820-3115 - No Backlight

[Palhano]

Mac arrived without screen backlight.

F9700 bad and with a short in the line of the C9799! Replace both. I got 12.56v again on the backlight line. Then find out that pin 3 of the Q9706 was 12.56v. Replaces the Q9706 and now I have pin 3 - 4v and on the others, 12.56v. But no backlight.

I tried with another screen, same problem.
I had already checked reset PRAM!
Checked Trails - Okay
F9700 - Okay
D9701 - Post-diode p2 .607 - P1 .405 - With and without screen
Something wrong! D9701 - P2 starts at 12v and goes down - P1 12.56V

Q9706 - 1, 2, 4, 5 and 6 - 12.56V / 3 - 4V
L9008 / L9004 - 3.27V - Both pins

R9704 is good!
BKL_EN - 2.9V
BKL_PWM - 3.3V

 

[2informaticos]

Check the traces D/U9701.
Change U9701.

 

[Palhano]

I checked the traces, all ok.

I changed the U970, but it didn't work! I also reset the PRAM again

 

[2informaticos]

12V on backlight output means backlight is enabled, just not boosting.
Check all return resistors, be sure U9701 is properly soldered.
May have bad LCD connector.

 

[Palhano]

I tried changing the D970 and it worked!

Thanks a lot for the help!