LG OM7550 Service Manual

3-27
ELECTRICAL TROUBLESHOOTING GUIDE
No AMP output
Check PFC P.CTL from μ-com.
Check AMP P.CTL from μ-com.
Replace D908, Q955, PC903.
Replace D908, Q956, PC902.Replace F911.
Check or replace
IC904, Q907~Q910.
Check or replace IC902 and
Check Q905~Q906 gate(pin1)
Components (Resistors, Diodes).
Is Q905~Q906 OK?
Replace Q905~Q906.
Check or replace D954~D955.
Check line of MAIN PCB is
short or not.
Is the
C904 Voltage
about 390 V?
Is F911 normal?
Is the
PFC P.CTL OK?
Is the
AMP P.CTL OK?
Is the
VCC 12 V supplied to
IC904 pin16?
Is the
VCC 12 V supplied to
IC902 pin8?
NO
YES
NO
NO
NO
NO
YES
NO
YES
YES
YES
YES
NO
NO

LG OM7550 Specifications

General

Brand	LG
Model	OM7550
Category	Stereo System
Language	English