Late 2012 iMac locking on Sleep

I am having what seems to be same issue.

Late-2012 27" iMac i5, 3 TB, Fusion Drive, stock Apple 8 GB RAM, wired keyboard, wireless mouse.

Normally I logout when leaving the Mac; no problems logging in and continuing. On only two occasions since purchase/pick-up in April 2013, I used the menu command to put it to sleep. After the first time, it would not wake up. I don't recall exactly what I did... but I got it to wake up. Three nights ago, I commanded it to sleep and now it seems to be dead: no power from USB to iPhone, clicking mouse or keyboard or pressing power button does nothing, no sounds (e.g. fans). Dead.

I unplugged all peripherals. I unplugged power (checked source which is good). I have tried re-plugging power after leaving unplugged several times, after 30 seconds and after as long as overnight (replugging, clicking keys repeatedly, pressing power button). It seems to be dead.

I *do* have a newer technology powered USB hub which, IIRC, has been in use from almost the beginning after purchasing the iMac. Maybe that is an issue...?

I'm assuming at this point, I am in store for making the trek for a Genius consultation. Maybe one of them can do some magical CPR and bring this machine back...? Thankfully, I have kept my old, original Intel iMac so I have something to work on. After several Macs since my first (512ke) in 1985, this is the first real problem I have had. But that doesn't make it easy to deal with.

Late 2012 27" iMac i5, 1TB Fusion Drive, 16GB RAM, wireless keyboard and mouse.

I experienced these same troubles when I bought my iMac. I finally solved them once and forever when I removed power form the USB hubs (both 2.0 and 3.0). I now use them without power and have not had a "not wake up from sleep" episode again.

Even more I can reproduce the problem if I power the USB hubs so definitely powered USB hubs is the cause for me.

Imac Late 2012 27inch i7 GTX680mx 1TB fusion drive

I have a random issue after sleeping mode.

The Imac does not come back, so what I have to do is to unplug it and plug it back again. It happens from the beginning. I have asked for help on the phone, and three times on the store. But they can´t find where the problem is. They´ve restore the system, unplugged a kingstom RAM which I installed, and restored again; but no success. After evry two weeks or so it happens again.

It is really annoying when you rely in a brand like Apple and they can´t even find where the problem is. As I have found this forum I feel less loney with this issue, but it´s no fun to buy a very expensive computer and not being able to use it for professional purposes.

I am going to get the computer from the genius bar for the third time in month and a half, I hope the issue will be repaired, othewise I will think twice before I buy another Mac for pro-video purposes.

Pedro in my case it was a USB derived problem with a device that I was using with no issues on my older iMac.

Have you checked if you can reproduce the problem with all your USB devices ( except mouse and keyboard) disconnected?

Please check this for a couple days so you can isolate the problem. If your computer behaves OK with your USB devices disconnected then you know is a USB derived problem. Then attach your USB devices one by one and test your sistem for a couple days until you experience the problem again and then try change that individual device.

Hope it helps

I´ll try that and see what happens.

If that´s the problem I´ll post it so that everyone can get help.

But the only thing I´ve got connected to de usb ports is a wireless wacom kit to a tablet, and I would say that it has not always been connected when the issue happens.

Thanks for your response!

Ok, today I´ve had the same issue again and it´s been after a blackout. I have the iMac plugged in to a SAI, so when a blackout happens and the iMac is not sleeping there is no problem, but if it is sleeping there is no way to make it work agains unless I unplug it and plug it back again.

I still do not know if this is a normal behavior or not, but it makes more sense now. I have an appointment to talk to an expert, so when I´ll get more information I´ll post it.

I have the same issue. I have trawled through everything written on this that goggle identifies without a single solution. I have tried everything suggested in multiple posts on similar topics without success I have tried everything suggested by the geniuses at apple. It seems it is a hardware issue. My recommendation is to immediately take to It back to apple as it could and probably is a hardware issue that only gets worse and worse over time. Reinstalling OS, SMC and PRAM issues, third party software and peripherals hubs etc are probably not the issue. After reading multiple post the problem only reappears and becomes more frequent which indicates to me that it is hardware. Why does anyone need to prove to an apple genius it is hardware let them prove to you it is not hardware. Don't waste your time especially if it randomly occurs!

Late-2012 27" iMac i5, 3 TB, Fusion Drive, stock Apple 8 GB RAM, wired keyboard, wireless mouse.

After my post of 08-16-2013, I took the iMac to the Apple store. Genius initially thought it might be stuck in what he called (IIRC) "deep sleep" but he was unable to locate or fix the issue so I left it. They had it for two weeks and even after forwarding all their diagnostic notes to higher-up tech people, no solution. So, I got a new iMac. Apparently Apple's policy is, if a customer goes without their device for 14 days, they get a replacement.

I have not used my powered USB hub on the replacement as I am afraid that would cause the same thing to happen again. And I'll probably never use the command feature to put it to sleep, just to be safe. But otherwise, very happy with the outcome and Apple's handling of it.

I am glad you got it replaced. I likewise am having it repaired or replaced. In Australia statutory warranties can last 2 years. It is unfortunate you are not using your USB device though. I hope people do not waste time and effort trying to resolve what should be resolved by apple. Bite the bullet, back up your data and head to apple. They have great customer support so take advantage of it.

Definitely, the issue has to do with the combination of the external power source and the computer. I hope this post helps to people qith the smae problem.

Thnaks!