LG CM9750 - Page 46

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 Q911 ~ Q914 gate(pin2)
Components (Resistors, Diodes).
Q911 ~ Q914 OK?
Replace Q911 ~ Q914.
Check or replace D953 ~ D956.
Check line of MAIN PCB is short or not.
Is the
C903, C913 Voltage
about 395 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