
49
ViewSonic Corporation
Confidential - Do Not Copy
VX2255wmh-4
VX2255wmb-4
Backlight can’t be turned on
Yes
No
Yes
No power supply
Inverter
Check the cable that from
I/F BD to P/I BD is OK
Is there 16V voltage on
pin3.4 of T501.T502
Yes
U501, U502 Fail
No
No
Check power
supply
Yes
Replace U501, U502
Is there PWM signal on
pin4 of IC501
Yes
No
Check I/F BD
Is there High leve voltage
on pin10 of IC 501
Yes
No
Check I/F BD
Vsense voltage is 2.9V
Yes
Yes
Lamp connector opened
Are there PWM signal on
pin1, pin15 of IC501
No
No
IC501 Failure
Pin 5 of IC501 voltage is
Low level
Yes
Yes
Feedback circuit
failure
Yes
Check C524, R528,
R533, D507
Led lamp is OK
No backlight
No
Pin3 of IC501 voltage is
high level voltage
Yes
IC501 protected
Yes
Check D505, D511, D512,
D513, R520, C520
End
Yes
Downloaded from
www.Manualslib.com
manuals search engine