820-00840 no backlight

[Kyle93]

Arrived with liquid damage but at the time was still working. After cleaning up and replacing liquid damage components in U8400 area backlight is now gone. 0V on BKLT_EN_R.

Chimes and image appears on screen.

All traces appear to be fine. Replaced u8400 twice but no change. Really lost on this one.

 

[2informaticos]

EDP_BKLT_EN also low?

 

[Kyle93]

yes 0V

 

[2informaticos]

Check voltage and diode mode to ground on BKLT_SCL/SDA lines.
Be sure all R8450-53 are good, as their solders and traces too.