3 Random shutdown, won’t power on until left to sit
I was gifted a broken MacBook Air early 2014. I was thrilled when it fired right up, only to find that it would randomly shut down. Once shut down, it won’t power on right away, but will if left to sit for a bit.
I’ve tried blasting it with a fan tray to see if it was a thermal issue, and also removed the logic board and cleaned with alcohol. I’ve also done SMC and PR resets. The behavior seems to be unchanged.
The maddening part is that it will work briefly (or sometimes longer), but eventually always shuts down. It never starts up again right away, but eventually (after a long wait) will power on again. The power on is also slow - if I sit and watch with the bottom cover off, I see the fan spin up, stop, spin up, stop and finally spin up , chime and boot.
Is this a good question?
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5 Comments
since you have it open, have you tried to let it run without the battery connected? see if that changes anything.
by jostewcrew
Thanks for replying! I forgot to mention that, but yes I’ve run it with battery disconnected. The issue appears both with battery only and battery disconnected.
by David McGlynn
sounds like a component on one or your rails is heating up and failing after boot. i would grab a multi meter and check around. everything is ran of of your main 19v.....i would check this is present first. then id look for your 5v, 3.3 and so on. whats the model number ? a****
by jostewcrew
It’s A1466. I haven’t used my multimeter in forever but can take a crack at it. Is there a manual for where test points are? I had a similar thought, but wouldn’t expect the computer to be unstartable for that long.
by David McGlynn
you can find this schematic online.just type your model number along with schematic and you can download. the main diagram will help you starting out, then 2 pages of test point and always present rails will help you hone in after. you can test your voltages anywhere on the board. just make sure that you are finding all rails present starting out… 14.5 is the main it looks like, this feeds all other rails in the system. so when the unit is plugged in, start testing components in this line and then move to the 5v and 3.3 and so on. there are voltage references in the diagram. if you find anything missing, we can investigate further as to why and see what function it has. if anything is heating up really hot or smoking or looks burnt, this is a indicator of where the issue is. post back with findings for any further assistance.
by jostewcrew