MBP A2338 - board 820-02020 No image int.

Mortentoft

Member
Hi' everybody. I have a M1 MBP from 2020 with a liquid damage. CL053 PP3V3_S2_WLBT_ISNS was shorted, replaced and now the MBP is running. I get image on external screen but not on internal. I have tested on other known good display without any image. Testet in known good housing as well - no luck. On the old MB you easily see if it is backlight. But not anymore:).
Any suggestions where to look first? I looked at schematics but I can not find any issues. Thank you in advanced.
 

2informaticos

Administrator
Staff member
Missing image and backlight at same time?
LPDP_INT_HPD goes high?
Do you get any voltage at PPVOUT_LCDBKLT?
 

Mortentoft

Member
Hi again. Sorry i answer you so late but I was out of Office when you wrote.

LPDP_INT_HPD is = 1.15 v stable
PPVOUT_LCDBKLT = approx 12 v dropping fast to allmost nothing. Not good i suppose🥵
 

Mortentoft

Member
Yes… still a drop. Slow drop… but I can not see failures on the mentioned traces. But something/somewhere it drains for voltage on that line.
 

2informaticos

Administrator
Staff member
If starts dropping from 12V, means that UP800 enables QP800 at first moment.
Some problem is detected and is disabled.
Check DP800 and QP800/801.
Be sure all adjacent resistors and traces are good.
 

Mortentoft

Member
Hi’ I have an issue on th QP800. The enable pin on UP800 is 1,2 volt. But it keeps shutting down. I need to find a donor and then I will let you know. Thank you 2Informaticos for yiu Gold nuggets until now:).
 
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