Check The Inverter Board Circuit - NEC MultiSync LCD1550ME Service Manual

13. Check the inverter board circuit

Check Vin pin is around 15.5V.
On/Off pin is over 2V.
Brightness pin is between 0.3V and 3.0V.
Check IC pin 3 around 5V.
Check CN2 and CN3 is connected right.
Check the IC pin 3 is PWM.
Check the buck circuit.
NG
OK
NG
OK
NG
OK
NG
OK
OK
OK
OK
NG
OK
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It is not inverter problem.
Check Q1, Q2, Q8, D1, F1 and repair them.
Check one of these components was short
to GND.
Check CCFL and repair them.
Check the IC pin 11 is triangle.
Check D2, C14, R11and repair them.
Check the IC pin 9 is 2.5V.
Check R20 and R28 and repair them.
Check the IC pin 8 feedback waveform.
Check CR1, CR2 and repair them.
Repair the LM339.
Check the Q4, Q10, R5, D5, L1
and repair them.
6-18
NG
NG
NG