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Released October 2008 / 2.4, 2.53, 2.66, 2.8 or 2.93 GHz Core 2 Duo Processor

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Intermittent problem with computer switching off / not booting

Hi,

My MBP started switching itself off while asleep a while back. Now it has also started failing to boot intermittently (sleep light flashes once and fans spin up for 1/4 sec then everything abruptly closes down - no chimes etc.) Sometimes the computer will make it past chimes, but then powers off suddenly halfway through booting almost as if a short has occurred. I have had a local mac repair guy reflow soldering on the logic board, the issue got better for a day or two and is now back again. Laptop has not been subject to impact damage, spills, or any of the usual suspects although the repair guy mentioned some signs of heat damage. Any advice as to what this might be? Thanks!!

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Reset the SMC and PRAM. It could be a SMC or PRAM issue.

To reset the PRAM shut down the computer and hold the command, option P and R button while it boots at the same time. Doing this will cause it to restart and reset the PRAM.

here is how to do an SMC reset

If this doesn't work, clean the dust and put new thermal paste on.

Here are the guides to remove the fans.

MacBook Pro 15" Unibody Late 2008 and Early 2009 Left Fan Replacement

MacBook Pro 15" Unibody Late 2008 and Early 2009 Right Fan Replacement

MacBook Pro 15" Unibody Late 2008 and Early 2009 Heat Sink Replacement

As the tech said there may be heat stress damage in the laptop. If what I suggested doesn't help take pictures of the logicboard for us to look at.

MacBook Pro 15" Unibody Late 2008 and Early 2009 Right Fan Image

Guide

MacBook Pro 15" Unibody Late 2008 and Early 2009 Right Fan Replacement

Difficulty:

Moderate
MacBook Pro 15" Unibody Late 2008 and Early 2009 Left Fan Image

Guide

MacBook Pro 15" Unibody Late 2008 and Early 2009 Left Fan Replacement

Difficulty:

Moderate

—

30 minutes - 1 hour
MacBook Pro 15" Unibody Late 2008 and Early 2009 Heat Sink Image

Guide

MacBook Pro 15" Unibody Late 2008 and Early 2009 Heat Sink Replacement

Difficulty:

Difficult

—

1 - 2 hours

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Thanks for the reply. I tried the SMC and PRAM, no dice as the computer won't get far enough along the boot process (no gray screen). Also the tech cleaned the fans when the board was serviced.

When you say RSS on the thermal paste what do you mean?

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I inspected the logic board and found no obvious burned components or traces - the only signs that I guess could be heat damage are "rainbow" effects on empty component pads.

Heat paste appears to have been applied and the temperature reads OK across all sensors in Istat.

Any ideas from here on out? The issue is still there but intermittent: one of three things happen

1) Won't boot at all, sleep light flashes for 1/4 sec (as above)

2) Boots past chimes to grey screen, then abruptly powers down just before the blue screen appears within OSX

3) Boots just fine

Once it's booted it does not switch off during use at all. Sometimes it will power off when waking from sleep.

Bizarrely it seems that the longer you leave it after a failed boot attempt, the more likely it is to boot OK.

I tried bypassing the SMC on boot (remove battery, hold power key, connect magsafe, release and then re-press power key) but this did not help, the fans just spin up faster for 1/4 sec.

When it did boot, Apple Hardware test was left looping overnight and found no issues.

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You had an idiot &&^& up your board. Instead of actually diagnosing what was wrong, he just heated things up and probably made it worse. As most who aren't clueless know the issue with BGA chipsets lies inside the die, not the actual solder balls connecting it to the board. Heat damage occurred from idiot!

He probably heated up the MCP79MXT-B3, which I would replace after that idiotic nonsense. Also the mux is directly under this which hopefully did not get F'd up by that "fix"

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