Finding my iMac powered off in the morning

[Raist3001]

My late 2015 iMac has suddenly been powering off at random times. I mostly find out its off in the mornings. I am unable to power it back on by pushing the button and the only thing that allows me to power it back on is if I remove the plug from the back of my iMac, wait for about 30 seconds, then plug it back in. My iMac will then boot up. I tried resetting SMC and PRAM.

Question is, is their any logs that could help me determine what is happening? Maybe I have a bad power supply?

 

[SecuritySteve]

When you power the machine on again successfully, do you see a "Report this Problem to Apple" window? If so, there will be a report as to what caused your crash in either ~/Library/Logs or /Library/Logs that matches the output you see if you had pushed the "Report..." button and expanded the drop down on the "Report this Problem to Apple" window.

 

[Raist3001]

When you power the machine on again successfully, do you see a "Report this Problem to Apple" window? If so, there will be a report as to what caused your crash in either ~/Library/Logs or /Library/Logs that matches the output you see if you had pushed the "Report..." button and expanded the drop down on the "Report this Problem to Apple" window.

Thanks for replying Steve. I do not see any message asking me to report this problem to apple. I will check the ~/Library/Logs and /Library/Logs. Can I view those in console?

 

[SecuritySteve]

Yes you can. The type of logs I have in mind will stand out with yellow alert signs over their icon.

 

[Raist3001]

Yes you can. The type of logs I have in mind will stand out with yellow alert signs over their icon.

Great, thank you Steve, Ill update tomorrow

 

[redheeler]

My late 2015 iMac has suddenly been powering off at random times. I mostly find out its off in the mornings. I am unable to power it back on by pushing the button and the only thing that allows me to power it back on is if I remove the plug from the back of my iMac, wait for about 30 seconds, then plug it back in. My iMac will then boot up. I tried resetting SMC and PRAM.

Question is, is their any logs that could help me determine what is happening? Maybe I have a bad power supply?

Yes, the symptoms you described definitely hint at a power supply issue. If your iMac is still covered under AppleCare, make an appointment and take it in to the Apple store.

 

[tubeexperience]

We had this exact same problem.

It's a power supply issue.

___________________________

If you are taking it to Apple for repair, make sure to take photos before hand.

Apple broke the display and then claimed that it was already cracked.

Thanks to due diligence, we took photos beforehand and didn't have to pay for Apple's mistake.

 

[Raist3001]

Yes, the symptoms you described definitely hint at a power supply issue. If your iMac is still covered under AppleCare, make an appointment and take it in to the Apple store.

Yep, still under AppleCare. I will make an appointment.

We had this exact same problem.

It's a power supply issue.

___________________________

If you are taking it to Apple for repair, make sure to take photos before hand.

Apple broke the display and then claimed that it was already cracked.

Thanks to due diligence, we took photos beforehand and didn't have to pay for Apple's mistake.

Thanks. I also have 2 blown pixels. I'll have both issues repaired. Great advice in regards to the pictures.

 

[Raist3001]

Brought my iMac into apple this past Friday. The Genius was having some problems as he could not duplicate the power issue. He ran hardware diagnostics and a few other tests and said the iMac was healthy. Obviously it is not since it is powering off every day. He claimed it was a sleep issue with the iMac. I simply asked him to explain that if the iMac was having trouble waking up from sleep, why am I not able to hard reboot my iMac with the power button? He thought for a second and agreed to take in my iMac. Since I would need a new display anyway for the blown pixels, it would be prudent to examine the power supply once the iMac is open.

 

[Raist3001]

Apple is telling me that becuase I had a few blown pixels, I have a display issue which inadvertantly is causing my power issue?? They are replaciong my display. Huh?

 

[Raist3001]

UPDATE
Apple replaced my Power supply and my display.
At first, they insisted they could not re-produce the power problem and were not going to replace the power supply. I expressed that if I brought my iMac home and experienced the power issue again, I would not be a very happy customer who again needed to lug his iMac back to the apple store. The manager agreed to replace my power supply as well.

 

[parisinvest]

UPDATE
Apple replaced my Power supply and my display.
At first, they insisted they could not re-produce the power problem and were not going to replace the power supply. I expressed that if I brought my iMac home and experienced the power issue again, I would not be a very happy customer who again needed to lug his iMac back to the apple store. The manager agreed to replace my power supply as well.

you are lucky they've changed the components, i've met the same problem on my imac 27 2012, it did random restart itself 4 or 5 times a day, and i've tried everything you've done, smc pvam etc, even changed the cpu termic, and open the ram slot and power on to suffle the dust, but nothing changed, until i cleaned the dust inside of main fan, and the dust inside by the bottom of imac, under the power unit and mother board, after that it wont restart again alone, so it was the over-heat cause the problem, cause i've never clean it after bought from 2012, this may give some others a clue to solve their problems.

 

[cobracnvt]

Did you ever try holding the power button in for more than 10 seconds to do a forced restart instead of unplugging it? It may have crashed hard and just wouldn't wake up.

I hope their fixes took care of the problem for you.

 

[Raist3001]

Did you ever try holding the power button in for more than 10 seconds to do a forced restart instead of unplugging it? It may have crashed hard and just wouldn't wake up.

I hope their fixes took care of the problem for you.

Yes, I tried the hard reboot by holding the power button for 10 seconds and longer. I was unable to power up my iMac by this method.

 

[RyanXM]

Yes, I tried the hard reboot by holding the power button for 10 seconds and longer. I was unable to power up my iMac by this method.

Have you had the power off overnight issue since having the power supply replaced?

I've seen this symptom be caused by the following: bad power supply, bad power button, and thermal related shutdown.

 

[Raist3001]

Have you had the power off overnight issue since having the power supply replaced?

I've seen this symptom be caused by the following: bad power supply, bad power button, and thermal related shutdown.

Picked up my iMac on 07/03. I have not experienced the shutdown since. Hopefully the replaced power supply was the issue.

 

[Raist3001]

I should note that when I received the iMac back, I installed High Sierra to an external SSD and made this my boot disk. Apple suggested that if the power issue happens again, I should reinstall OS X.

Well, I just started experiencing the shut down issue again. All seemed fine for a week, but the issue came back yesterday morning when I found my iMac powered off. Only way to power it back on was to unplug, wait 10 seconds then plug back in. When I got home from work yesterday, the iMac was again powered off. Again, I unplugged and replugged. This time, the iMac would boot, then in about 10-15 seconds, would completely shut down. I ran hardware tests (holding down D on boot up) which found nothing. Curiously, the iMac did not power down during these tests, which lasted about 5 minutes.

I tried moving my iMac to different wall outlets in different rooms. My iMac powered off at each location so I can rule out the wall outlet. I tried booting from a different OS and different HDD, so I believe I can rule out the OS as the issue as apple believes this is a sleep problem. If it were I should still be able to power cycle the Mac with the power button. Which does not work.

I have another appointment this Friday to lug my iMac back to the apple store where I hope they can fix it for good this time. I recorded one of the shutdowns so I can at least show the genius that I am not crazy, and this is indeed happening.

 

[mj_]

Making a video of that issue is always very helpful. I've had a really weird problem with my 2017 iMac where at random times during the day the screen suddenly doubled the horizontal resolution, meaning that a) everything was stretched, and b) I only saw the left half of the screen contents. Since it was impossible to reproduce I mounted my iPhone to a tripod while working and eventually caught it on video. Made an appointment, took it in, and the genius was very thankful for the video and replaced my iMac without further hesitation or questions.

 

[MasConejos]

I’ve been having a similar issue lately on my 2010 iMac, where I check it in the morning and it is off. It would restart normally with the power button (unlike yours). On restart, sometimes I would have a notification about unexpected shutdown, sometimes there would be no notification.

Looking into the details of one of the times I did get the notification, it appeared to be a sleep or wake from sleep issue. After a bit of research, my current fix is to leave Amphetamine running to prevent the computer from going to sleep (display still sleeps). It’s been almost a week and I haven’t experienced the issue again.

I’m debating replacing the power supply, but I’m not sure enough that the power supply is the issue to spend the $150 a new one would cost, especially given that I plan on replacing the iMac whenever Apple gets around to releasing new models (my personal guess for new models is late November).

 

[AndrsnH]

These issues seem to be becoming more common. I've had the same problem with my late 2015 5K iMac. It has also been experiencing the same power issues where the computer will turn itself off and nothing shows in the console/logs.

Even though it is covered with AppleCare (I'm in the UK) I've had a battle to get the store to actually do something about the problem. I had a screen replacement last year because of dead/stuck pixels, and at the same time Apple also replaced the logic board. Couple of months later the power off issues started.

In the first visit they re-installed the OS as they couldn't replicate the problem. - didn't fix.
Second visit they did nothing. - surprisingly this didn't fix the problem!
Third visit I called AppleCare to explain the problem. The issue and my concerns about the lack of service were escalated and the store was told to change the power supply which they did.
The store somehow managed to chip both sides of the pedestal and only when I pointed this out to them did they agree to replace the pedestal free of charge.

Best part? They're not even sure the power supply is causing the problem.

Also to those people who suggest recording when the issue happens, unless you set up a device to continuously record you can't capture the power off as there is no warning when it happens.

 

[Raist3001]

On my second trip to the apple atore, I was able to speak with a manager who now believes my logic board is the issue, so they will be replacing my logic board now. The video I took of my power down was very helpful according to the manager as I showed how the power button did not respond and I always needed to remove the power cable, wait 10 seconds and plug it back in. Since this also resets SMC, the manager suspects the logic board.
Crossing my fingers that this resolves the issue.

 

[Raist3001]

Went to pick up my iMac this past Friday. Didn't even get to turn on the machine as I noticed right away that my base was completely damaged. Dented on the sides, scratched, and it had pit marks on the flat base. I asked them to confirm that this was my base, and they said yes as the serial number under the base matched. I refused to take delivery of the machine, and the manager agreed to replace the base. So I'll need to wait yet another 5 days.

 

[iGeek2014]

It looks like there are quite a few of us experiencing this problem.

I purchased my Retina 5K iMac nearly two years ago second hand via eBay (UK) and for a long time it was absolutely fine.

Then it just started shutting down randomly. I ran a program called Etrecheck and the error code was '0'-unexpected shut down.

So I went to Apple, they've replaced the power supply unit and it still did it. Took it back, they restored the machine as new, and you've guessed it-it still does it.

Am taking it back again Tuesday evening and am in two minds to cut my losses and leave it there!

 

[Raist3001]

So it's been about 2 weeks now with my iMac and I have not had any shut downs. The last repair was a replacement logic board. Hopefully this has resoled the shutdown issue.

 

[Raist3001]

I spoke too soon. This morning my iMac again powered off. I took multiple video of this issue again before calling apple. I spoke with a high level adviser and explained that after having my power supply replaced, my display replaced, and my logic board replaced, I was not going to lug my iMac back into the apple store for anything less than a replacement. After he looked into my case, he agreed to a full replacement. Although apple's customer support is top notch, this is the 2nd iMac I have had with major issues.