Power Amp Part Check - LG CK57 Service Manual

ELECTRICAL TROUBLESHOOTING GUIDE

6. POWER AMP PART CHECK

POWER AMP PART CHECK
Check
CN102 Pin13, 14: +12 VA
Pin5, 6, 7 : 49 V.
Check IC701, IC702
Pin25, 26, 38 , 39, 42, 43, 50, 51, 55, 56, 64
input voltage.
Check IC701, IC702
Pin64: +12 V input.
Check PWM Modulator input
IC701 Pin4, 5 / IC702 Pin4, 5. 10, 11.
Check PWM modulator output
IC701/IC702 : pin28, 29, 36, 37, 44, 45, 52, 53.
Check output
line coil (L705, 706, 707, 708).
OK
YES
YES
YES
YES
YES
YES
YES
NO
Refer to SMPS troubleshooting.
Check IC106 for +12 V.
NO
Check each line resistor output voltage.
NO
3-22
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Replace the coil.
Only for training and service purposes.