Optima L903A, Service Manual, Page: 39 / 54

19" Wide LCD Color Monitor Optima L903A
39
2. W/LED No Backlight
Check C811 (+) =12V
Check the resonant wave of Pin7 & Pin8 for PT801/PT802
Check the Pin1, Pin15 of IC801 have square wave
Check the output of PT801/PT802
Check ON/OFF signal
Check IC801 PIN2=5V
Check adapter circuit
Check Interface board
OK
OK NG
NG
Check Q801,Q802,Q803
NG
NG OK
Check Q805,Q806 have the output of
square wave at short time.
Check IC801
Check Q805,Q806,PT801,PT802
Check C816, C841 or C834, C837
OK
OK
OK
NG
NG
Change PT801 or PT802
Check connecter & lamp