820-00165-a no backligt

[turbo]

this board had slight water damage, board turns on no back light ( there is image , i changed the led driver, 2 times, feed back line is good (A5) , it have 8.59v on back line line,
known good screen,

i notice EDP_BKLT_PWM 0v

R7731=2.8v

any idea

 

[JohnB8812]

What voltage do you have on BKLT_EN? This sounds like an issue with LED Driver soldering or possibly feedback line on the front side of the board.

 

[2informaticos]

Do PRAM reset few times.
If no result, remove R7704 and run a wire from R7715 to C7704.
Let see if backlight appears.

 

[turbo]

I did that remove r7704 and and run wire from r7715 to caps still no back light

third time i changed the drive now a5 feed back pin burn out

 

[2informaticos]

Be sure to have good continuity for FB line; check XW7720 integrity.
However, BKLT_PWM signal should have some voltage before.
You didn't post its value after modded.

 

[turbo]

finally fixed, feed back was bad , thanks for help SOLVED!!!