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l008com · Aug 30, 2013, 04:10 AM

So I was given this 2009 macbook pro to recycle. It was in rough shape, so I was just going to dump it to the recycler. But one slow day, I decided to check if the screen worked. I was hoping it would boot just so I could see if it was cracked. It did boot, the glass was cracked but not the screen. I had to throw some old RAM in there, and I netbooted the system off my server. It ran. And ran well. So well, that I started fixing it up. Peeling off all the stickers, cleaning off all the dirt and guk. Replacing the glass, getting some missing screws like the HD screws and some trackpad screws. All the while, for about a month, I had the machine running very reliably. It was mining litecoins so it was creating a lot of heat. And I had the fans running at a higher than normal speed to maximize airflow. I'm assuming this was a liquid spill Mac but I don't know. But for a month it was great. I tested it very thoroughly and decided it was good to go.

I've had a hectic week. So today I looked at it and noticed it was off. So I turned it on and after a short time, it suddenly powered off instantly. So after a lot of troubleshooting, I determined it shuts-down with or without the battery installed, and it shuts-down no matter what internal hard drives it boots off of (swapped two). But if I netboot it, it seems to run normally.

Both hard drives are SATA drives pulled from other Macs. It's definitely not a software issue. The computer doesn't "shutdown" in the soft sense, it instantly and abruptly powers down.

So what do you think? The HD cable and connections all look fine. I sure hope the SATA bus on the logic board isn't fried. I spent a lot of time working on this machine back when it was working perfectly, I put that time in expecting to get my money back when I sold it.

Here's a video of it happening:
IMG 2764 - YouTube

l008com · Aug 30, 2013, 04:34 AM

A little more info: When I do netboot, the machine runs fine and doesn't shutdown. But the internal hard drive is still in there, running, and accessible. It passes all hardware checks and I can access the files. But when I boot off of it (or any other internal drive), I get the sudden shutdowns.

Spheric Harlot · Aug 30, 2013, 04:35 AM

That's bizarre.

Netboot working but not various local systems is really weird.

Will it run off an external drive via USB?

l008com · Aug 31, 2013, 04:11 AM

Yup. Powers off, abbruptly, when booting off USB. It also powers off when netbooting too. Just less. It lasts longer via netboot.

l008com · Aug 31, 2013, 04:20 AM

Well that was an interesting clue. I had the machine netbooted. With the internal and external drives present and just sitting idle. I was going to see how long it would run on battery power but once I got board of that, I plugged it in and prepared to move on to new things. The instant I plugged it in, it shut down. Could be be the Magsafe board faster all, that's causing the problem! Oh joy, a cheap $20 fix! Could I be so lucky!

P · Aug 31, 2013, 09:09 AM

My guess is that the southbridge (well, OK, that computer has NB and SB in one chip, but the SB function then) has a defect, possibly related to cooling. Take a look at that heatsink to make sure it is fastened correctly, has the right amount of cooling paste, etc.

l008com · Aug 31, 2013, 02:41 PM

I don't think it's cooling related, because it ran a litecoin miner for weeks straight and was just fine. And now suddenly, whenever I plug in AC power, it shuts down within seconds.

P · Sep 1, 2013, 08:27 AM

If you're running the litecoin process on the main CPU, it could still be - the south bridge is in a separate chip (in fact, is on all Macs except the latest Haswell MBAs). Obviously if you're running it on the discrete GPU, the same thing applies. It's only if you're running that process on the integrated GPU that you will heat up the south bridge.