LG CM2760 Service Manual page 24

ELECTRICAL TROUBLESHOOTING GUIDE OF AUDIO PART
No VCC 3.3 V
YES
Check IC400 pin4
voltage 5 V.
YES
Check D405 anode
voltage 5 V.
YES
IC401 normal?
YES
Check VCC33 network,
the device a short circuit
will cause no output.
No 12 V
YES
Check Q407 collector
voltage 27 V.
YES
Check Q408 collector
voltage 15 V.
YES
Q408 normal?
YES
Check whether IC301 damage.
NO
Check IC400.
NO
Check Q401.
NO
Replace IC401.
NO
Check Q407.
NO
Check R437 ~ R441.
NO
Check Q407, ZD400.
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