27 iMac (2012) crashes and requires smc reset to turn on

Hi Beolion73,

Did you only replaced the PSU (which brand?) or more parts?

Got he same problem with my iMac Late 2012. Have brought my Mac in September 2016 in service, but they didn't found any problem. After that, he worked for about a week or 5 without any problem. Then it started again. Last days it shuts down more times a day.

I also read posts within this tread, that the PSU was not the solution. I don't want to replace half an iMac with new parts which not resolve the problem.

I love Apple products, but I think the next Apple product I will buy at a Apple Reseller who offers 3 years standard warranty en sell it some months before the warranty ends.

If you have the SAME problem as described in this thread...

go for sure with PSU..

search LiteOn Brand...

Don´t waste time looking for anything else...

Those shuts downs happen because there is a bad capacitor on PSU.

For me it came to a point where I just had too many shutdowns.

I replaced the Delta psu with the Liteon. Bought on eBay for 50 EUR. Plus I bought the parts from ifixit to take it apart.

And it is still working fine for me.

I am still sad to hear all the stories but I don't believe that Apple will ever recognise this particular fault.

Especially since the technicians are saying they never heard about this fault. Shocking.

Hi all

Just an update, after around 2 months now with the new PSU I have not had a random shutdown, yet :-)

I have also tried to leave the iMac on for several days playing music which went fine, and I do not have to unplug the computer from the power outlet.

All in all, still going strong, crossing my fingers.

Last note, the screen seems a bit brighter than before, like others mentioned.

I had my PSU replaced back in May 2016 and since some weeks the shutdowns have re-appeared, exactly like they did the first time around November 2015. Once my iMac is turned on for too long (say a day, in sleep mode) and I work a few hours, it crashes. Unplugging for 10-15 minutes makes it come back to life again.

Unfortunately, I am out of Apple Care now, so I hope someone has any suggestion what can be my best next step. Is there in the meanwhile any update from Apple that this is a real issue impacting certain builds?

My one-month old 27" Retina (Late 2015 model) is doing the hard shutdown thing, with an SMC reset required to start again. Clicking around in Safari will do it, 100% repeatable, just a question of whether it takes five hyperlinks or 50. No way to predict when, but it WILL happen. Does it on all user profiles, in Safe Mode, even on a clean install in a new disk partition. This jazz started a few days ago and is quite infuriating.

It's going back in to Apple tomorrow, after blowing much of the weekend doing tech support chats and going through the many attempted remedies.

Tom

So after a week at Apple, nothing found. The store tech actually had a couple of interesting ideas that I had not explored. He said the SMC can act as a fuse if it senses irregularities through the power input or Ethernet port, and may shut it down as a protective action.

Trying a couple different things now, like a new surge suppressor (just in case, since it was several years old) and connecting through wireless instead of Ethernet. Thus far the problem has not recurred. If it works for a few weeks in this config, will try using Ethernet again to see what happens.

Tom

I've. Even dealing with this too. After two weeks analysis and effort by AppleCare & Genius Bar at local store they are giving g me a new iMac. Apparently Apple admits an issue in the operating system. They are working on a fix but. It there yet.

Just cut the power supply and wait for at least 20mins. After that replug and the Mac should start again.

The key at my site was to switch off the Mac overnight and cut the powerplug completely. That still works fine, no shutdowns since months.

I have the exact same problem. I just retrieved it from the Apple Store. The had replaced my previous hard drive because of the same problem, because my hard drive became fried because of this.

Do I need a new power supply?

— MacGroupie

Hi,

iMac Late 2012, with shut down issue happening randomly, but at least one time per day (and often more).

I had the Delta Power Supply, replaced with the LiteOn Power supply.

No more issue since 2weeks.

Thx for your help guys !

OK, so after Apple replaced the hard drive, which had apparently been fried, I reinstalled all of my software and documents. Thank god for Time Machine.

A few days later it all started again. Imagine my frustration. About four days of work lost, but at least I had my backup files.

Took it back to the Apple Store. They replaced the power supply and the logic board. Less than 24 hours later, so far, so good.

Oh, one more thing. When I brought my machine back to the Apple Store, I told the Assistant Store Manager (we'll just call her "A"), that this was a known problem all over the Apple Discussion boards, and why had they not replaced the power supply in the first place, she said that the techs were not trained to keep up with "Social Media."

So, I guess Apple Discussions is "Social Media."

True story. Not fake news.

Just wanted to give an update as well. I installed the new LiteON PSU and have had no issues for the last 4 weeks. My iMac has been on the entire time and only gone to sleep when not in use. It seems that the problem was 100% the Delta PSU.

For those intimidated by replacing the PSU, it is not a difficult process and only takes about an hour. There are great videos by both OWC and iFixit. If you decide to replace the PSU I would also recommend replacing the HDD with a SSD too. The new SSD has made my 2012 iMac run like a brand new machine (probably even faster than some of the current HDD versions).

Like others on posts found all over by google searches I have this indiscriminate shutting down.

My iMac is a late 2012 A1419 27" i7 3.4MHz with 31GB ram and a 500Gb SSD and 3 TB Seagate HDD.

After trying all the usual tricks (resetting the SMC, PRAM, clean caches etc) I came to the conclusion, independently, that it was the power supply that was the cause of the issue. I am most reluctant to let so-called Apple techies touch the machine. They would just tell me what I already know ... "the ram is non-Apple, the SSD is non-Apple, the HDD is non-Apple" .. you get the picture.

I have ordered a LiteOn power supply from the UK which is a lot more expensive to ship to Australia than the books I purchase from the Book Depository.

I will replace the PSU and the broken hinge (another crappy Apple issue) and a faulty HDD data cable at the same time. These tapered edge iMacs are a bit easier to work on than the older thicker edge iMacs thankfully.