820-01814 no backlight..

[yair37]

no water damage..
2 weeks ago there was short on PPBUS_G3H on C6406 and now suddenly there is no backlight..
PPVOUT_S0_LCDBKLT 0v
i see the apple logo and the user interface but there is no backlight..

 

[yair37]

?

 

[2informaticos]

What about BKLT_EN_R and BKLT_SD?
Did you test with known good LCD assembly?

Just in case, do PRAM reset 2-3 times.

 

[yair37]

BKLT_EN_R 3.3V
BKLT_SD 12.5V
i was try also with good know screen and cable
PRAM didn't make the job

 

[2informaticos]

Check diode mode to ground and voltage on BKLT_SCL/SDA lines.
Also check R8450-3 and their traces.

If Q8401 and D8410 are good, try changing U8400.
Be sure all traces around are good too.