Realistic-STA85-rec-sm 维修电路原理图.pdf

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1、ruLrstC.SeruiceSTA.85AM /FM STEREO RECEIVERCatalog Number:31 -2061 cusloM MANUFACIURED FoB RADIo sHACK|R orvrstoN 0F rANDy conponAloNRadioFans.CN 收音机爱 好者资料库CONTENTSSPECIFICATIONS 3 & 4BLOCK D|AGRAM. . 5D|SASSEMBLY TNSTRUCTTONS . . 6DIAL STRINGING DIAGRAM . 6ALIGNMENTPROCEDURE 7_9LEVEL DTAGRAM . . 10

2、ALIGNMENT & CHECK POINTS . 11TROUBLESHOOTTNG . . 12 _ 160055 TUNER 8OARD. . 17 & 186053 AUDTO AMp BOARD . 19 & 20SEMICONDUCTOR LEAD IDENTIFICATIONS. 21ELECTRICAL PARTS LISTMISCELLANEOUS PARTS LISTSCHEMATIC DIAGRAM SEPARATE SHEETEXPLODED VIEW SEPARATE SHEET1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.22-2930,

3、lRadioFans.CN 收音机爱 好者资料库SPECIFICATIONSNOMINALLIMITUNITFM SECTION1. TUNING COVERAGE2. DIAL CALIBRATION ACCURACY 90 MHz98 MHz3. usABLE sENsrrvrrY 106 MHz(NOTSE & DTSTORTTON -30 dB)4. IMAGE REJECTION (at 98 MHz)5. lF REJECTION (at g0 MHz)6. FULL LIMITING (at -3 dB)7. lF BANDWIDTH (6 dB down)8. DISTORTI

4、ON (1 mV INPUT)9. SIGNAL-TO-NOISE RATIO (1 mV INPUT)10. DE-EMPHASIS 75 trrsec. (at 50-10000 Hz)11. DISCRIMINATOR BANDWIDTH (Peak-to-Peak)12. AFC HOLDING RANGE (with 1 mV signal)13. OUTPUT VOLTAGE MONO(at 75 kHz dev.,400 Hz mod., 1 mV input) STEREO14, MUTING THRESHOLD15. OVERLOAD THD (at 98 MHz, 100%

5、 mod.)100 mV RF INPUT16. SPURIOUS RESPONSE at 98 MHzANTENNA INPUT 3pV,1l2 1F,103.35 MHz17. CAPTURE RATIO (1 mV INPUT)18. ALTERNATE CHANNEL SELECTIVITY(100 pV INPUT)M PX SECTION1. STEREO SEPARATION 100 Hz(100% mod., 1 mV input) 1 kHz10 kHz2, DISTORTION(100% mod. 1 mV input) 1 kl.z3. STEREO BEACON SEN

6、SITIVITY (pilot 7%)4. RESIDUAL 19 kHz & 38 kHz (1 mV input)5. SUPPRESSION OF SCA INTERFERENCE(1 mV input)AM SECTION1. TUNING COVERAGE2, DIAL CALIBRATION ACCURACY 600 KHZ1,000 kHz1,400 kHz3. USABLE SENSITIVITY 600 kH2,1000 kHz, 1400 kHz(400 H2,30% mod., Radiatednoise & distortion -20 dB) Direct4. IMA

7、GE REJECTION (at 1,400 kHz)5. lF REJECTION (at 600 kHz)6. AGC FIGURE OF MERIT(from 100 mV/m at 1,000 kHz)7, DISTORTION(400 Hz, 30% mod., 5 mV/m input)L IF BANDWIDTH (6 dB down)9. OUTPUT VOLTAGE(1 kHz 30% mod., 5 mV/m input)87.5-108.50.365r1.5400r100075065051802.0650802.O2503840300.51050250253530451.

8、5510-166025088-108t2501350r2503.01045703.0t1 500.858!2300180075012 dB650t2 dB4-161.5703.5402732201.23-164040520-1620r15t30t402.56-1420050040302530MHzkHzkHzkHzprVdBfdBdBpVkHzo/odBdBkHzkHzmVmVpVo/odBdBdBdBo/odBdBkHzkHzkHzkHzpV lmpVdBdBdBo/okHzmVpVdBdBNOMINALLIMITUNIT11.12.10. AUDIO RESPONSE(5 mV/m inp

9、ut from 400 Hz to 3 kHz, 0 dB 1,000 kHz)SELECTIVITY 200 pYlmSIGNAL.TO-NOISE RATIO(1000 kHz, with antenna input 5 mV/m)AM BEAT (input 5 mV/m)AUDIO SECTION1. RMS OUTPUT POWER(distortion (:0.3o/o,20 Hz - 20 kHz)PER CHANNEL DRIVEN 8 OBOTH CHANNELS DRIVEN 3 3(lHF power 1 kHz,8 Sl, t1 dB)4 O2. IM DISTORTI

10、ON(at 25 W output TO|T,OOAHz 411l3. HARMONIC DISTORTION lat 25 W output)100 Hz1,000 Hz10,000 Hz4. FREOUENCY RESPONSE(AUX, 8 Sl load, 1 W output, 30 Hz - 20 kHz)5. INPUT SENSITIVITY (for 35 W output) PHONOAUXTAPE MONPHONOAUXTAPE MONBASS 100 HzTREBLE 10 kHz8. EOUALIZATION RIAA: 30- 15,000 Hz9. PHONO A

11、MP OVER LOAD CAPABILITY (at 1%)10. HIGH FILTER11. LOUDNESS COMPENSATION (volume -30 dB)12. CHANNEL SEPARATION(AUX input 100 - 10,000 Hz)13. SIcNAL-TO-NOISE RATTO (input shorted)PHONOAUX14. RESIDUAL NOISE15. LOAD IMPEDANCE16. POWER SOURCE20 WATTS, No Signal170 WATTS, Full Signal120 Volts,60 Hz AC*13.

12、6. INPUT IMPEDANCE7. TONE CONTROL10 kHz10 kHz100 Hz-42840505540450.20.10.1o.2r12.818018050K70K70Kr10tg120-64104060701.5-6203210404535350.50.150.150.3r1.52.810.51 80r401 80r40!10!2!8!2RIAAt2100-6!24!210t235556034-16dBdBdBo/oWWWWo/oo/loo/loo/odBmVmVmVohmohmohmdBdBdBmVdBdBdBdBdBdBmVohm* 2201240 VAC, 50

13、 Hz for European and Australian Models.NOTE: Nominal Specs represent the design specs; all units should be able to approximate these-somewill exceed and some may drop slightly below these specs. Limit Specs represent the absoluteworst condition which still might be considered acceptable; in no case

14、should a unit performto less than within any Limit Spec.4BLOCK DIAGRAM;o= E PHi E-.dr =E9 t-Jt AE E:; *E EeeH:=3_lEal-=*=:ll5I;I+tt=t.Ftt=33;=z=LA- E-,-:-.,:=e=I=rtEr-3t=:=F-= E3-t=AF=FtEl=Esat=t- _-=ts= oI =,s9lt6_,*lll_lIFzq;6t-o=33!,9=-r-III_l_1i;=.lil-rt=qo-Eo-rIIEEIIr=t=l!l_l_J&*I=l=oo= : E= E:

15、=:g = E=E:=DISASSEM BLY INSTRUCTIONS1. Removing chassis from wooden cabinet. (Refer to Fig. A)Remove the five screws (#58 & #66) from both sides of the wooden cabinet and back panel.2. Removing the Front Panel. (Hefer to Fig. A)a) Remove the knobs from SELECTOR, SPEAKERS, BASS, TREBLE, Tuning and VO

16、LUME.b) Remove six screws (#65) from both side of Front Panel and remove panel.(rCa,lA)D*Fig. A(BDIAL STRINGING DIAGRAMNote: Tuning capacitor should be in fully closed position.d-/:_earrurrnc srarr zfALIGNMENT PROCEDURESDo not attempt alignment unless the following equipment is available.Note: Remov

17、e line cord antenna from FM external antenna terminal1. AM Signal Generator2. Oscilloscope3. AC Voltmeter4. FM Signal Generator5. Stereo Modulator6. Audio Generator7. Distortion meter8. DC Voltmeter9. Frequency Counterwhen aligning.AM IF & RF ALIGNMENTRECEIVERLoop AntennaL451Fis. 1 AM ALIGNMENT CONN

18、ECTIONTAPE OUT-lOutput of signal generator should be no higher than necessary to obtain an output reading.Signal Generator Modulation: 30%Set SELECTOR switch SWl to AM.STEPSIGNALGENERATORCOUPLINGSIGNALGENERATORFREOUENCYR ECEIVERDIALSETTINGINDICATORADJUSTMENTRefer Fig. 4.REMARKS1Refer Fig. 1455 kHz(4

19、00 Hz Mod.)Point of non-i nterference(on/about600 kHz)AC Voltmeterto TAPE OUTjackT402 flFT)Adjust for maxi-mum reading.2Same as Step 1600 kHz(400 Hz Mod.)600 kHzSame as Step 1L402 (OSC Coil)1451 (ANT Coil)Same as Step 13Same as Step 11400 kHz(400 Hz Mod.)1400 kHzSame as Step 1TC1 05(OSC Trimmer)TC1

20、04(ANT Trimmer)Same as Step 14Same as Step 11000 kHz(400 Hz Mod.)1 000 kHzSame as Step 1vR402Adjust for 160mV Audiooutput.5Same as Step 11000 kHz(400 Hz Mod.)1000 kHzReceiversSIGNALMeterVR4O1Adjust lor 70o/oreading of fullscale with inputof 5 mV/m.Note: Remove line cord antenna from FM external ante

21、nna terminal when aligning.7FM RF AND IF ALIGNMENTZin = 50 o (75 o)FM Dummy Antenna to 300 S) antenna terminal of ReceiverZout = 3OO Sl (balanced)8Signal generator output should be no higher than necessary to obtain an output reading.set selector switch to FM.Signal Generator deviation: 75kz NOTE: B

22、e sure to disconnect FM line cord antenna during alignment.STEPSIGNALGENERATORCOUPLINGSIGNALGENERATORFREOUENCYRECEIVERDIALSETTINGINDICATORADJUSTMENTRefer Fig. 4.REMARKS1Connect to FMAntenna Termi-nal throughFM DummyAntenna(300 O) Fig. 290 MHz(400 Hz Mod.)90 MHzAC Voltmeterconnected toTAPE OUTjackL10

23、1(ANT. COIL)L102(RF COIL)L 103(OSC. COIL)Adjust for maxi-mum reading onAC Voltmeter.2Same as Step 1106 MHz(400 Hz Mod.)106 MHzSame as Step 1TC1 O1(ANT. Trimmer)TC1O2 ,(RF Trimmer)TC1 03(OSC. Trimmer)Same as Step 1Repeat steps 1 & 2 until no further improvement is possible.3Same as Step 190 MHz(400 H

24、z Mod.)90 MHzSame as Step 1T101 flFT)Same as Step 14Same as Step 198 MHz(400 Hz Mod.)98 MHzDC Voltmeterconnectacross R21 1(s.9 Ks,)T201(Bottom Core)Adjust for zeroreading on DCVoltmeter.5Same as Step 198 MHz(400 Hz Mod.)98 MHzDistortionMeter con-nected toTAPE OUTjackT201(Top Core)Adjust for mini-mum

25、 distortion.6Same as Step 198 MHz(400 Hz Mod.)98 MHzReceiversSIGNALMeterVR2O3Adjust for 70o/oreading of fullscale with inputof 1 mV.7Same as Step 198 MHz(400 Hz Mod.)98 MHzOscilloscopeconnect toTAPE OUTjackVR2O4Adjust so outputjust appears withan input signallevel of 5 pV.For European model, the low

26、est frequency of FM tuning range should not be below 87.5 MHz.125 sl (112.5 s)50 a (75 a)150 r,Fis.2 FM DUMMY ANTENNAMPX ALIGNMENTTAPE OUTFM ANTENNATE RM I NALRECEIVER(300 s,)tr-Fig.3 MPX ALIGNMENT CONNECTIONMAIN AMPLIFIER ALIGNMENTFRONT ENDL103, L101L102, TC101TCl02, TC103FM SIGNALGENERATORFM DUMMY

27、ANTENNA300 f2FM IFT201VR2O3vR2o,4STEREOMODULATORSet SELECTOR Switch to FM.Tune for 98 MHz on band.Signal Generator output level: 1000pV. Deviation: 75kHz, at 100% modulation of composite signal.Connect Signal Generator to FM Antenna Terminal through FM Dummy Antenna (300 S.).ST EP19 kHz(PILOT SIGNAL

28、)MODULATIONLevelSIGNALGENERATORFreq. Set toOUTPUTINDICATORConnected toADJUSTRefer Fig. 4ADJUSTFORNOTE18ToComposite 1 kHzR channelAC Voltmeter toTAPE OUT jackof R channelAdjust input foraudio output ofabout 0.65 V28%Composite1 kHz L channelAC Voltmeter toTAPE OUT jackof R channelVR301MinimumAC Voltme

29、terreading shou ldbe at least 30dB below readingin step 1.38YoComposite1 kHz R channelAC Voltmeter toTAPE OUT jackof L channelVR301MinimumSame as Step 2.4PILOT OFFCarrier onlyFrequencyCounter Connectto TP (#10 pin)of PCB 0055 andgroundVR3O219 kHzlf you did not obtain -30 dB readings in steps 2 and 3

30、 (compared with step 1), readjust VR301 until you obtain -30 dBreading for both steps 2 and 3.INDICATORADJUSTMENTREMAR KSDC VoltmeterVR601 a. bAdjust for 0.005 V - 0.015 V acrossR623 a, b with no signalLEVEL DIAGRAMAUX : FM: AMSELECTORctr=,=50=C9UJ(9 40O30FRE0UENCY AT. 1 kHz16.7V35W/8s,oEclIVoE6l(oc

31、oPH(NO INPUT10ALIGNMENT & CHECK POINTSL402VR4O1TC105TC 104TC101TC102TCl 03T10lVR2O3VR2O4TP(N0.10 Pin)V R302FIGURE 4NOTE: This Receiver has built-in over load thermal protection for abnormal operation.When the temperature of the thermal protector (installed with heat sink) does rise abnormally(9015C)

32、, the thermal protector will automatically cut out, and as soon as the temperature goesdown suff iciently (35115C), the thermal protector turns back on automatically.lf the Receiver doesturn itself off, check ventilation and speaker connections.L101L1 02L1 03Heat Sink of PowerTransistorsPOWE RTRANSF

33、ORI4ER11V8601 a-t-tlr:tvl:i& diPR0TEcr0RAC OUTLETTROUBLESHOOTINGSYMPTOMCAUSE AND REMEDY1) Receiver not operative; pilot lampdoes not light.A) Faulty AC power cordReplace the cord.B) Defect in the power switchReplace the switch.C) Broken wire in the power transformer.Replace the transformer.D) Broken

34、 power fuseReplace the fuse.2l Fuse blows when power is turned on.A) Power Transformer T851 defectiveReplace the transformer.B) Short in the primary or secondary of the transformercircuitryRepair the short.C) Damaged rectifier D801Replace the rectifier.D) Short-circuit in the rectifier circuitRepair

35、 the short.E) Short circuit in power transistor TR609a, b orTR610a, bReplace the defective transistor and check circuit.3) Pilot lamp does not light.A) Defective lamp(s)Replace lamp(s).B) Open in the transformer T851 tertiarywindingReplace the transformer.4) Pilot lamp lights but no sound fromeither

36、 channel.A) Resistor R801, R807, R508, R509, R904 0r R915openReplace.B) Capacitor C507, C508, C801, C802, C807 or C808defectiveRep lace the defective capacitor(s).C) Diode D801 damagedReplace the diode.D) Open in secondary winding of the power trans-former T851Rep lace the transformer.5) A Speakers

37、do not work.A) Speaker switch SW8 defectiveReplace the switch.6) B Speakers do not work.A) Speaker switch SW8 defectiveReplace the switch.12SYMPTOMCAUSE AND REMEDY7l One channel does not work withVOLUME at maximum, with a testsignal applied to the center terminalof VOLUME control (VR551 orVR552) of

38、the dead channel.A) Defect in transistor TR901, TR902 or TR903 ofAudio Amp Board 6053Locate and correct the defect.B) Defect in transistor TR601-TR610 of Audio AmpBoard 6053Locate and correct the defect.C) Break in copper foil of printed circuit board 6053Repair or replace circuit board.D) Short in

39、speaker output terminalRepair the short.E) Defective resistor R903, R904, R906, R907, R914,R915, R603-R606, R609, R610, R615, R620-R627Replace the defective resistor(s).8) Same as 7 above but channeloperates when test signal is appliedas 7.A) Defective lC 1C501Replace the lC.B) Faulty resistor R503,

40、 R504, R508 or R509Replace the faulty resistor(s).C) Faulty capacitor C501 or C506Replace the faulty capacitor(s).D) Defective selector switch SW1Repair or replace the switch.9) Speaker works normally but head-phones do not work.A) Headphone plug does not mate with jackReplace the plug.B) Defective

41、resistor R629a, bReplace the resistor.10) All inputs work normally exceptAUX input.A) Poor contact in AUX input jackRepair or replace the jack.B) Poor contact in selector switch SW1Repair or replace the switch.1 1) PHONO input not operative.A) Poor contact in PHONO input jackRepair or replace the ja

42、ck.B) Faulty selector switch SW1Repair or replace the switch.C) Defective lC 1C501Replace the lC.12l, TAPE OUT not operative.A) Defective contact in TAPE OUT jackRepair or replace the jack.13SYMPTOMCAUSE AND REMEDY13) FM does not operate.A)Defective resistor R 107, R114, R207, R316, R317or R235.Repl

43、ace the defective resistor(s).Short circuit in Tuner B+ circuitRepair the short.Poor contact in selector switch SW1Repair or replace the switch.Defective diode D201Replace the diode.Capacitor C301 defectiveReplace the capacitor.Defective transistor TR201 or lC 1C201Replace the defective component.De

44、fective IFT T201Replace the lFT.Defective capacitor C2 1 1Replace the capacitor.Defective transistor TR 101, TR 102, TR 103 or CoilL101, L1O2, Ll03 of Tuner Board 0055Replace the defective component(s).Faulty lead-inRepair or replace the lead-in.Bc)D)E)F)G)H)t)J)14l Poor multiplex separationA) lmpro

45、per adjustmentReadjust T2O1, VR301 and VR302.(Refer to MPX ALIGNMENT on page 9)B) Defective lC 1C301Replace the lC.C) Variable resistor VR301 or VR302 defective.Replace the variable resistor(s).15) Stereo indicator does not light.A) Defective LED D303Replace the LED.B) Defective lC 1C301 or resistor

46、 R322 of Tuner board0055Replace the defective component(s) .C) Defective diode D301Replace the diode.16) FM volume not sufficient.A) lf volume of both L and R channels not enoughFront End defective, or faulty transistor TR201lC 1C201, IFT T201 or diode D2O3, capacitorC211 or faulty TR301, TR302, tC3

47、01 or C301of Tuner Board 0055Replace the defective component(s).B) lf sound of one channel not enough: DefectiveL301 in case of L channel, or defective L302 incase of R channelReplace the defective coil.14SYMPTOMCAUSE AND REMEDY17l AM does not operate.Damaged 1C401 of Tuner Board 0055Replace 1C401.D

48、efective L4O1, L404, T401 or T4O2 of TunerBoard 0055Replace the defective component(s).Defective diode D401 or D4O2 of Tuner Board 0055Replace the defective diode(s).One of resistors of Tuner Board 0055Replace the defective part.One of capacitors of Tuner Board 0055Replace the defective part.Selecto

49、r switch SW1 defectiveRepair or replace the switch.Defective Tuning GangReplace Tuning Gang.Damaged AM bar antennaRepair or replace the bar antenna.A)B)c)D)E)F)G)H)18) LOUDNESS has no effect.A) Defective LOUDNESS Switch SWsReplace the switch.B) Defective C701 or R703Replace defective component(s).C)

50、 Defective VOLUME control VR551 or VR552Replace.19) STEREO-MONO not effectiveA) Defective MONO switch SW4Replace the switch.2Ol TAPE MONITOR noteffectiveA) Defective TAPE MON switch SW3Replace the switch.B) Poor contact in TAPE lN input jacksRepair or replace jack.C) Resistor R702 defectiveReplace t