820-3330 - No backlight - J9000 pin 38, 39, 40 (20V)

[nelo1012]

Have 820-3330 15" MacBook pro,

F9700 - 10.89V on both sides (with battery) , 12.56V With power cord

J9000 pin 38, 39, 40 (20V)

Got image, just no backlight

any ideas?

 

[nelo1012]

I also ran a wire from Q9701 (LCD_BKLT_EN) to R9704 LCD_BKLT_PWM

and it turn on then, but that would stay at full brightness at all times.

would this be a faulty U9600?

 

[smiba]

Ok so let me get this straight, you just combined LCD_BKLT_EN and LCD_BKLT_PWM? Uhh alright

LCD_BKLT_EN is a High or Low signal enabling the Backlight circuit
LCD_BKLT_PWM (PWM being Pulse Width Modulation) is the signal that tells the backlight how bright it should be.

Of course when shorting these two together you won't be able to control the brightness... I'm also not sure if U9600 likes this, you might be damaging its PWM pin

If you have 20V on PPVOUT_S0_LCDBKLT you should have working backlight, are the measurements in your title taken with the _EN to _PWM short or without?

 

[dukefawks]

Did you do a PRAM reset? If that does not help then it could be either the LP8550 pulling the PWM signal down or U9600, a leaky C9704 would also cause issues.