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

There's no one who want too replace my PSU. I got a workaround to unplug every evening the power cord. Only plug it in when I use my Mac. Last days I get a kernel panic when I'm booting up the system. I must shutdown the iMac en unplug the power cord for several minutes. Can some one see what's the problem? Is it related to the fault PSU?

So sorry to all whom are still having this problem, after I changed out my PSU in October of 2016, it has been rock solid! It saddens me that Apple will not fess up to this, THEIR problem foisted upon their loyal customers.

This is the screen what appears when I'm booting up the system. Does anyone know what the problem is? I also have a 27 inch iMac, late 2012 (other specs: 3,4 GHz Intel Core i7, 32GB 1600 MHz DDR3, NVIDIA GeForce GTX 680MX 2048MB). Just cut the power supply (for three hours) didn't work out for me, I get the same screen and the Mac didn't booth up the system.

Jul 5, 2017 9:19 PM Re: 27 iMac (2012) crashes and requires smc reset to turn onin response to Lagoiski

I also have this problem.

Is there anyone who has installed a LiteOn power supply who is still experiencing this issue?

Hi Bill,

well, almost 9 months after my PSU replacement to the Lite-on, and the system is still running. I can't even remember when I last made a full shot down, so it's working as it should.

I think the replacement was a bit complicated (first time, and thanks fr Youtube), but for a authorised repair person, I assume the PSU repair is straight forward and won't take long.

Leo

(Excuse me for my weird English language)

My iMac 27", (Late 2012 - 3.4GHz i7 - 28GB DDR3 - NVIDIA GeForce GTX 680MX, cost a fortune) has the exact same problem. Thank you all for the options mentioned in this thread.

We've read the 33 pages with comments and we'll try out two things:

#1 test: From now on, every time I shut down my mac, I will also shut down the power supply socket.

if that doesn't work:

#2 test: I'll ask a smart fellow to replace the 'Delta PS' with a 'LiteOn PS'.

I'll keep you updated.

All the best of luck for the new year 2017.

Greetings from the Netherlands, Linda

A notice, shutdowns are not good for logic board, so, what I do to take care of it .. is to use the computer about 1 hour, then power off it manually (as commonly you do), disconnect power supply cord, wait 1 hour and start again.... at least with this way, you will be sure that logic board keeps fine.

Hi all

Now it was my time to replace the PSU of my iMac.

First of all, the system has only been running for a couple of hours, have to wait to see if the new PSU solved my shut down problem. However, the old PSU was a Delta, the new one is a Lite-on.

I ordered the Lite-on from China.

Here are my experiences doing the replacement. First of all, it went relatively smooth, and I followed the guide from iFixit:

https://www.ifixit.com/Guide/iMac+Intel+27-Inch+EMC+2546+Power+Supply+Replacemen t/15722

I did also order the replacement parts and the adhesive tape required.

Removing the adhesive tape the screen went easier as expected using the roller.

I was a bit nervous detaching the cables as I was not aware how hard I can hold the cables, but it all went fine. The only tricky part was to disconnect the power supply control cable from the power supply (step 34 in the guide), that took a bit of time. Taking out the PSU and putting in the new was straight forward.

Unfortunately, the connector on the new PSU was bend a bit and I could not put the cable back on (step 34) straight away, I had to tweak a bit here and there.

Before attaching the screen again with the adhesive tape I attached the screen cables to the iMac and made a quite restart of the machine to verify that the PSU worked. After this, the screen was put back again with the adhesive tape.

Final remark, we were 2 to make repair, especially convenient when handling the screen, and I strongly recommend being 2 persons to perform the operation.

I will post again in a few weeks and let you know if the replacement fixed my random shutdown issue.

out of warranty 27-inch late 2012 imac heading to genius bar tomorrow. i called apple and spoke with a very nice person and I explained that I was aware I was no longer under applecare but that I had noticed that number of people with nearly identical models having the same issues. she set the appointment up for me and I am hoping I will be able to get the person at the apple store to understand that this should not be happening and regardless of warranty apple should fix this. I am typing as fast as I can expecting it to shutdown any minute. wish me luck and I will try and report back. good luck everyone.

THe iMac is currently at the Apple Store. I took my iPad in with this page up but the tech was not interested in it. I explained in detail that many people are experiencing the exact same problem and have had components replaced but that did not resolve the issue. He said they would keep it 3-5 days and get back with ,e. If they find any hardware problems they will give me a quote. I swear it's like apple isn't even listening. This is of no fault of mine and in its current state it is of no use. I was really looking forward to getting a macbook this year but it seems the quality of apple is taking a turn for the worse. I will keep you all posted.

Sad to read that, .. but keep in mind something, YOU are the customer, you will pay the service,, you MUST to claim your rights, they MUST to listen to you, is really blind that they won't to see this large thread on the official Apple site....

Here is how to reproduce the problem: Just keep the imac power off and connected to power supply for a couple of hours until the bad capacitor of your PSU get charged, turn on the iMac (at the store).. and wait with them there until it shuts down.. then, lets see what they can say...

Don't allow they ask you for change the Logic Board... you need to tell them to change the PSU first.. and try. you know.. everything you do in an Apple Store is $$..

Good luck

Just an update. My iMac is still running strong after the psu replacement. I just had it running continuously for the last 24 hours (playing music), no shut down until now.

And the new psu is the Liteon brand.

I don't believe that we ever will see any official acknowledgement of this issue from Apple, unfortunately.

as a customer of apple with many apple products under my belt I have never run into anything like this. sure there was the resent battery replacement program for the iPhone 6s and there was a hard drive replacement on one of my imacs before but those were all acknowledged by apple. I am well aware that apple is most likely going to claim I need x/y or z replaced at a certain cost. that leaves me with either paying for it and hoping the problem is solved or not paying and just throwing away the mac. Of course if I go with the latter i will be left with deciding whether or not I trust in apple enough to purchase a new mac. We shall see what they decide to do.

Given the randomness of the shutdowns I am guessing everyone may experience a different length of needing to leave it unplugged.

Also I will be more than happy if apple truly has found the reason for my shutdowns but since it seemed to fall in line with this thread and a majority of late 2012 iMacs I assumed we all shared the same problem.

I could be wrong. It would. It be the first time.

I started with the same issues. Apple replaced the Logic Board and I used the iMac twice and it was good (2013 model) - today, it won't even start. Pushing the power button does nothing. Doing an SMC does nothing - and then out of the blue it started up by itself!!!

I ran tests etc - no issues, and let it just sit doing nothing - down it went fast and pressing the power button gets no response at all until the iMac feels like it.

Honestly, I feel very taken in by this model and am feared of ever getting another iMac again. I don't even want this one any more. Typing from the dark side 😟!

Note that Safari, Flash or any other browser use will reduce the alive time of your iMac....

today, I played OpenEmu only for about 9 hours without shutdown... disabling wifi and internet...

wifi and internet use a lot of power.