21
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.]
Does “H” output in IC401
pin ?
Check and replace R705,
R706, Q701 and LED701
(LED703 for DELL).
Is the CLOCK Frequency of
IC401 pin 16.93MHz?
Check the power input
pattern.
Check IC401.
Check and replace
X501; 33.86MHz,
X502: 40MHz
Is the CLOCK Frequency
of IC501 pin 16.93MHz?
Check and replace R407,
C530, R444.
YES
OK
NG
YES
YES
NO
NO
NO
12
35
68
A-1
A-1
