Apple Event: May 7th at 7 am PT

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

Level 1

8 points

My 27" Imac (A1312/EMC2390) keeps shutting down unexpectedly with no warning or "screen of death". I replaced the power supply, reset the SMC, and zapped the PRAM, but the problem continues. Can anyone help me?

My 27" Imac (A1312/EMC2390) keeps shutting down unexpectedly with no warning or "screen of death". So far I reset the SMC, and zapped the PRAM. I even replaced the power supply but the problem continues. My error and system logs seem unhelpful too. Can anyone help me out?

iMac, Mac OS X (10.6.8)

Posted on Feb 26, 2013 8:55 AM

28 replies

MichelPM

Level 10

80,980 points

Feb 26, 2013 10:43 AM in response to afriedman

Something is definitely wrong.

Despite what AHT report.

I think it is time to bring your iMac into an Apple Store or Apple Authorized service center.

They will have better diagnostic tools to find your issues than I think any of us can do for you at this point.

MichelPM

Level 10

80,980 points

Feb 26, 2013 10:47 AM in response to afriedman

Something has failed or is failing if it is shutting your iMac down.

Could be the CPU. Could be the GPU. Could be a logic board failure.

When working on this iMac, were you using a grounding strap with it connected to some metal part on your iMac?

afriedman Author

Level 1

8 points

Feb 26, 2013 11:18 AM in response to MichelPM

Yes, I was grounded.

Several of these replies have suggested that it may be related to the replacement that I did. While I make no claims to infallibility, I need to reiterate that the shutdowns were happening before I ever opened the IMac's case. I would doubt that an errant spark or mis-seated plug would duplicate the original fault. More likely, that would have introduced some new error, or a complete failure to operate.

As far as the Apple store is concerned, that was always my fall back plan, but I'd feel ever so much more productive had I been able to fix it myself. Especially after ordering the new power supply.

On another thread, I found references to re-seating the RAM. I'm going to try that if it fails again. It's been on now for 4 hours plus, but I'm going to leave it on for several days before I put it back in service. Wish me luck.

MichelPM

Level 10

80,980 points

Feb 26, 2013 11:22 AM in response to afriedman

I pray for the best.

Wish you luck!

😉

afriedman Author

Level 1

8 points

Feb 26, 2013 11:38 AM in response to MichelPM

For what its worth, here are my fan speeds and temperature stats. See any issues here?

WZZZ

Level 6

13,226 points

Feb 26, 2013 11:52 AM in response to afriedman

The fan speeds look OK and nothing that would set off a thermal shutdown, although generally I like to keep things a bit cooler running. But that's not the issue right now.

The end user AHT is a poor, unreliable diagnostic.

MichelPM

Level 10

80,980 points

Feb 26, 2013 11:55 AM in response to afriedman

These temps look okay with just the automatic running of the fans.

The HD temp seems pretty high to me, though.

Everything else looks just okay to me

I am not a good judge of this though.

I Have a manual fans software control on my iMac because I feel most of these temps are just too darn warm and I worry about slow roasting the components on my iMac over time.

The problem is the iMac will auto shutdown if anything goes over 150 degrees F.

None of those temps are evn close to 150 degrees F.

So, I do no think it's a temp issue, but some other failing piece of hardware.

It maybe the RAM needs to be reseated.

Wouldn't hurt to try this, though. You never know.

afriedman Author

Level 1

8 points

Feb 28, 2013 8:13 AM in response to MichelPM

Here's a quick update.

It's been 2 days now and the computer has been left on for the entire time with no shutdowns! I'm going to leave it on until Monday before putting it back into service.

Wish I knew exactly what the problem was. Between the new power supply, OS reinstallation, Disk Utility repairs, SMC, PRAM and other attempted fixes, I have no idea exactly why it seems to be fixed at this time.

However, thank you all for your suggestions. I appreciate every one of them.

WZZZ

Level 6

13,226 points

Feb 28, 2013 8:16 AM in response to afriedman

Did you reseat the RAM?

afriedman Author

Level 1

8 points

Feb 28, 2013 8:23 AM in response to WZZZ

Never did reseat the RAM. Right now I'm just leaving it on and working on some test files with it to see if it crashes again.

I'll try the reseating it if it fails again, but I hope I don't have to. Then, if that doesn't fix it, I'm guessing a trip to the Apple store will be in order.

Jun 30, 2015 2:06 PM in response to afriedman

This starting happening to my iMac around the same time. I just stopped using it until after my macbook logic board died. Turns out the control board to the screen isn't working correctly. I took it in to maclife in boise and it was NOT the power supply. The solution? Replace the whole screen to the tune of $650!! We are just going to buy a used a screen or repair the control board. My husband is a electrical engineer who fixes airplanes. Much less/more complicated systems so this should be easy. the problem is finding the part! $300 on ebay.

what did you end up doing or finding out? I am asking out of curiosity. I hope you found an easier solution I could try in the mean time. blah

Oct 13, 2015 1:58 PM in response to afriedman

I have the same model 27" iMac (A1312/EM2390) that you had a shutdown problem with. The screen on mine just randomly goes black. At first it was the whole computer shutting down but now I can tell it's only the screen. I have reset the PRAM, reseated the RAM, run Apples hardware trouble shooting software to find no issues and I have just replaced the power supply. Noe of these things have fixed my problem. I think it's either logic or video board related or power management related. Not sure what else to do short of taking it to the genius bar.

Just wondering, did you ever figure out what it was that fixed your iMac?

Pulling my hair out.

Please reply at your convenience.

Thanks

Sep 23, 2017 5:59 PM in response to violagirl305

What do your console error messages say prior to the failure.

My 27" Imac (A1312/EMC2390) keeps shutting down unexpectedly with no warning or "screen of death". I replaced the power supply, reset the SMC, and zapped the PRAM, but the problem continues. Can anyone help me?