3-6
Copyright © 200
9
LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
8. PWM MODULATION PART CHECK
PWM modulation
part check
YES
YES
YES
YES
P7905_PIN9
3.3V checking
Check IC604(PS9829)
VDD PIN voltage(3, 7, 8,
10, 22, 29, 39, 47, 56, 65,
72, 94).
Check X601_PIN2 3.3V.
NO
Refer to
SMPS troubleshooting.
YES
YES
YES
YES
Check IC605_
PIN3 input and PIN2
output.
Check
X601 12.288MHz
operation.
Check IC605_
PIN8 3.3V.
Check IC605_
PIN3 input
Check X601
2.288MHz
NO
NO
IC604
(PS9829) PIN86 CLK
input check
NO
Check FB614
BEAD input, output and
voltage.
NO
Check X601
12.288MHz.
Replace X601.
OK
NO
OK
YES
YES
NO
Replace FB614
NO
Check IC605_
PIN2 output
YES
OK
YES
OK
Replace IC605.
NO
Check R680
(470
Ω
) output.
Replace R680.
NO
Check
IC604(PS9829) DATA
input.
Check each LINE
registor output.
NO
Check IC604
(PS9829) DATA input.
78 PIN->DATA
79 PIN->CLK
Check PWM
modulator output.
FL:75(+)74(-)
FR:71(+)70(-)
NO
NO
Check
DVD ASS`Y(PS9829)
communication
(P7403).
Refer to
CD troubleshooting.
NO
Check
IC100(78KOKF2)
21->PWM_CLK
22->PWM_DATA
43->PWM_REST
output.
NO
YES
YES
OK
YES
OK
Check IC604(PS9829).
OK
Check
LINE registor output.
DATA:R671, CLK:R670
RST:R665
Replace R670, R671
and R665
NO
NO
Replace X601.
OK
YES
YES
YES
YES