Realistic-STA235-rec-sm 维修电路原理图.pdf

tVSTA.235AM IFM STEREOCatalog Number:RECEIVER31-2065cusToM MANUFACTURED FoR RADIo sHAcKIn DrvrsroN 0F TANDv coRpoRATroNIRadioFans.CN 收音机爱 好者资料库CONTENTSPAGE1. SPECIFICATIONS 3- 42. BLOCK DIAGRAM . 53. DISASSEMBLY INSTRUCTIONS . 64. DIAL STRINGING DETAIL . 65. ALTGNMENT PROCEDURE . . 7 - I6. ALIGNMENT POTNTS . . 107. LEVEL DTAGRAM . 118. TROUBLESHOOTTNG . 12- 199. 5030 EO AMp BOARD . . 1910. 0042 TUNER BOARD . 2011. OO43 TONE AMP & AUTO-M BOARD .,.,. 2112. OO45 MAIN AMP BOARD .,.,.,. 2213. 6044 AUDIO DRIVER AMP BOARD . 2314. 8030 POWER SUPPLY BOARD . 2415. TRANSTSTOR & tC LEAD tDENTtFtCAT|ONS. . 2516. ELECTRICAL PARTS LIST 26 - 3317, MISCELLANEOUS PARTS LIST . .,.,. 3418. SCHEMATIC DIAGRAM . SEPARATE SHEET19. EXPLODED VIEW SEPARATE SHEETRadioFans.CN 收音机爱 好者资料库SPECIFICATIONSNOMINALLIMITUNIT1.2.FM SECTIONTUNING RANGEDIAL CALIBRATION ACCURACY 90 MHz98 MHz106 MHzUSABLE SENSITIVITY(NOISE & DISTORTION -30 dB)IMAGE REJECTION (at 106 MHz)lF REJECTION (at 90 MHz)FULL LIMITING (at -3 dB)lF BANDWIDTH (6 dB down)DISTORTION (1mV INPUT)SIGNAL-TO-NOISE RATIO (1mV INPUT)DE-EMPHASIS 75 psec. (at 50- 10,000 Hz)DISCRIMINATOR BANDWI DTH (Peak-to-Peak)AFC HOLDING RANGE (with 1 mV signal)OI.,TPUT VOLTAGE(at 75 kHz dev., 4OO Hz mod., 1MUTING THRESHOLDOVERLOAD. THD at 98 MHz, 100%(100 mV RF input)SPURIOUS RESPONSE at 98 MHzANTENNA INPUT 3 pV,1/21F, 103.35 MHzCAPTURE RATIO (1 mV INPUT)ALTE RNATE CHANNE L SE LECTIVITY(1 mV input)3.4.5.6.7.8.L10.11.12.13.14.15.16.17.18.mV input)mod.MPX SECTION1. STEREO SEPARATION(1OOo/o mod., 1 mV input)100 Hz1 kHz10 kHz2. DISTORTION1 kHz(100% mod., 1 mV input)3. STEREO BEACON SENSITIVITY (pilot 7%)4. RESIDUAL 19 kHz & 38 kHz (l mV input)5. SUPPRESSION OF SCA INTERFERENCE(1 mV input)AM SECTION3.1.2.4.5.6.TUNING RANGEDIAL CALIBRATION ACCURACY 600 kHz1,000 kHz1,400 kHzUSABLE SENSITIVITY 600 kH2,1000 kHz, 1400 kHz(4OO H2,30% mod., Radiatednoise & distortion -20 dB) DirectIMAGE REJECTION (at 1,400 kHz)lF REJECTION (at 600 kHz)AGC FIGURE OF MERIT(from 100 mV/m at 1,000 kHz)DISTORTION(4OO H2,30% mod., 10 mV/m input)lF BANDWIDTH (6 dB down)OUTPUT VOLTAGE(400 H2,30% mod., 5 mV/m input)7.8.9.87.5-108.52.O751001.50.270r 1.5400t 1,0000.980.580275510-1 7004040300.5455250207A60450.81830088-108t25Ot350t25O3.065802.Ot1500.860 x2.O300t8000.9r3 dB3-161.0703.5602530201.03-164540520-1620t15t30t40402.013-26200400305850MHzkHzkHzkHzpVdBdBpVkHzo/odBdBkHzkHzo/odBdBdBdBdBdBVpVo/opVdBdBkHzkHzkHzkHzpVlmpVdBdBdBo/okHzmVNOMINALLIMITUNIT10. AUDIO RESPONSE(5 mV/m input from 400 Hz to 2 kHz,0 dB 1,000 kHz)11. SELECTIVITY 2OOpVlm12, SIGNAL-TO-NOISE RATIO(1,000 kHz, with antenna input 5 mV/m)13. AM BEAT (input 5 mV/m)14. WIDE BAND AM THRESHOLDAUDIO SECTION1. RMS OUTPUT POWER(distortion 1. O.3o/o, 20 Hz - 20 kPzlPER CHANNEL DRIVEN 8 O4aBOTH CHANNELS DRIVEN 8 O4a2. IM DISTORTION(at 40 W output 7Ol7,OOO Hz 4l1l3. HARMONIC DISTORTION (at 40 W output)100 Hz1,000 Hz4, FREOUENCY RESPONSE 1O,OOO HZ(AUX, 8 o load, 1 W output, t1.0 dB)(AUX, 8 c| load, 1 W output, +1.5 dB, -4 dB)5. INPUT VOLTAGE (at 50 W output)PHONO-HIPHONO-LOAUXTAPE MONITORPHONO MAGAUXTAPE MONITORBASS 100 HzMIDRANGE 1.5 kHzTREBLE 10 kHz8. EOUALIZATION RIAA: 30- 15,000 Hz9. PHONO AMP OVER LOAD CAPABILITY (at 1% HDIHILOHIGH FILTERLOW FILTERLOUDNESS COMPENSATION (Volume -30 dB)50 Hz100 Hz13. CHANNEL SEPARATION(AUX input 100 - 10,000 Hz)14. SIGNAL-TO-NOISE RATIO (input shorted)PHONO MAGAUX15. RESIDUAL NOISE16. LOAD IMPEDANCE17. POWER SOURCE120 Volts,60 Hz AC*30 WATTS, No Signal320 WATTS, Full Signal22O|24OV AC, 50 Hz for European and Australian Models6. INPUT IMPEDANCE7, TONE CONTROL10.11.12.10 kHz70 Hz-325403706560650.10.030.030.0850-30k20-70k52.5210210507070t8t6r10100200-6-611I4065800.5321010-50-620605555550.30.150.150.320-40k5t12.St0.521 et30219t30t8t2x6t2x1Ot2RIAAl280160-Gt2-6x211t29x23558701.54-16dBdBdBo/omVWWWWo/oo/oo/oo/oHzHzmVmVmVmVke,kr,k(?dBdBdBdBmVmVdBdBdBdBdBdBdBmVOHMNOTE: 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 stiil might be considered acceptable; in no case should a unit performto less than within any Limit Spec.BLOCK DIAGRAMIsurlYldsts r +vl955E ssE9HS3P;=oATJ-JTJ-* =?=ir: =-;IS=ED!SASSEMBLY I NSTRUCTIONS1. Removing chassis from Wooden Cabinet. (Refer to the Fig. A.)Remove five screws-two (BB) from each side of the wooden cabinet and one(89)from the back.2. Removing the front Panel. (Refer to the Fig. A.)Remove six screws-three (89) from each side of the Front Panel and removepanel.6B-_ )-aqo*Fig. ADIAL STRINGING DIAGRAMNote: Tuning capacitor should be in fully closed positionNO SHAFTDIAL DRUI,/ALIGNM ENT PROCEDURESDo not attempt alignment unless the following equipment is available.1. AM Signal Generator2. Oscilloscope3. AC VoltmeterNote: Remove line cord antenna from FM external antenna terminal when aligning.AM IF & RF ALIGNMENT4. FM Signal Generator5. Stereo Modulator6. Audio GeneratorRECEIVER7. Distortion meter8. DC Voltmeter9. Frequency CounterTAPE OUTOutput of signal generator should be no higher than necessary to obtain an output reading.Signal Generator Modulation: 30%Set SELECTOB switch SW1 to AM.STEPSIGNALGENERATORCOUPLINGSIGNALGENERATORF R EOU ENCYRECE IVERDIALSETTINGINDICATORADJUSTMENTRefer Fig. 4.REMARKS1Refer Fig. 1455 kHz(400 Hz Mod.)Point of non-i nterfe re nce(on/about600 kHz)AC Voltmeterto TAPE OUTjackCF4O1(Both Sections)Adiust for maxi-mum reading.2Same as Step 1600 kHz(400 Hz Mod.)600 kHzSame as Step 1L401(RF COIL)L402(OSC. COIL)L451(ANT. COIL)Same as Step13Same as Step 11400 kHz(400 Hz Mod.)1400 kHzSame as Step 1TC1 O5(ANT. Trimmer)TC1 06(RF Trimmer)TC1 07(OSC. Trimmer)Same as Step 14Same as Step 11000 kHz(400 Hz Mod.)1000 kHzSame as Step 1VR4O3Adjust for 300mV on ACVoltmeter withinput of 5 mV/m.5Same as Step 11000 kHz(4 kHz Mod.)1000 kHzSame as Step 1VR4OlAdjust for 21OmV reading onAC Voltmeterwith input of28 mV/m.6Same as Step 11000 kHz(400 Hz Mod.)1000 kHzSIGNALMeterVR4O2Adjust for 80%reading of fullscale with inputof 5 mV/m.Note: Remove line cord antenna from FM external antenna terminal when aligning.TUNERFRONT ENDTC105, TC106,TC1 07L401, L402AM/FM IFcF401Fig. 1 AM ALIGNMENT CONNECTIONFM RF AND IF ALIGNMENTSignal generator output should be no higher than necessary to obtain an output reading.Set Selector switch to FM.Signal Generator deviation: 75k1z NOTE: Be sure to disconnect FM line cord antenna during alignment.STEPSIGNALGEN E RATORCOUPLI NGSIGNALGENERATORF R EOU ENCYRECEIVERDIALSETTI NGINDICATORADJUSTMENTRefer Fig. 4.R EMAR KS1Connect to FMAntenna Termi-nal throughFM DummyAntenna(300C2). Fig. 290 MHz(400 Hz Mod.)90 MHzAC Voltmeterconnected toTAPE OUTjackL1 01(ANT. COIL)L102(RF COIL)L1 03(RF COIL)Ll 04(OSC,COIL)Adjust for maxi-mum reading onAC Voltmeter.2Same as Step 1106 MHz(400 Hz, Mod.)106 MHzSame as Step 1TC1 02(RF Trlmmer)TC103(RF Trimmer)TC1 04(OSC,Trimmer)TCi O1(ANT.Trimmer)Same as Step 1Repeasteps 1 & 2 until no furtherimprovement is possible.3Same as Step 190 MHz(400 Hz, Mod.)90 MHzSame as Step 1T1 01(FM IFTSame as Step 14Same as Step 190 MHz(400 Hz, Mod.)90 MHzDC Voltmeterconnected toPin #16 and#17 on PCB#oo42L203(Pink Core)Adjust for zeroreading on DCVoltmeter.5Same as Step 190 MHz(400 Hz, Mod.)90 MHzDistortionMeter con-nected toTAPE OUTjackL203(Blue Core)Adjust for mini-mum distortion.6Same as Step 198 MHz(400 Hz, Mod.)98 MHzSame as Step 1vR202Set SE LECTORswitch to FMMUTE. Adjustfor zero readingon AC Voltmeterwith SG outputlevel of 4 pV.7Same as Step 198 MHz(400 Hz Mod.)98 MHzSIGNALMeterVR201Adjust for FullScale of SIGNALMeter with SGoutput level of2 volts.For European model, the lowest frequency of FM tuning range should not be below 87.5 MHz.1257 nD.5l,1FM Dummy Antenna to 300 Cl antenna terminal of Receiver1 50,fZin = 50sl (75o)Zout = 3O0O (balanced)Fig. 2 FM DUMMY ANTENNAM PX ALIGNM ENTTAPE OUTFM ANTENNATERMINAL(300s,)RECEIVERTUNERFRONT ENDL101, L102L103, L104T1 01 . TCl 01TC1 02, TC1TCl 04FM SIGNALGENERATOBFM DUMMYANTENNA300rlMPXVR30,IV R3O2STEREOMODULATOR_lFis.3 MPX ALIGNMENT CONNECTIONlf you did not obtain -30 dB readings in steps 3 and 4 (compared with step 2), readjust VR301 until you obtain -30 dBreading for both steps 3 and 4.MAIN AMPLIFIER ALIGNMENTSet SELECTOR Switch to FM.Tune for 98 MHz on band.Signal Generator output level: 1000 trrV Deviation: 75 kHz at 1OO% modulation of composite signalconnect Signal Generator to FM Antenna Terminal through FM Dummy Antenna (300 o).STEP19 kHz(PILOT SIGNAL)MODULATIONLevelSIGNALGENERATORFreq. Set toOUTPUTINDICATORConnected toADJUSTReferFis.4.ADJUSTFORNOTE1Frequency counterconnected to TP3and GroundVR3O276 kHz29YoComposite 1 kHzR channelAC Voltmeterconnected toTAPE OUT jackof R channelAdjust inputfor Audio outputof about 0.9V.38YoComposite 1 kHzL channelAC Voltmeterconnected toTAPE OUT jackof R channelVR301mtntmumAC Voltmeterreading shouldbe at least 30dB below read-ing in step 2.48YoComposite 1 kHzR channelAC Voltmeterconnected toTAPE OUT jackof L channelVR301mtntmumSame as Step 3INDICATORADJUSTMENTREMARKSDC VoltmeterVR601a, bAdjust for 0.005-0.015 volts acrossR626a, b with no signal.IALIGNM ENT POINTSVR4O1VR3021451,/.w.:,:?.t?,ail.-.;&:;:,.:ir:1r:it t:,tVR6O1aL203Figure 4vR601 b10LEVEL DIAGRAMFILTER FILTERz.z.(9U(,FJoFREOUENCY : 1 KHZINPUTSELECTOR6Est+(Low) |2.5mV I11TROUBLESHOOTINGSymptomCause and Remedy1 ) Receiver not operative:Pilot lamp does not light.A) Faulty AC power cordReplace the cord.B) Defect in the power switchReplace the switch.C) Broken wire in the power transformerRep lace the transformer.D) Broken power fuseReplace the fuse.2l Fuse blows when power isturned on.A) Power Transformer T851 defectiveReplace the transformer.B) Short in the primary or secondary of the trans-former circuitryRepair the short.C) Damaged rectifier D807Replace the damaged rectifier.D) Short circuit in the rectif ier circuitRepair the short.E) Short circuit in the power transistor TR608a, b orTR609a, bReplace the defective transistor and check circuit.3) Pilot lamp does not light.A) Defective lampReplace lamp.B) Disconnection in the transformer T851 tertiarywindingReplace the transformer.4lPilot lamp lights but no soundfrom both channels.Resistor R814, R809. R923 or R924 openReplace.Capacitor C803, C804, C805, C812, C813, C851,C852, C916 or C917 defectiveReplace the defective capacitor(s).Diode D807 damagedReplace the diode.Open in secondary winding of the power trans-former T851Replace the transformer.Transistor TR804 or TR806 openReplace the transistor(s).Diode D802, D804 or D805 damagedReplace the damaged diode(s).Defective D801 or D803Replace the defective diode(s).A)B)c)D)E)F)G)12SymptomCause and RemedyH) Transistor TR803 defectiveReplace the transistor.l) Defective R802, R803, R804, C801 or C802Replace the defective component(s).J) Defective Relay RL801Replace.5) A Speakers do not work.A) Speaker switch 51 defectiveReplace the switch.6) B Speakers do not work.A) Speaker switch 51 defectiveReplace the switch.7lOne channel does not work withVOLUME at maximum with atest signal applied to the centerterminal of VOLUME controlVR951 of the dead channel.A)B)Defect in transistor TR901, TR902 or TR903 ofTONE AMP BOARD OO43Locate and correct the defect.Defect in transistor TR601, TR602, TR603, TR604,TR605, TR606, TR607, TR6O8, TR609 or TR610of MAIN AMP DRIVER and MAIN AMP BOARD0045Locate and correct the defect.C) Break in copper foil of printed circuit board 6044,0043 or 0045Repair or replace circuit board.Short in speaker output terminalRepair the short.Defective resistor R901, R902, R903, R904, R905,R906, R907, R918, R919, R920, R737, R738,R742, R602, R603, R604, R605, R606, R607,R608, R609, R610, R612, R613, R614, R615,R616, R625, R626, R621 or R622Replace the defective resistor(s).D)E)8) Same as 7 above but channeloperates when test signal isapplied as 7.A) Defective SELECTOR switch 52 or TAPEMONITOR 1 and2 switches 53, 54Repair or replace the switch(es).9) Speaker works normally butheadphones do not work.A) Headphone plug does not mate with jackReplace the plug.B) Defective resistor R651a, bReplace the resistor(s).10) All inputswork normallyexcept for AUX input.Poor contact in AUX input jackRepair or replace the jack.Faulty SELECTOR switch 52Repair or replace the switch.A)B)13SymptomCause and Remedy11) PHONO input not operativeA) Defective 1C501Replace the lC.B) Faulty resistor R501, R502, R503, R504, R505,R506, R507 or R508Replace the faulty resistor(s).C) Faulty capacitor C501, C5O2, C503, C504, C507or C508.Replace the faulty capacitor(s).D) Poor contact in PHONO input jackRepair or replace the jack.E) Faulty SELECTOR switch 52Repair or replace the switch.12) TAPE MONITOR 112notoperativeA) Defective contact in TAPE MONITOR 112 OUTjackRepair or replace the jack.13) FM does not operate.A)Transistor TR808 damaged (open)Replace the transistor.Defective resistor R81 6Replace the resistor.Short circuit in TUNER B+ circuitRepair the short.Poor contact in SELECTOR switch 52Repair or replace the switch.Resistor R301 defectiveReplace the resistor.Choke coil L2O2 defectiveReplace the choke coil.Capacitor C301 defectiveReplace the capacitor.Defective lC 1C201 or lC2O2Replace the defective lC(s).Defective IFT T101 or Coil L203Replace the defective component(s).Defective resistor R201, R203, R204, R205, R216,R217, R218, R221, R222, R225 or R232Replace the defective resistor(s).Defective capacitor C111, C112 or C2O1Replace the defective capacitor(s).Defective transistor TR101 ,TR1O2, TR103 or coil1101-L105 of TUNER BOARD 0042Replace the defective component(s).Faulty lead-inRepair or replace the lead-in.B)c)D)E)F)G)H)t)J)K)L)M)14SymptomCause and Remedy14, Poor multiplex separationA) lmproper adjustmentReadjust T101, VR301 and VR302.(Refer to MPX ALIGNMENT on page g.)B) Transistor TR301, TR302, TR303 or lC 1C301 ofTUNER BOARD OO42 defectiveReplace the defective component(s).C) Variable resistor VR301 or VR302 defectiveReplace the defective variable resistor(s).15) Stereo indicator does not light.A) Defective indicator LED D756Replace the LED.B) lmproper adjustment of VR301 of TUNER BOARDoo42Make readjustment.(Refer to MPX ALIGNMENT on page 9.)C) Defective lC 1C301 or resistor R327Replace the defective component(s).16) FM volume not sufficentA) lf volume of both L and R channels not enough:Front-End defective, or faulty I FT T101 or diodeD2O7, D208 or faulty lC lC2O2,lC301 or capacitorC219 of TUNER BOARD 0042Locate and replace the defective component(s).B) lf sound of one channel not enough: DefectiveLPF301 or TR302 (PCB 0042) in case of L channel,or defective LPF302 or TR303 (PCB 0042) in caseof R channelReplace the defective component(s).17l. AM does not operate.Damaged either 1C401 or TR404 of TUNERBOARD OO42Replace the damaged component(s).Def ective L4O1 , L4O2 or C F401 of TU N E RBOARD OO42Replace the defective component(s).One of resistors of TUNER BOARD 0042 defectiveReplace the defective one.One of capacitors of TUNER BOARD 0042de