820-2850-A can't adjust the backlight

arash

Member
The backlight is always on 100%, we have changed the graphic chipset, frame buffer cap, Graphic power controller and backlight driver with no success, any ideas?
 

2informaticos

Administrator
Staff member
Try PRAM reset first.
Check PWM signal at U9701 (pin 2) when press backlight adjust keys.
DC scale good enough to see the variation.
 

arash

Member
PWM signal is present, but it doesnt vary.
It also doesnt show it in osx when i press one of the two keys.
 

2informaticos

Administrator
Staff member
Backlight is adjusted through GMUX (U9600).
Reflow it and change with one from donor board, if no result.

One thing, does this machine has EFI password?
 
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