Intermittent shutdown: overheat or keyboard short?

Hello,

I have a late 2010 MBA which occasionally pops up a dialog box asking "if I want to shut down" then turns off by itself.. I can not interrupt the shutdown sequence. The laptop was bought used, although in great cosmetical shape and with a 256 Samsung SSD. On software side it's running Mountain Lion with all software and firmware updates installed.

Now I know enough to conclude this is some intermittent electrical issue, probably a power button short. What is interesting, the shutdown dialog doesn't appear if I hold the Fn key pressed. Now I literally need to put something heavy on it all the time because the frequency of this issue has increased to many times per minute. Note there has been a similar issue on the stackexchange forum: http://apple.stackexchange.com/questions... and top case replacement was suggested.

I took the laptop to a private person who specialises on Apple gear here in Vienna and he did some diagnostics, tried running with disconnected internal battery etc.

What we noticed with case open is that the cpu is getting really hot. He concluded it is most certainly not a keyboard, but thermal issue and recommended renewing thermal paste. However, running temperature monitor I see that idle cpu is 55C degree hot, with youtube paused about 77C degrees, under load 85-90C degrees.. which is pretty hot, but not extreme so I am not convinced.

If replacing the grease doesn't cure the problem I'm not sure this person will be able to help me, so I'd rather find someone who has more extensive experience before paying $$. I'm gonna run some kind of memtest overnight, but I don't really expect it to find something. Yes, I got a BSOD a few times, but this started happening after enabling FileVault encryption and I attributed that to incorrect shutdown.

1. What do you think is the problem? Shall I attempt to get the keyboard cleaned or replace thermal grease? I'm not 100% sure about either option. The 0 and [ keys have been sticky when I got it, the power key however seems perfectly clean.

2. How difficult is it to replace thermal grease on MBA 2010? I did that on Lenovo laptops a few times but have no tools for Apple. Shall I pay 50 EUR for the job or attempt to do it myself?

3. I'm searching somebody specialising in MacBook repairs ideally from Germany or Austria. I know there is remacberlin on ifixit, but I have no idea how to contact him..

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Andrew -

Your problem could be a rogue program running in background stealing CPU cycles which is causing your system to overheat.

Try this - Make a fresh OS install on a USB drive from the installer program. Then alter the startup disk so this drive is used. You will need to run a temp monitoring program to see if it's over heating still (running off of the USB drive). Try not to run anything off of your internal drive for this test. Is it running better?

If it is then you'll need to figure out what is chewing CPU cycles. Use Activity Monitor to see whats doing you in. At worst you'll need to reformat the drive and re-install your OS and Apps.

I would also recommend limiting File Vault just to a set of folders Vs the entire drive.

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I would focus on the software side first before worrying about your shutdown issue as it could be related.

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Hi Dan, in fact I always keep my eye on the activity monitor or 'top' program. In fact I earn my living as a Linux software engineer.. there are no cpu hogs on this machine. My preferred metric for system load is load average (LA) reported in top. When the computer is idle the LA is about 0.24 and there are no programs taking more than few percents of cpu in top or activity monitor. The temperature is 55C degrees, maybe 50 if i leave it in this state for some minutes. When working with a browser and mail program the LA figure is around 0.46 and cpu temp is at 60C degrees. Should I de-press the Fn key, the shutdown dialog box pops up in a few seconds.

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While cleaning and applying a fresh coat of thermo paste on the CPU might help in lowering the temp a bit, I don't think that is your root issue here.

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Have you tried running off the external drive yet? While I do understand you don't see anything running as the top process. Something still could be doing you in here.

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Dan, just got around to running of the external usb drive, same problem. The computer shutdowns already at the language select dialog.

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I suspect this is a water damaged unit, keyboard especially

The temperature is normal for this computer, MacBook Air usually idles at 45~55c when viewing flash web content it is easy to rockets to 80c

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Thank you Tom, this is what I'm trying to find out.

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Hi Andrew!

I have exactly the same problem with my mpb.

I got shutdown messages every 5sec. And after trying reinstall OSX my laptop doesn't start.

I can start only ASD EFI, but ASD OS not.

I disconnected my HD and battery, but laptop still doesn't start :(

Only when I've found your post I tried to start with Fn pressed and I've got ASD OS started!

Uhhh...

Now really I doesn't understand what's up?

Did you find out anything?

Why it's happend?

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Hi Dmitry,

I have not found the cause of the problem, but the problem magically stopped happening on its own a few months ago.

It has only powered off once in the last couple of months. I took the laptop on some trips and it still works (although running hot in this hot weather..).

Really strange thing.. Regarding your problem, are you the first owner of your laptop so liquid damage to keyboard is out of question?

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Andrew,

I'm not the first owner of this laptop but I'm sure that last 1.5 years I have not liquid accident this it.

I really don't understand about Fn key.

I know that Fn+power combination in OSX uses for showing of "shutdown dialog" and I don't understand why Fn key pressed helps to startup without problem and while I press it shutdown dialog window doesn't shows.

I disassembled macbook and cleaned up power button, cooler, pointed that It's really hot during startup and I'm going to renew thermal paste.

But I think the problem is something other..

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Hi, I do have same shutdown issue, I'm placing an object in unused key to prevent shutdown...

Is there a permanent solution

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@Manoj - How about creating your own Question here with your details you may have a different issue.

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Hi, i resolved my issue... Just replace keyboard and your are done....

I found keyboard was water damaged unknowingly.......

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i have MBA 13 1,7ghz i5 2011

and if fans on max work ok, if are not

MBA just stop work and temp id on 97c!!

what can i do??

tnx

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@ bizachy - You really need to post your own question here with all of your details.

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tnx Dan.....

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