Realistic-STA7-rec-sm 电路图 维修手册.pdf

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1、laLtstrC lSerulce AM /Fwt S Catalog STA-7 TEREO RECEIVER Number:31 -1 968 cusroM MANUFACTURED FoR RADIo sHACK f,n DMSIoN 0F rANDy conpoRAloN RadioFans.CN 收音机爱 好者资料库 (1) (21 (3) (4) (5) (6) PAGE ELECTR ICAL PERFORMANCE SPECIFICATIONS3-4 BLOCKDIAGRAM. -.5 DISASSEMBLY INSTRUCTIONS . ., , .6-7 CIRCUIT O

2、PERATION CHECK . . .8_16 ALIGNMENT INSTRUCTIONS ,. . .17_20 BUILT.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 all units should be able to approximate these - s

3、ome will exceed and some may drop slightly below these 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 -l I r tl ) U z z r G t I d J o U E F t U z f F r = c

4、 a6 ffo o o N G F Jl UI zl z) l II ol rl Jl bl zl 21 t : l . ula (EI IL Y ti J z z - G o F _l JI ul zl zl z t xo =B =1 = N- aF 3E; uc- 3?s o66 otrE oB + siE- =B :g E- o i!*o =F x E-a EO =6 =8 ;E -5- n Writlur ttltr!rr! |ffi ffi, illilillr rilr$tri l l; 1 i ll- I I I 3. DISASSEMBLY INSTRUCTIONS Figur

5、e A 1)To remove chassis from MetalCabinet a) Turn the Cabinet upside down and re- move the six screws from the Cabinet bottom. (Figure A) b) Remove the five screws from the Rear Panel. (Figure B) Figure C1 2) Removal of Front Panel a) Remove the chassis from Metal Cabinet as described in 1). b) Pull

6、 off the Metal Cabinet. c) Remove two screws each from the top and bottom of the Front Panel. (Figure C1, Czl d) Remove the two screws from the back of Front Panel. (Figure D) e) Remove Knobs and pull off Panel. Figure B Flgure C2 -6* Figure D 3)To remove two bottom covers i) Removal of Bottom Cover

7、 Remove the six (A) screws from bottom cover as shown in Figure E. ii) Removal of Bottom Cover E Remove the six (B) screws from bottom cover as shown in Figure E. IA (A) ,l 1* B +(B) ,l a r *t* *r*- (B) ,-(A) Figure E 4)To remove Rear Panel from chassis a) Remove bottom covers as described in 3). b)

8、 Remove the two screws from bottom of Rear Panel. (Figure F) c) Remove the four screws frorn the Rear Panel. (Figure G) Figure F Figure G -7 - START CONNECTION 4. CIRCUIT OPERATION CHECK 1)POWER SUPPLY OPERATION CHECK Connect AC Cord to 120 V AC, 60 Hz (UL, C.S.A.l (24O V AC, 50 Hz for Australian) C

9、heck 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 AMP. OPERATION CHECK Connect 8 O Load to Speaker Output. Connect DC Voltmete

10、rs to Pin No. 3 of MAIN lC 401 (lC4O2) and ground (Plus Supply) and Pin No. 10 and ground (Minus Supply). See Figure 2. MAIN AMP EOARDDC VOLTMETER Figure 2 Check Power Supply Voltage with No lnput (must be r21.2V). Check D501-504, C505, 506. Check for short-circuits. DC Voltage is not i 21.2 V . DC

11、Voltage is r21.2Y. 9.7V ltto a 6 CONNECTION REPAI R -8- CONNECTION NECTION REPAIR Connect 8 o Load to Speaker Output. Check Pop Muting circuit included in MAIN Amp lC 401 about 2-3 seconds after Power is Switched an,. (lC4O2l. U nit activates (1) Check MAIN Amp lC4O1l4O2. (21 Check TR504. Pop Muting

12、 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 position position = 0 dB). (Figure 4) V. T. V. M. at 100 Hz input. (FLAT Figure 4

13、t ;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- CONNECTION REPAIR QI PRE.AMP OPERATION CHECK Set SELECTOR Switch to PHONO

14、. Connect Audio Osc. to PHONO lnPut. connect oscilloscope and VT.V.M to TAPE oUT Jack (see Figure 5) AUDIO OSC. OSCILLOSCOPE SET Figure 5 Equalization Curve response (RIAA Curve)Check for proper PHONO (See Figure 6). I+13.rl Figure 6 20 -3pHgor.r,*, (1) check rR2o1, 2m (rJ;Lf irol. (21 Check C209,C2

15、11,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 at 10 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 next se

16、ction. (3) TONE CONTROL OPERATION CHECK Same Equipment Connection as Figure 3. a 36 U 6 U E t -,o I l- r3.751 -15 t5 to o -to - 10- Proceed to the next section. -11 - Check BASS (F igure 7) Action at TONE COiITROL CURVE . IOOHz + BASS t tO Nxz .+ TREBLE , +lo a ;o z c u -ro c 1 Figure 7 -) AUDTO FiE

17、OUENCY(Hz) Check Bass Control circuit on TONE CONTROL Frequency 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

18、 dB. Frequency Response falls within -+.10 +.2.5 dB. Check LOUDNESS compensation (Figure 8) with Volume set for -30 dB from rated power. +6 3 2 Figure 8 $*ou 1. Check Loudness circuit. 100 lK 10K -IAUOOFREOUENCY(HZ) LOUOTIESSGJRVE Loudness compensation does not fall within +6 r. 2.5 dB at 100 Hz and

19、 +4.5 -1 2.5 dB at 10 kHz. Loudness compensation falls within + 6 r 2.5 dB at 100 Hz and +4.5 i.2.5 dB at 10 kHz. roK P.C.B. REPAI R REPAIR START ADJUSTMENT REPAIR REPAI 3)AM RF/IF OPERATION CHECK Adjust AM lFlRF Alignment. (See AM Alignment Section on page 17,) Set SELECTOR Switch to AM. Connect St

20、andard Loop Antenna to AM SG and radiate signal into the AM Ferrite Antenna L7O1. Connect Oscilloscope, Distortion Meter and V.T.V.M. toTAPE OUT jack on set. (See Figure 9.) AM SG LOOP ANTENNA Figure 9 Check AM coverage: lowest Dial pointer position should be under 520 kHz and highest position shoul

21、d be over 1620 kHz. Readjust AM coverage, (See page 17 for AM Alignment.) 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

22、worse than 500 pV/m. AM Sensitivity is better than 500 pYlm. (Nominal Sensitivity is 200pVlm). L_z_J AM BAR ANTENNA Iteomt L/ SET I l/ f- OSCILLOSCOPE V,T.V,M, DISTORTION I/IETER -12- REPAIR R EPAI R CONNECTION STEP 5 REPAIR Check AM Distortion (lnput level to 5 mV/m). (1) Readjust AM lFlR F Alignme

23、nt. (21 Check AM I F/R F circuit. Distortion is greater than 3.5 %. Distortion is less than 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 / 0.8mm Figure 10 0.8mm 75-85o/o Adjust value of R 150. Signal Meter poi

24、nter does not indicate correctly. Signal Meter pointer indicates correctly. Same equipmentconnection as Figure 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:

25、5mV/m Proceed to next section. -13- CONNECTION REPAIR STEP 2 CONNECTION 4) FM RF, IF stretch or squeeze) Adjust for maximum reading on AC Volt- meter. I Same as above106 MHz106 MHz Tune to Signal TC101 (FM ANT Trimmer) TCl02 (FM RF Trimmer) 10Repeat STEPs (8) and (9) until no further improvement is

26、noticed. 11 Same as STEP (8) ANT. input: 1 mV 98 MHz98 MHz Tune to Signal T110Adjust for maximum reading on the Receivers meter, 12 Same as STEP (8) ANT. input: 100m VR 101Adjust so the Meter Pointer on Receiver is 90-95% of full scale. -18- FM ALIGNMENT SET-UP 3OOO DUMMY FM ANT Sweep Gen. Figure 15

27、 FM STEREO ALIGNMENT Equipment Required 1. Stereo Modulator 2. FM Signal Generator . . 3. AC Voltmeter 4. Oscilloscope 5. D istortion Meter 6. Frequency Counter Note: See P.C.B. illustration for alignment/test points. Preliminaries Set SELECTOR switch to FM STEREO. TAPE OUT L or R) AC V.T.V.M. DISTO

28、RTION METER generator. i rP1 l.i_- atR144 7 Al Figure 16 Connect Stereo Modulator to EXT. Mod. terminal on FM signal Modulation Level of 19 kHz Pilot Signal .8-10% Output Level . 1 mV Frequency . Approximately 98 MHz Deviation 75 kHz 1OO7o modulation of composite signal FM SIGNAL GENEBATOR SCOPE PAT

29、TERN MULTIPLEX l$ffi54ffi1;. ! e4- ffiffi. d ffiffiffiffi1 e$ffi iit*si %si TF2O3 2SC923(EU) c2l6 R222 0.22125 tK rR 202 I I aTth I RrTo I rR ZO4 ?5(900 t-g/-!-4J 25C923(LU) iGut - . ) : i= c2r0 c212 o.oo33 0 ol TRr07 25C930 (D,E) TR 108 2SC930 ID,E) 0107, r08 or l5l06FM R13 8 eavlK or07 Rr4o ct4r R

30、t42 _L:a_, rN60P x r00P r0fi R I77 LPFl01 !.13?(9 ct78 Rr76 o.2az5 rh IRll3 25C900 (E.U)d2*23GEn IR II4 25Ca00 (E,U)d2SAS(E_F) + c171 330/16 Rr80 I 3.3K 1 CrSO T 0.0082 I * c923(EU) MEIER 4.5 rR304 2SC90OE.U) or 2S2309(E,F) OHM. TED lN 11F lP = 10-6pF), SSIS GROUND WITH A VOLTMETER (10 KO/V). ) COND

31、ITIONS: Wl.rH NO INPUT AND AT 10W (1 kHzI OUTPUT POWER (lNSlDE PARENTHESIS). lT FOR OPTIMUM PERFORMANCE (Refer to VALUE SELECTED PARTS section). HEAD PHONE JAC K I I 142 -PL7O1 METER LAMP PL 705 o505 SRIK c102 u50 B-L iJ c I AUX I I ED lN OHM (K= 103 OHM, M = 106 050r - 050( 5K-l( 2 ac r20v 60Hz UL

32、E !l- oY9 +: a * c162 4.11/SO 9: I ?A r ti 3 6543 lc l0l LA 33sOO cr6e qr Y 069 tpt )aiR69 r 8x R19l c189 17 22aA6 Rt51 -r -T -dr R411 6.8x cr1 0-1 I :*: Rl2 3 t.2 M lc3?l I 25P !r t5v - tk a 9 -43- 2I.EXPLODED VIEW xa 6;l -,1 ! .-r RJ / - , 7-1( ;. -_-/ (j - ,. r; ,l. .r,Ul- A i u - -fr16A $*-YY)-

33、-J il RADro sHAcK EI DrvrsroN oF rANDy coRpoRAroN U.S.A.: FORT WORTH, TEXAS 76102 CANADA: BARRIE, ONTARIO L4M 4W5 AUSTRALIA TANDY CORPORATION BELGIUMUK 280 316 VTCT0RTA R0A0 RYDALMERE, NSW 2116 PABC INDUSTRIEL OE NANINNE 5140 NANINNE BILSTON ROAO, WEDNESBURY WEST MIILANIS WS1O 7JN -l I I i 1 ; I 1 -? 9A8Printed in Japan