United-Motors-Service-Delco-985264 电路原理图.pdf

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1、23 收音机爱 好者资料库 RadioFans.CN 10.8 V. LINE GOOD SIGNAL VOLUME R-23, MOST-OFTEN-NEEDED 1963 RADIO SERVICING INFORMATION DELCO RADIO BUICK Model 980296 CHEVROLET Model 985264 PONTIAC Models 983579, 983687 STUDEBAKER Models AC-3216, AC-3247, AC-3256 (Continued from page 23. Applicable alignment table is o

2、n page 26, under another model.) I. TROUBLESHOOTING PROCEDURE 1. Turn radio on (ear near speaker). If no “thump” is heard, suspect: open fuse, open “Fuse resistor,” loose speaker plug, open speaker, or shorted DS501 transistor. 2. Isolate trouble to a stage (AF, IF, Conv., RFsee letters on circuit b

3、oard below). Use a noise generator or other device at each point, starting with 1. 3. Measure voltages in defective stage. Note: Voltage between 10.8 V. line (conductor #2) & emitter (E) of each stage checks conduction of that stage. II. VOLTAGE AND TROUBLE HINTS CIRCUIT BOARD CO (COMPONENT VIEW)N q

4、 TUNER 1 T j -. -SB 7l 95 ULfcJLLP V YELLOW LEAD OB BARE ERMINAL -EMITTER Stage Voltage (B, C, E, to ground) Bias Voltage (B to E) Defect Quick Check to Confirm Normal Over .5 V. Open small transistor Bridge good one across old one Normal Normal Open capacitor Bridge good one across old one E is zer

5、o Wrong polarity Shorted emitter cap. Ohmmeter C is 11 V. Normal Open collector circuit Ohmmeter E is very low. “0” or reversed Oper emitter circuit Ohmmeter Normal Normal Defective IF Ohmmeter & try for peak. LOCATING LUG GREEN LEAD DR BARE TERM NAL -BASE MTG STUD COLLECTOR DS 501 Transistor Termin

6、als NOTE: Mtg. insulators, #1221642, not packaged with DS-501. These insulators are not required if rad iator is insulated from case. * Small transistors may be checked for open by bridging a good one across (without unsoldering old one). All three leads must be firmly connected. If radio starts pla

7、ying, replace old one. INJECT AT ANT. SOCKET (CHECK ANT. CIRCUIT) LOUDER SIGNAL (CHECKS A F. STAGE) WEAK SIGNAL (CHECKS OUTPUT) LOUD SIGNAL (CHECKS I.F.STAGE) LOUDER SIGNAL (CHECKS CONV. STAGE) DS 22, 24, 25 and 26 Transistor Terminals ABOUT SAME OR SLIGHTLY WEAKER (CHECK R.F. STAGE) GOOD SIGNAL DS-24 WEAK OR NO SIGNAL I CIRCUIT BOARD (PRINTED VIEW) NUMBERS IN SQUARES ARE MAJOR TEST POINTS FOR STAGE ISOLATIONINJECT SIGNAL 24 收音机爱 好者资料库 RadioFans.CN