820-00163, Lid sleep issue

[ALB-Repairs]

I have a 15" Retina DG here.
It works perfectly until we put it in LID sleep.
When you open the LID the keyboard backlight comes up but the screens backlight does not, I have measured the backlight line and after coming out of sleep its showing 50V / No load.
Not seen this one before.

 

[Paul Daniels]

Fake the lid closure using a magnet, see if it does the same. I'm half wondering if it's just the cable shifting and disconnecting or something.

 

[dukefawks]

Yeah, I would say a bad cable/connector/LCD.

 

[ALB-Repairs]

Fake the lid closure using a magnet, see if it does the same. I'm half wondering if it's just the cable shifting and disconnecting or something.

Goes to sleep, wakes the keyboard backlight but not the screen.

 

[ALB-Repairs]

Yeah, I would say a bad cable/connector/LCD.

Ive tested a known good screen, Same behavior.
I also suspected that so replaced the connector as i suspected exactly the same. Sadly it made no difference.

 

[dukefawks]

Are you sure this is a 2015 LCD that is on there and that you used for testing. 2014 LCDs will also give these weird backlight issues!

 

[ALB-Repairs]

Are you sure this is a 2015 LCD that is on there and that you used for testing. 2014 LCDs will also give these weird backlight issues!

Yeah, i know all about that, Tested with original screen, and a working but blotchy 2015 15" screen.
going to do some digging in the schematic and see what i turn up.

 

[dukefawks]

50V would suggest the driver section on the board is fine. What could be causing the issue is the chip that controls the return lines which is in the LCD and is controlled through the 2 i2C lines going from the backlight chip into the LCD.
So either something up with those data lines/traces or connector or as a last resort the backlight IC.

 

[ALB-Repairs]

50V would suggest the driver section on the board is fine. What could be causing the issue is the chip that controls the return lines which is in the LCD and is controlled through the 2 i2C lines going from the backlight chip into the LCD.
So either something up with those data lines/traces or connector or as a last resort the backlight IC.

Yeah, I thought it could be i2C lines. Its proving a tricky fight. The only other thing ive noticed is that this takes an eternity to boot. Im kinda suspicious of the Bios causing that as there was a decent amount of liquid damage around the bios chip.
this one is driving me a bit mad!

 

[ALB-Repairs]

I have a headache!
Ive seen 00165's and 00164's with strange slow booting problems after liquid damage around the SPI.
I spent half my afternoon on this board, Found another known good board, Tested it in the shell from the problem Mac. All worked

Purposely swapped the Bios chips to test the known good board with bad ME region. A known good board with a Bad ME region does exactly the same as my liquid damaged/ problem machine!

At this point im fairly certain the liquid damage board has a corrupted ME region and thats causing the strange sleep issue!

 

[dukefawks]

Could very well be, internal diagnostics should pick up a non working ME. Upload original BIOS to be fixed.