Dell UltraSharp 2208WFP, Service Manual

Page: 39 / 63

Service Manual
38
4.Power (include IF +5Vand +3.3V) supply normal ,key function
OK,but backlight can’t be turned on
LED lamp is OK
No backlight
Yes
Yes
Is there 27V Voltage on
Pin 7,8 & 13,14 of T1
Yes
Is there PWM signal on
Pin13 of U1
Yes
Is there High level voltage
on Pin16 of U1
Yes
Vsense voltage is 2.9V
No
Are there PWM signal on
pint on Pin12 of U1
Yes
Pin14 of U1 Voltage
is Low Level
Pin6&10 of U1 voltage is
high level voltage
No power supply to
inverter
No
Yes
Check the cable that from I/F
BD to P/I BD is ok
No
Q6, Q7
fail
Yes
Check power supply
N
o
Replace Q6, Q7
Check I/F BD
No
Check I/F BD
No
Lamp connector opened
Yes
U1 Failure
No
Feedback circuit failure
Yes
Check R21,R22,C10
Yes
U1 protected
Yes
Check ZD1, R1 , ZD2, R2, C12, C13
Yes
END
Yes