820 3023-a shuts down at random

[Sr. Robot]

Hi, got a 820 3023-A that completely shuts down at seemingly random, just black screen, everything works fine but that. No signs of water damage. It even shuts down with everything disconnected.

 

[2informaticos]

Check if still shuts down in SMC bypass and safe mode.

 

[Sr. Robot]

Doesn't turn on on SCM bypass. Maybe I'm doing something wrong since its a 2011 model. Unplug battery, push power button, connect charger while still pushing power pushing power button for 10 secs, release.

 

[2informaticos]

SMC bypass succeed when fan starts with max speed.
Did you try safe mode too?

 

[Sr. Robot]

Shuts down on safe mode and SMC bypass mode too.

 

[2informaticos]

Which MLB voltages disappear then?
Are you using original 45/60W Magsafe 2 charger?

 

[Sr. Robot]

After it shuts down i get every voltage up to PP3V3_SUS. (When i measure PPBUS_G3H it shows 12.5v for an instant then goes to 8.4v)

PP3V3_S3 is gone.

Yes, OEM 60W magsafe

 

[2informaticos]

PPBUS_G3H drops to 8.4V without battery connected?
Still random shuts down with only charger, no battery?

 

[Sr. Robot]

PPBUS_G3H drops to 8.4V without battery connected? : yes

Still random shuts down with only charger, no battery? also yes

 

[2informaticos]

8.4V is the correct voltage for PPBUS_G3H.
You've probably measured it in wrong point to get 12V in the first moment.

Test resistance between pins 17/18 and 27/28 of U7000.

At the end, may be RAM problem.

Run corresponding ASD, just in case.
You can also try Windows Live USB, or Linux; to run some stress tests.

 

[Sr. Robot]

resistance between pins 17/18 = 3.4 ohms

resistance between pins 27/28 = 20.8 ohms

It passed ASD test.

 

[2informaticos]

What said the client about how the fault came on?
Run HWMonitor, or other similar software and monitor temperatures.

Try clean ME BIOS also.

 

[Sr. Robot]

No past information from the machine. Do you happen to have BIOS file ? Cant find any online.

 

[2informaticos]

Try this one.

820-3023 clean fix APFS.bin

drive.google.com

 

[Sr. Robot]

Thank you very much for the file.

Changed BIOS chip and tried both the original and the clean EFI files but still same issue.

 

[2informaticos]

Did you try Windows, or Linux on it?

 

[Sr. Robot]

Yes, it shuts down on linux also, but it takes way longer

 

[2informaticos]

There should be CPU issue.
Try to heat it and burn eventually accumulated crap underneath.
You can also reball SMC, just in case.

 

[piernov]

Can randomly try to replace C1802/C1803.

 

[2informaticos]

Ooops, I forgot about these caps.
If you find the voltage around 2.4V on any of them, there is the problem.
Normal voltage should be higher than 3V there.