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

Answering your question: "You have had the power supply component changed only and since then have seen once the issue, is it correct?"

The logic board was replaced first, but the issue was not solved. The power unit (661-7170) was the second component to be replaced (on November the 26th) and the issue has not been seen since then.

Thanks a lot for your quick answer Robert.

Just waiting a bit to get some one confirming the same behaviour, or on the contrary, indicating that it solved the problem only for a while (not that I am wishing it).

I have had a power supply replaced on mine. Engineer seemed pretty convinced this was the problem. It's only a been a couple of weeks but no shutdowns so far.

Thanks for the comment, crossing fingers for you.

Just to know, how would you qualify the frequency of shutdown you had, once in an hour like or once a day?

If left unplugged overnight I would get 2-3 hours. Then after the first switch off no more than 20-30 mins max.

Ok, nice to read again confirmation of the behaviour.

Hopefully, changing the power unit (661-7170) is a real solution.

And in the worst scenario, if it is some kind of component to change every one, two or three year, as pain-full as it is, it is almost an acceptable deal (less than a 100 euros or dollars).

Still, I am willing to wait just a little more in case one come with on contradictory case.

Thanks again.

Laurent.d awesome reply here well done just putting all the problems and "attempted" fixes listed on one post is great. So here is what I have discovered after hours of phone calls and reading on parts. Spoke with a local Mac guy not at Apple store today near home and right away he said he wouldn't even open the 2012 or newer machines as they are too tight and tough to work on and recommended I have Apple do it which again would be fine if I trusted it would fix it but as we all know probably won't. So after the 8 months of having the issue and ****** as can right now I've decided today I'm going to try and order a power supply and tear down this EXPENSIVE paper weight myself, which BTW was off again when I got home this evening.....10th time this week.

My applecare has expired and honestly for the cost of the logic board, power supply and Apples Guru pricing etc its probably cheaper to buy a new machine at this rate so I figure why not attempt this repair myself as machine is really not worth much at this point and I'm determined to figure out whats causing this. I've ordered the tape for screen replacement and tools and will get the part this week and try the power supply first. It will not be the SAME model/version thats in it as I feel like even the replacement parts are junk which also may be causing the issue so why not try something different. Either way guys I'm going to attempt this maybe next weekend and will let everyone know how it goes after. If not I'm at a lose with this and its just crazy to me that Apple doesn't see what is happening here and offering to at least figure it out for us as most of us would be happy to get it fixed and pay but would like to know whats causing it and see them back it up.

Laurent, as I had posted, Apple decided to go ahead and give me a new machine. A 2015 5K model. After almost a year of suffering, I'm relieved. After replacing the power supply, and the logic board, the problem kept resurfacing. So I don´t think it was worth for them to try and repair it over and over again.

I know you've posted this before but if you dont mind, what was the year of the iMac that got replaced? Mine's late-2012 and problem surfaced 1.5 years after purchasing. Also, do you have Apple Care/warranty when you brought this to Apple.

Unfortunately same issues here with a late 2012 27". Last July it started shutting off, I spent 2 months of phone calls, chats with support, took it into the store and left it twice before finally after two months they replaced the power supply last September. Now four months later it's doing the same thing again. My apple care runs out next month so I'm no pleased that I spend $2300 on something that will be worthless. This is our family computer so I'm not too excited about the idea of having to deal with issues over and over again for the next few years. Any idea if this is something that happens on the newer versions? Or anyone have experience with Mac mini. I'm hesitant to get another iMac now.

to Annecarter:

I do feel your pain here. Though, one positive point I can get is that you had the power supply changed and that provided you about 4 months free from any issue, is that correct? If so, it really sounds like this could be the source of the problem, but also that the power supply component is relatively unstable since it degrades so quickly.

Also, I remember thinking initially about getting a mini that would use the iMac as a slave for the screen, but I don't consider it as a solution anymore (shutdown would still happen as the iMac still runs in the background). Though, plugging the mini to a TV could be your solution, but it is out of this conversation scope.

to Joe5000:

Yep, I had understood you were 'lucky' to get a swap for a brand new one(not that you haven't suffer for it).

I was just wondering what was the ultimate argument that won over the heart of the Apple representative, and if you still were under the 1 year guarantee or the Apple care plan.

to FalseAlbie134:

So you are intending to change the power supply yourself, with another component than the one used by Apple for this iMac. I have to say I would not dare trying to do it myself, easy on a PC but totally a different story on those iMac.

How did you get the power supply unit, how is it different from the original one?

Did you get Apple to change your power supply once before, without success?

In any case, all the best to you if you are definitely proceeding to the change yourself, and keep us updated please ;-)

I am expecting a call from Apple today, and will provide feedback to you as to what is their take on changing the power supply while this one seems so moody.

So, as expected from talking to an advisor for 40 minutes, they can not do anything, only redirect you to the Apple Store (my only success was to get the advisor to sympathise with me), and this regardless of how many people are affected.

I guess it leaves me with no choice but to go visit the Apple Store, explain again the issue, and stress on the fact that power supply could be the cause.

I shall also give a link to this discussion.

Given that nothing would be found and that we would opted this time to get the power supply replaced (paying for it), I was wondering if there is any kind of guaranty on the new component, so I looked at the retail and repair terms and conditions and I understood that there would be a 90 day warranty, do you agree with my reading of point number 5 (french version is similar)? If so, that would give around 3 months time where if the issue resurface, the next repair is free, wouldn't it?

Same as you: Late 2012 with Apple Care which expires mid February 2016.

Not necessarily. It took mine exactly 4 months after the power supply was replaced to start happening again.

So I noticed that on the prior model (mid 2011 - Mid 2012) on the 27" there was an issue with the graphics card that eventually resulted in a Apple wide replacement program. Some friends have suggested that could be the problem with the late 2012 model as well. Thoughts?