[SOLVED]820-3115 No Backlight

[820Slave]

No Backlight
Flashing Folder
U9701 Changed

21+22 of J9000 PPVOUT_SW_LCDBKLT starts @ ~20v and falls to steady 12.54v in just about the same time flashing folder appears RTG at this point .567v
0.0v BLK_PWM
3.29v on pin 5 of q9707 LCD_BKLT_EN

Any assistance would be appreciated. Thank you.

 

[dukefawks]

PRAM reset done?

 

[820Slave]

I would have been quite embarrassed if it was indeed that simple after replacing U9701 with the same outcome, however PRAM reset didn't help. Still no Backlight.

Thank you very much for your assistance. It's great to have a resource such as yourself as these challenges can make you a tad MENTAL.

 

[dukefawks]

Any change to BKL_PWM? Resistance to GND on that line? BKL_EN present on R9715?

 

[820Slave]

No change to BKL_PWM / 0v
RTG @ pin2 of R9704 BKL_PWM = .5v
BKL_EN = 3v @ pin2 of R9715

 

[dukefawks]

Remove R9704 and connect pin 2 directly to 3V_S0. This should get the backlight working, just no adjustment possible.

 

[jadao]

I would tell you to check if smc_lid is high just in case the board thinks the lid is closed.
But not sure if it's an smc_lid issue since you have 20v at bklt output remaining few seconds...

 

[820Slave]

Duke, board was missing r5071 and bad c4906. Against my hunches I changed U9701 for nothing, thank you for teaching me the order of operations. Very grateful for your assistance.