United-Motors-Service-Delco-981968 电路原理图.pdf

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1、VOLUME R-19, MOST-OFTEN-NEEDED 1959 RADIO SERVICING INFORMATION BUICK MODEL 981968 (Additional material on the next page adjacent at right) I2AD6 OSC.-MOD. I2DS7 DET.-AUD. I (I8)F -H X1 L K 1.B I-01 Q B i.rr.1 WEG. 251 53 00OTD4T BEFORE MEASURING TRANSISTOR VOLTAGES, THE SHORTING TYPE SPEAKER SOCKET

2、 MUST BE OPENED AND A 4 OHM SPEAKER CONNECT ED. IF TRANSISTOR IS REPLACED, ADJUST BIAS POTENTIOMETER (ILLUS. 73 ) TO OBTAIN PROPER COLLECTOR VOLTAGE WITH 12 VOLTS INPUT TO RADIO. ; + -ILLUS. 59 IS A FUSE RESISTOR FOR THE TRANSISTOR 350 DS50I 7t OUTPUT 750 m .00022k) 77 I BASIC TROUBLESHOOTING PROCED

3、URE 1. Put ear next to speaker and turn radio on. If slight “thump” is heard as this is done, trouble is m tube stagestry new tubes. YELLOW LEAD OR BARE TERMINAL* -EMITTER LOCATING LUG GREEN LEAD OR - BARE TERMINAL -BASE . MTG. STUD OOLLECTOR DS 501Transistor Terminals 2. If no “thump” at all is hea

4、rd, measure voltage from transistor case to radio chassis. If 1-2 volts is present, transis tor is operating normally and trouble is either in speaker, speaker interlock socket, or one of the tube circuits. 3. If no voltage is present in step 2, check transistor circuit and particularly the transist

5、or fuse resistor, Illustration No. 59. This resistor is mounted between points 32 and 26 on circuit board and should measure less than 1 ohm. 2uIoTlrvTRANSF0RMER WILL APPEAR SHORTED IF SHORTING TYPE SPEAKER SWITCH IS NOT OPENEO. ESCUTCHEON CROSS SECTION 收音机爱 好者资料库 RadioFans.CN PARTS LAYOUTCHASSIS VIEW _ PART LAYOUTTUBE VIEW 19 收音机爱 好者资料库 RadioFans.CN