LG OK99 Service Manual page 50

ELECTRICAL TROUBLESHOOTING GUIDE
POWER SUPPLY ON SMPS BOARD
No -5 V
Is the
VCC -7 VA supplied to IC953
pin2?
YES
Is there
'H' signal at Q953
Base?
YES
Check or replace Q953, Q957.
Or check line of MAIN PCB is
short or not.
No output AMP gate line
Is the VCC
13 VA supplied to IC952
pin1 to pin3?
YES
Check and replace IC952.
Or check line of MAIN PCB is
short or not.
NO
Is the D967 normal?
Check or replace Q951.
NO
Check VFD_PWR_CTRL
From DSP(IC501_C1).
NO
Is the
R9C7, R938 normal ?
Check or replace D952, D959.
3-25
NO
YES
NO
YES
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Check or replace D967.
Check or replace R9C7, R938.
Only for training and service purposes.