Realistic-STA85-rec-sm 电路图 维修手册.pdf

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1、ruLrstC. Seruice STA.85 AM /FM STEREO RECEIVER Catalog Number:31 -2061 cusloM MANUFACIURED FoB RADIo sHACK|R orvrstoN 0F rANDy conponAloN RadioFans.CN 收音机爱 好者资料库 CONTENTS SPECIFICATIONS 3 all units should be able to approximate these-some will exceed and some may drop slightly below these specs. Lim

2、it 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 BLOCK DIAGRAM ; o = E PH i E-.dr = E9 t-Jt A E E:; *E E ee H:= =3 _l E al-=*= =: ll 5 I ; I+ tt = t.Ftt = 3 3; = = = z = LA- E-, -: : -.,

3、 : = =e =I =r t Er -3 t =: =F -= E 3- t= AF =F t El = Es at = t- _- = ts= o I =,s 9l t6 _ ,*l l l _l I F zq; 6 t- o=3 3! ,9 = =-r- I I I _l_ 1 i; = .l i l-r t = =q o- Eo -r I I E E I I r = t =l !l _l _J pilot lamp does not light. A) Faulty AC power cord Replace the cord. B) Defect in the power switc

4、h Replace the switch. C) Broken wire in the power transformer. Replace the transformer. D) Broken power fuse Replace the fuse. 2l Fuse blows when power is turned on.A) Power Transformer T851 defective Replace the transformer. B) Short in the primary or secondary of the transformer circuitry Repair t

5、he short. C) Damaged rectifier D801 Replace the rectifier. D) Short-circuit in the rectifier circuit Repair the short. E) Short circuit in power transistor TR609a, b or TR610a, b Replace the defective transistor and check circuit. 3) Pilot lamp does not light.A) Defective lamp(s) Replace lamp(s). B)

6、 Open in the transformer T851 tertiary winding Replace the transformer. 4) Pilot lamp lights but no sound from either channel. A) Resistor R801, R807, R508, R509, R904 0r R915 open Replace. B) Capacitor C507, C508, C801, C802, C807 or C808 defective Rep lace the defective capacitor(s). C) Diode D801

7、 damaged Replace the diode. D) Open in secondary winding of the power trans- former T851 Rep lace the transformer. 5) A Speakers do not work.A) Speaker switch SW8 defective Replace the switch. 6) B Speakers do not work.A) Speaker switch SW8 defective Replace the switch. 12 SYMPTOMCAUSE AND REMEDY 7l

8、 One channel does not work with VOLUME at maximum, with a test signal applied to the center terminal of VOLUME control (VR551 or VR552) of the dead channel. A) Defect in transistor TR901, TR902 or TR903 of Audio Amp Board 6053 Locate and correct the defect. B) Defect in transistor TR601-TR610 of Aud

9、io Amp Board 6053 Locate and correct the defect. C) Break in copper foil of printed circuit board 6053 Repair or replace circuit board. D) Short in speaker output terminal Repair the short. E) Defective resistor R903, R904, R906, R907, R914, R915, R603-R606, R609, R610, R615, R620-R627 Replace the d

10、efective resistor(s). 8) Same as 7 above but channel operates when test signal is applied as 7. A) Defective lC 1C501 Replace the lC. B) Faulty resistor R503, R504, R508 or R509 Replace the faulty resistor(s). C) Faulty capacitor C501 or C506 Replace the faulty capacitor(s). D) Defective selector sw

11、itch SW1 Repair or replace the switch. 9) Speaker works normally but head- phones do not work. A) Headphone plug does not mate with jack Replace the plug. B) Defective resistor R629a, b Replace the resistor. 10) All inputs work normally except AUX input. A) Poor contact in AUX input jack Repair or r

12、eplace the jack. B) Poor contact in selector switch SW1 Repair or replace the switch. 1 1) PHONO input not operative.A) Poor contact in PHONO input jack Repair or replace the jack. B) Faulty selector switch SW1 Repair or replace the switch. C) Defective lC 1C501 Replace the lC. 12l, TAPE OUT not ope

13、rative.A) Defective contact in TAPE OUT jack Repair or replace the jack. 13 SYMPTOMCAUSE AND REMEDY 13) FM does not operate.A)Defective resistor R 107, R114, R207, R316, R317 or R235. Replace the defective resistor(s). Short circuit in Tuner B+ circuit Repair the short. Poor contact in selector swit

14、ch SW1 Repair or replace the switch. Defective diode D201 Replace the diode. Capacitor C301 defective Replace the capacitor. Defective transistor TR201 or lC 1C201 Replace the defective component. Defective IFT T201 Replace the lFT. Defective capacitor C2 1 1 Replace the capacitor. Defective transis

15、tor TR 101, TR 102, TR 103 or Coil L101, L1O2, Ll03 of Tuner Board 0055 Replace the defective component(s). Faulty lead-in Repair or replace the lead-in. B c) D) E) F) G) H) t) J) 14l Poor multiplex separationA) lmproper adjustment Readjust T2O1, VR301 and VR302. (Refer to MPX ALIGNMENT on page 9) B

16、) Defective lC 1C301 Replace the lC. C) Variable resistor VR301 or VR302 defective. Replace the variable resistor(s). 15) Stereo indicator does not light.A) Defective LED D303 Replace the LED. B) Defective lC 1C301 or resistor R322 of Tuner board 0055 Replace the defective component(s) . C) Defectiv

17、e diode D301 Replace the diode. 16) FM volume not sufficient.A) lf volume of both L and R channels not enough Front End defective, or faulty transistor TR201 lC 1C201, IFT T201 or diode D2O3, capacitor C211 or faulty TR301, TR302, tC301 or C301 of Tuner Board 0055 Replace the defective component(s).

18、 B) lf sound of one channel not enough: Defective L301 in case of L channel, or defective L302 in case of R channel Replace the defective coil. 14 SYMPTOMCAUSE AND REMEDY 17l AM does not operate. Damaged 1C401 of Tuner Board 0055 Replace 1C401. Defective L4O1, L404, T401 or T4O2 of Tuner Board 0055

19、Replace the defective component(s). Defective diode D401 or D4O2 of Tuner Board 0055 Replace the defective diode(s). One of resistors of Tuner Board 0055 Replace the defective part. One of capacitors of Tuner Board 0055 Replace the defective part. Selector switch SW1 defective Repair or replace the

20、switch. Defective Tuning Gang Replace Tuning Gang. Damaged AM bar antenna Repair or replace the bar antenna. A) B) c) D) E) F) G) H) 18) LOUDNESS has no effect.A) Defective LOUDNESS Switch SWs Replace the switch. B) Defective C701 or R703 Replace defective component(s). C) Defective VOLUME control V

21、R551 or VR552 Replace. 19) STEREO-MONO not effectiveA) Defective MONO switch SW4 Replace the switch. 2Ol TAPE MONITOR noteffectiveA) Defective TAPE MON switch SW3 Replace the switch. B) Poor contact in TAPE lN input jacks Repair or replace jack. C) Resistor R702 defective Replace the resistor. 21!.

22、BASS control has no effect.A) VR902 defective Replace. B) Defective C908, C909 or R908, R910, R912 of Audio Amp Board 6053. Replace the defective component(s). 221 TREBLE control has no effect.A) VR901 defective Replace. B) Defective C906, C907, R909, R91 1, R913 of Audio Amp Board 6053 Replace the

23、defective component(s). 23t. Excessive noise with PHONO inputA) B) Faulty lC 1C501 Replace the lC. Faulty R501, R503, R504 or C501, C506 Replace the faulty component(s). 15 SYMPTOMCAUSE AND REMEDY 24l, Noisy VOLUME controlA) Defective VR551 or VR552 Replace the variable resistor. B) Defective capaci

24、tor C506, C901, C905 or C912 Replace the defective capacitor(s). 25l. SIGNAL meter not functioning.A) Defective meter Replace the meter. B) ln case of FM reception, lC2O1, D2O4 or TH201 defective Replace the defective component(s). C) ln case of AM reception, 1C401 or VR401 defective Replace the def

25、ective component(s). 26l, AUTO-MAGIC AFC has no effect when AUTO-M switch is ON. (White light behind the tuning meter does not change to red when the tuning control is touched.) A) Transistor TR701 ,TR7O2 or lC 1C701 defective Replace the defective component(s). B) Resistor R706, R715, R716 or R718

26、defective Replace the defective resistor(s). C) Diode D7O1, D7O2 or D852 defective Replace the defective diode(s). D) Capacitor C7O4 or C705 defective Replace the defective capacitor(s). E) Defective switch SW2. Replace the switch. 271 Red light does not light when the tuning control is released. A)

27、 Defective transistor TR701 (open) or TR702 (short) Replace the defective transistor(s). 281 Hl-FlL has no effect.A) Defective switch SW6 Replace the switch. B) Defective capacitor C702 Replace the capacitor. NOTE: Transistors TR605 and TR606 protect the audio output stage when abnormally high curre

28、nt flows through TR609 and TR610, caused by excessive drive at input, or too low impedance load is connected at output. lf increase of the current is excessive, the voltage across R623 and R626 will turn on TR605 and TR606 which are normally not biased on. The collector potential of these transistor

29、s (through D601 and D602 diodes) reduce bias on TR607 and TR608, which causes output transistor current (TR609 and TR610) to reduce. This performs two safety functions. 1. Protects the output circuit devices. 2. Protects the speakers from loud clicks, pops and excessive levels. TO OBIVT CIBCUIT TO O

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41、 i =+ l+ :+ 6) . -.:_. f-E -:Ex:-r:_ -:-r st tri *l s.r *l , _ I C907a _oY nT-! E nJ dJ El a* r L v,eo, , .-1+ Slf fi v,so2 l-sg *i n E| E E i azop aR j iiEli I -_- I . . .- _F POWER,/SPEAKERS 20 TREBLE SEMICONDUCTOR LEAD IDENTIFICATIONS ELECTRICAL PARTS LIST CAPACITORS Ref. No. Value (F) Voltage (v

42、) Toler- ance %t Material c 101 cl02 cl 03 c 104 c 105 c1 06 c1 07 c 108 cl 09 c111 c112 c113 c114 c1 15 c1r6 cl17 cl 18 c1r9 c121 c201 c202 c203 c204 c205 c206 c207 C2OB c209 c210 c211 c212 c213 c214 c215 c216 c217 c2r8 c219 1BP 22P 0.02tt 18P 0.51 P 10P 1 00P 0.01p 0.02p 0.02p 24P 0.51 P 4P 10P 33

43、P 15P 0.02p 0.02p 0.04p 0.01p 0.04p 1 000P 0.01p 10P 0.04p 0.04rr 0.04p 1 00P 0.47 p 22tt 0.04p o.1p 3.3r, 0.47 p 1p 0.47 p 0.04p 0.04p 50 50 25 50 50 50 50 25 25 25 50 50 50 50 50 50 25 25 25 25 25 50 50 50 25 25 25 50 50 16 25 50 25 50 50 50 25 25 110 110 110 110 t5 15 tl0 t10 tl0 tl0 t5 t5 tl0 t5

44、 t10 t5 tl0 tl0 tl0 t10 tl0 tl0 t10 t5 tl0 tl0 t10 i1O +75 -10 +5O -10 tl0 +75 -10 +75 -lo +75 -10 +75 -10 +75 -10 t10 tl0 Ceramic Ceramic Ceramic Ceramic Ceramic Ceramic Ceramic Ceramic Ceramic Ce ram ic Ceramic Ceramic Ceramic Ceramic Ceramic Ceramic Ceramic Ceramic Ceramic Ceramic Ceramic Ceramic

45、 Ceramic Ceramic Ceramic Ceramic Ceramic Ceramic Electrolytic Electrolytic Ceramic Electrolytic Electrolytic Electrolytic Electrolytic Electrolytic Ceramic Ceramic Ref. No. Value (F) Voltage (v) Toler- ance (/l Material c220 c221 c222 c223 c224 c225 c226 c227 c237 c301 c302 c303 c304 c305 c306 c307

46、c308 c30g c310 c31 1 c312 c3 13 c314 c31 5 c316 c3r7 c31B c319 c320 c321 c322 c323 c324 c325 c326 c327 c401 c402 c403 lop 0.04p 0.04p 0.04p 4.7 p 33p 0.02p 0.04p 33 4.7 p 0.33p 0.33rr 3300P 3300P 1 800P 0.047 p 1 500P 0.22p 0.47 p 0.22p 1 800P 1 800P 6800P 6800P Not Used Not Used 1 B()OP 1 800P 0.1!

47、, 0.1p 18P 18P lpt lp 390P 390P 0.01p 0.01p 10p 16 25 25 25 25 16 25 25 16 25 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 50 25 25 r6 +75 -10 +75 -10 +75 -10 t10 t10 t10 t10 tl0 +75 -10 +75 -10 +75 -10 ti0 tl0 tl0 tl0 +s0 -lo t10 t10 110 +75 -lo +5O -20 t10 t10 +50 -10 110 t

48、10 +75 -10 +75 -10 tl0 tl0 +75 -10 +75 -10 tl0 tl0 110 t10 +50 -10 Electrolytic Ceramic Ceramic Ceramic Electrolytic Electrolytic Ceramic Ceramic Electrolytic Electrolytic Electrolytic Electrolytic Polyester Polyester Ceramic Polyester Polyestyrene Electrolytic Electrolytic Electrolytic Ceramic Ceramic Ceramic Ceramic Polyester Polyester Electrolytic Electrolytic Ceramic Ceramic Electrolytic Electrolytic Ceramic Ceramic Ceramic