주요 콘텐츠로 건너뛰기

2011년 하반기 모델, A1278 / 2.4 GHz i5 또는 2.8GHz i7 프로세서.

584 질문 전체 보기

Help repairing logic board 820-2936B

Hello,

My trusty 13-inch late 2011 MacBook Pro has finally had enough and called it a day after 11 years of loyal service.

Late last week while I was quietly watching a film, the screen started glitching out of nowhere and the Mac started beeping 3 times at 2-second intervals before either shutting down or restarting. This has been happening non-stop since last week. If I’m really lucky, I can maybe get 5 or 10 minutes of usage before the bugger starts again. Sometimes it’s glitching and beeping, sometimes it’s glitching alone and other times it’s just the beeps.

I’ve tried reseating the RAMs, switching RAMs, trying one RAM at a time in each slot, trying factory RAMs, trying entirely new RAMs … nothing helps. Ditto same tests in safe mode, and the Mac is still glitching and/or beeping. Working from the hypothesis that it’s a hardware issue, I ran Apple Service Diagnostics 3S148 in both OS and EFI modes but all tests came back normal. I’ve reset the PRAM and SMC more times than I care to count to no avail.

The Mac boots up in the sense that when I press the power button there is a startup chime and the screen’s Apple logo lights up. So presumably it passes POST. But then it either starts glitching/beeping immediately or after 5-10 minutes of usage.

I did notice that the battery, which I should’ve replaced in 2016 but didn’t, was for some reason causing the core CPUs to heat up to 90-100 C on startup. When I removed it and only ran the Mac on the power adapter, the core temps immediately dropped to 50-60.

So my current working hypothesis is that this continuous excessive heat has partially fried something on the logic board, but I can’t figure out what exactly. I did visually inspect the logic board for any burnt components or corrosion but didn’t note anything out of the ordinary. My brother, who’s into electronics, has volunteered to help and acquired the board’s schematics.

Where do you think we should look first?

Thanks.

이 질문에 답하기 저도 같은 문제를 겪고 있습니다

좋은 질문 입니까?

점수 1
댓글 달기

답변 1개

가장 유용한 답변

What you are describing is a race condition!

So let's say your battery is not working at the correct level, what logic would likely kick in to off set the low voltage? That would be the VRM circuit.

But before you dig into the logic you need to first correct the obvious! I would replace the battery first if you think thats the issue. How about checking it using this app! CoconutBattery take a snapshot of the apps main window and post it here for us to see Adding images to an existing question

해당 답변은 도움이 되었습니까?

점수 1

7 Comments:

Hi Dan,

Thanks for your reply. I did check the battery's status with Coconut Battery last week but did not screenshot the data. And since the Mac is acting up, I can't go back in and redo the test (I'm currently using a different MBP). I do remember that both 'full charge capacity' and 'design capacity' were in the red, that the battery's status was poor and its load cycle higher than 1000. Does this help?

Unfortunately, I am currently abroad and do not have access to reliable Mac parts so that rules out changing the battery in the foreseeable future. I will ask my brother to check the VRM circuit and report back. Thanks again for your help.

@siriusblack - Yes! You need a new batt for sure!

Just a idea

I was looking at the question and notice they mentioned beeping so may that mean a p ram battery being dead

I know that that macs beep on boot when their p ram batteries die but the question says it’s not on boot

I thought it may be something to do with it because of the age of the device

But it’s just a thought

Hopefully it’s useful

Thanks:)

@hellomacos - The unibody systems use the main battery to hold the PRAM/NVRAM settings.

Hi thanks for letting me know:)

2에 댓글 더 나타내기

댓글 달기

귀하의 답변을 추가하세요

Sirius Black 님은 대단히 고마워 할 것입니다.
조회 통계:

24 시간 전: 0

7일 전: 0

30일 전: 0

전체 시간: 62