820-00165 has backlight but no image

[kevinklinkmuller]

small amounts of liquid damage in multiple areas. There is USB activity, chime is there, fans spin up when battery is disconnected as if it's booting. backlight is there. Tested with known good screen, nothing but backlight.

Also it doesn't seem to turn off backlight if I close the lid. So perhaps has to do with SMC lid?

 

[2informaticos]

Backlight present with black, or white screen?
Just in case, check SMC_LID level, when lid close/open.

 

[kevinklinkmuller]

sorry im wrong, lid is behaving, I think the IO board wasn't in properly

But screen is black with backlight
makes dong, seems like it starts too

 

[2informaticos]

Check all caps and resistors related with J8300.
Be sure to have good solders and traces.
You may need to change video connector.

 

[kevinklinkmuller]

hmm, they all check out perfectly, even checked diode mode on pins with known good board. I see that come components there communicate directly with SMC, do you think SMC can cause no image? there was corrosion on the SMC_onoff_L test point near the SMC

 

[kevinklinkmuller]

Video connector is pristine. No liquid damage near it

 

[2informaticos]

If you get backlight, PCH should be recognizing the LCD.
Just in case, check voltage on pins 14 and 18/19 of J8300.

You may have a communication problem on the I2C bus; check R8361-64 and diode mode on SCL/SDA lines.