.F M lH F Sensitivity is worse than 5 pV.FM IHF Sensitivity is better than 5 pV. (Nominal Sensitivity is 2.8 pV.)Same equipment connection as Figure 11.Set Dial Pointer to 98 MHz (Minimum Distortion point).FIV SG99Aa9AaaoSET3OOoDU I4

41、MYTAF,our I IAJACK Ll-J-l)a/ r-14-15-Check the Signal Meter Pointer.(1) No signal - 0 point I 0.8 m/m.(21 1 mV lnput (Mod. - OFF)Adjust T110 for maximum reading on sets meter.(3) 100 mV lnput - 90-95% of full scateAdjust vR 101 so the Meter Pointer on set is g0-9b% of full scale.(4) Check to be sure

42、 that the max. Meter reading point is also the point of mini-mum distortion. (See Figure 12.)NO SIGNAL INPUT90- 95%Meter Pointer indicates incorrectly.Meter Pointer indicates correctly.Same equipment connection as F igure 1 1.Set FM SG to 98 MHz, 1 mV lnput.MODE Switch to STEREO.Check FM TAPE OUT Le

43、vel.Adjust value of R 1Bg (L ch) and/or R 190 (R ch).TAPE OUT Level is not 630 mV t 2.5 dB.TAPE OUT Level is 630 mV t 2.5 dB.Check TH. Distortion for Mono. signal.Readjust RF/lF Alignment on page 18.TH. Distortion is greater than 1.0%.INPUT:lOOmV/mREPAIRCONNECTIONREPAI RSTEP 6REPAIRReadjust T110 and

44、 VR 101.TH. Distortion is less than 1.0%.Proceed to next section.(3) FM MPX OPERATION CHECKAdjust for FM MPX Alignment on page 19.Same equipment connection as Figure 11.Connect FM Stereo SG to FM SG. (Figure 13)Stereo ModulationMAIN & SUB - 90% (67.5 kHz dev.)Pilot 8% ( 6 kHz dev.)Frequency 98 MHz,

45、1 kHz mod.lnput 1 mVFM STEREO SG FM SG3OOo DUMMYTAPE OUT JACKFigure 13OSCILLOSCOPE V.T.V.M. DISTORTION METERFM EXT.ANTENNA TERIVI|NAL (3ooo)Check Stereo Separation at 100,i k and 10 kHz.Check the Stereo lndicator Sensitivity.input: near 10pV)Readjust FM MPX Alignment on page 19.Check the FM MPX circ

46、uits.Stereo Separation is worse than 22 dB at 100, 27 dB at10 kHz.Stereo Separation is better than22 dB at 100, 27 dB at10 kHz.lkand20dBat1 kand20dB atAdjust value of R 167.Check FM MPX circuits.Stereo Beacon Sens. is worse than 20 pV.Stereo Beacon Sens. is better than 20pV. (Nominal sensitivity: 10

47、pV)CONNECTIONSTEP 1REPAIRProceed to Alignment section.-16-5. ALIGNMENT INSTRUCTIONSEOUIPMENT REOUIRED1. AM Signal Generator2. AC Voltmeter3. OscilloscopeTUNER(TCrOr)FM ANT.TRIMMERcorl &(TC rO4)AM ANT.TRIMMERTRIMMER LOCATIONS(TCrO2) (Tct05)FM RF AM OSC.aM osc corLfito5)f-,FM ANT.( Lrot)MYOSC TRIMMER(

48、TCr03)AM IF & RF ALIGMENTNOTE: . Signal generator output should be no higher than necessary. Maintain line voltage a,t 12O volts. (UL, C.S.A.) (Use 240 Vo Set SELECTOR Switch to AM.o See P.C.B. illustrations for alignment points/adjustments.AM ALIGNMENT SET-UPFigure-17-FM RF COIL( Ll03 )FM OSC CO|L(

49、Lro5)to obtain an output reading.for Australian models.)STEPSIGNAL GENERATORCOUPLINGSIGNAL GENERATORFREOUENCYDIAL SETTINGINDICATORADJUSTMENTREMARKS1Connect standard loopANTENNA to SignalGenerator and radiatesignal into the AMFerrite antenna.See Fig. 14.455 kHz(4OOHz,30% MOD)Point of non-interference

50、(near 600 kHz)AC Volt-meter toTAPE OUTJACKT106T 107T108T109Adjust formaximumreading.2Same as above600 kHz (400 Hz,30% MOD)600 kHzSame asaboveT105 (OSC Coil)L7O1 (AM ANTCoil)Adjust formaximumreading.3Same as above1400 kHz OAHz,30% MOD)1400 kHzSame asaboveTC105(OSC Trimmer)TCt04(ANT Trimmer)Adjust for