BenQ M2400HD Service Manual page 52

24" LCD Color Monitor
Power Board
No power
Check CN902 PIN5.6 = 5V
Check AC line volt 110V or 220V
Check the voltage of C905 (+)
Check start voltage for the pin8 of IC901
Check the auxiliary voltage is bigger than
10V and smaller than 20V
Check IC901 pin5 PWM wave
Check D908/D906/D907/ZD921/ZD922/Q903/ZD902
NG
OK
NG
OK NG
NG
OK
NG
OK
OK NG
Check AC input
Check bridge rectified circuit and F901 circuit
Check R904, R905, Change IC901
1) Check IC901
2) Check R909/D901/C908 circuit
Check IC901
52
BenQ M2400HD