LG OK99 Service Manual page 57

ELECTRICAL TROUBLESHOOTING GUIDE
NO AUDIO CHECK
B
Pin47, 48,
49, 50 of IC601,FL/FR±
signal OK?
YES
IC602
FL/FR audio signal
OK?
YES
Pin13 of
IC700, IC701 FL/FR audio
signal OK?
YES
±66 V, -B+12V, ±5 V
power voltage OK?
YES
Q705,
Q706, Q707, Q708
OK?
YES
Q705, Q706, Q707, Q708.
NO
Check IC601.
NO
Check IC601, IC602.
NO
Check IC700, IC701.
NO
Check SMPS.
NO
Check
Check speaker cable connection.
NO
Check IC601.
NO
Check IC601, IC603.
NO
Check IC702, IC703.
NO
Check SMPS.
NO
Check
Q714, Q715, Q701, Q702.
OK
3-32
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Pin45, 46 of IC601,
SW+/- signal OK?
YES
IC603 SW+/-
audio signal OK?
YES
Pin13 of
IC702, IC703 SW+/- audio
signal OK?
YES
±66 V, -B+12V, ±5 V
power voltage OK?
YES
Q714,
Q715, Q701, Q702
OK?
YES
Only for training and service purposes.