LG PF-43A20 Service Manual page 24

NO RASTER
Is the voltage at
Pin 3 of IC501 9V?
Does the square
waveform from pin 4 of
IC501 appear?
No
Check/Replace
IC501
Is the waveform at
collector of Q401 normal?
No
Check/Replace
Q401, T401,
R416, R417
Is the waveform of collector
of Q402 normal?
No
Check/Replace
Q402
Check/Replace
Check +B voltage
at R406.
Normal
No
Check 5V, 9V,
Yes
12V lines
Yes
Check I
Yes
Bus lines
(SDA, SCL)
Yes
Yes
T401
0V
Check F801A
OK
Check the voltage
of C809(+)
2 C
200~ 380V
Check the voltage
at pin 9 of IC825
6~ 8V
Check/Replace IC887,
D825, D826 Check the
secondary voltage are
shorted
- 24 -
Open
Check/Replace
F801A, D821, IC825
0V
Check/Replace
D821
Lower than 6V
Check/Replace
D801, D802,
D807, ZD801,
Q801, IC825