Trouble Sh ooting
Page 5
A LC502
3. Checking the back light unit
Is +15V supplied to P803
pin 3, 4 to inverter PWB?
OK
NG
Failure point
Inverter cable disconnection.
Check the INV_EN signal of the rectangle input I307 pin 5 at TTL high level
OK
NG
Is a "H" level being output in the TTL level from I300 pin 143
Or, is INV_EN signal of the rectangle being output?
NG
Failure point
Printed wire broke between
I300 pin 143 and I307 pin 5
Check the PWM signal of the input from I303 pin 7 is a BRI signal
OK
NG
Failure point
1) Printed wire broke between
I303 pin 17 and I307 pin 3
2) I307 failure.
Failure point
1) Inverter cable disconnection.
2) Inverter of LCD module failure.
