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A1286 2011 820-2915 no video no backlight

V

VinceLx

Member
Hello,
This board in good conditions, no liquid damage visible.
Green light on charger, fans run, chime, USB activity on pendrive, but no display backlight and no video, no video also on external display.
PPBUS_G3H=12.57V
DP_MUX_EN=0V
PP3V3_SW_LCD=0V
PP3V3_S0=3.36V
LCD_PWR_EN=0V
PP3V3_S5=3.36V
GPUVCORE_EN=3.35V
LCD_BKLT_EN=0V
PM_ALL_GPU_PGOOD=3.35V
GMUX_RESET_L=3.35V

I imagine the issue can be U9600 or close to it, what can I check next?
 
2informaticos

2informaticos

Administrator
Staff member
Disable GPU in BIOS, instead od tedious job bypassing GMUX.
Keep in mind, BIOS mod will not survive to PRAM reset.
Also R8904 MUST be removed before applying power, after BIOS mod.

GMUX flash is the fastest way; no need to take out the board from shell.
Is PRAM resistant, but does not control backlight from keyboard.

Tiresias GPUkiller is the best option.
 
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