LG CRD-8402B Service Manual page 5

3. Troubleshooting Guide
A. LED doesn't light.
Check Power Voltage
(TP1:3.3V, TP2:12V, TP20:2.7V)
Reference Voltage
[TP3:DVC(1.4V) and GND.]
OK
Does "H" output in IC401
pin ?
12
YES
Check and replace R705,
R706, Q701 and LED701
(LED703 for DELL).
A-1
Is the CLOCK Frequency
of IC501 pin 16.93MHz?
68
YES
Check and replace R407,
C530, R444.
NG
Check the power input
pattern.
NO
Is the CLOCK Frequency of
IC401 pin 16.93MHz?
35
YES
Check IC401.
Check and replace
NO
X501; 33.86MHz,
X502: 40MHz
NO
A-1
21