Check Cn902 Pin4, 5 = 5V - BenQ E2220HD Service Manual

21.5" LCD Color Monitor
Power Board
(1). No power

Check CN902 PIN4, 5 = 5V

Check AC line volt 110V or 220V
Check the voltage of C905 (+)
Check start voltage for the pin8 of U901
Check the auxiliary voltage is bigger than
10V and smaller than 20V
Check U901 pin5 PWM wave
Check U903/U904/D903/ZD921/ZD922/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 U901
1) Check U901
2) Check R909/D901/C907 circuit
Check U901
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BenQ E2220HD