820-02016 - Intermittent Display

[ronaldo]

Hi. Please help.

M1 MacBook with intermittent display, but backlight stays on.
The display stays on for about 1 minute and goes off. Tested with 2 other displays and same issue.
External monitor works fine.
PPVOUT_LCDBKLT - 43.45V after display goes off.

Tested all EDP and LDDP lines in diode mode, and it matches with OpenBoardata values.

PP3V3_SW_LCD - 3.14V when display is on, then goes to 3.23V when display goes off.

Any idea of how to fix it?
Please
Thanks

 

[2informaticos]

Possibly problem with data cable inside LCD assembly.
It also fails, not only backlight flex.
Recently confirmed by a friend; however not sure if was M1 machine.

 

[ronaldo]

You mean the lcd is faulty?
But I tested with another 2 lcd display and the same is happening.

 

[2informaticos]

Changed the small video cable too?

 

[ronaldo]

I've tried with another cable and same issue.

 

[2informaticos]

Both 3V3/5V_SW_LCD are stable?

 

[ronaldo]

PP5V_SW_LCD - stable
PP3V3_SW_LCD - 3.14V when display is on and 3.25V when display is off.

I've replaced UP701 just to check if it would get any difference, but still same.

 

[2informaticos]

Lid detection failure should affect backlight too.
But, just in case, monitor LID_OPEN and AMR_LEFT/RIGHT signals.

 

[ronaldo]

All 3 lines has same voltage after display goes off.
LID_OPEN - 1.16V
AMR_LEFT - 1.56V
AMR_ RIGHT - 1.56V

 

[2informaticos]

I think LID_OPEN should be a bit higher, closest to 1.8V; just compare with good board.
Also check it disconnecting trackpad cable.

 

[ronaldo]

I was testing without trackpad.

RR313 - LID_OPEN/SMC_LID_OPEN_R - 1.16V
RR203 - IPD_LID_OPEN_1V8 - 1.8V

I don't have another board at the moment to compare.

 

[2informaticos]

Save data and check if DFU restore helps.

 

[ronaldo]

I don't know what's going on here.

After DFU revive it went to activation lock screen and guess what, no more screen issues.
Then I went through the activation process to activate the mac and for this I had to set up a Wi-Fi and instantly after turn on Wi-Fi screen went off.
I connected to an external display and turned off the Wi-Fi and closed and opened the lid, display is fine.
So, now I know that if Wi-Fi is on, the screen goes off. Turn off Wi-Fi, close and open the lid, screen works fine.
I have no idea what else to do.
Please help. What's the relation between screen and Wi-Fi?

 

[2informaticos]

Did you confirm this issue several times?
Is there any way to do DFU restore?

 

[ronaldo]

Yes, I've tested many times and even checked by someone else to make sure I'm not .
I've done only revive option. This issue I'm mentioning is on restore screen before install system.
I will do dfu restore on Monday.