Backlight Can - Dell 2209WA Service Manual

Service Manual
4.Power (include IF +5Vand +3.3V) supply normal ,key function
OK,but backlight can't be turned on
Backlight cannot be turned on,is the
on-off control signal come from IF ok?
Yes Is the on-off control signal #109 of U105
Yes
high-low convertible when DC on/off
Is the
NO Check
voltage
T850 or
16V at T1
F850
PIN4?
Yes
Check U1
pin6 Voltage
is 5V
Yes
Check U1 pin1 NO Check
Voltage is Q3
lower
YES
Check T1 pin7 and pin10 Open or
Short
Yes
Change T1
47
NO
NO
Change U105