iMAC 27" random screen blackout

Hi there,

This seems like a really frustrating problem. Be nice on the phone, and of course they will replace the computer for you. Really sorry to see you have such a difficult time with this computer, you're right that it may well be a graphics/video problem.

I reccomend doing the following when your screen is blacked out:

Create a System Diagnostic report. You can do this using the special key chord Control-Option-Command-Shift-Period. Press these keys all at once when your computer is in the problematic state.

It may take a few moments for the report to generate. Once data for the report has been gathered a Finder window will open to reveal the report file. It will be named something like sysdiagnose_Aug.09.2011_08-47-27.tar.gz.

If your computer has become completely unresponsive you will need to reboot your system. Once your computer has restarted locate the diagnostic file. You can do so as follows:

- use cmd-shift-G in the Finder to bring up the "Go to Folder..." dialog

- enter /var/tmp as the path for the folder you want

- locate the sysdiagnose file in the resulting Finder window

Give an Apple Genius this file, and let them study it.

Nathan

You are not addressing Apple here, they do not read nor participate in these forums. If you are in the USA please call 800-767-2775. This is a customer service number, not tech support it's more of a customer advocate phone number. Be polite, organized, and make your request. They will probably send you back to service but if you are persistent you may get the machine replaced.While the machine is still under it's 1 year warrant get AppleCare to extend the warranty to 3 years.

Hi,

I just dropped of my 27" iMac for the exact same problem. Bought mine in Jan `12. Did you get your resolved?

Call Applecare and then asked to be transfered to Customer Relations. Tell them everything you've been to with your iMac. Be as detailed as possible.

We are having the same exact issue. Took it in to the Genius Bar on Friday and they ran diags for three days and found nothing wrong with the hardware....which makes believe it's a software bug. You are correct in that the system remains functional while the screen is blacked out. I have some remote destop software and can still access and use the iMac while the screen is blacked out. Also the fact that it didn't peek it's head while they ran diags would be a strong indicator that it's the OS that is the culprit. I just hope someone can identify a patch or an updated driver to prevent this from continuing.

Hi, I hope you find this information useful:

A few years ago, we purchased iMac 27" 11,3 (Mid-2010) (with i7 2.93Ghz, ATI 5750 1GB VidRam, etc.) for our offices and software development team. They were originally shipped with Snow Leopard and worked as expected and without any problems. However, a year later, we upgraded to Lion and all of machines immediately exhibited the same problem: the screen would go to sleep by itself and would require a hard reboot or sleep on/off. (Only the screen was asleep and the rest of the iMac continued to function; this was confirmed by screen sharing to the machine.)

Due to the severity and impact on our business, we immediately contacted Apple and their genius bar staff in New York/SoHo. They were unable to determine the root cause, so they replaced all of the logic boards, video cards, and screens, and got us back online asap. This resolved the problem, but we were curious to know why. After days of rigorous testing, we concluded that the issue is caused by a bug in MacOS. Specifically, faulty Kext files (Kernel Extension files extend the functionality of the MacOS Kernel) for the ATI drivers. So, why did the replacing the hardware work? We think that the Kext files that were released and distributed with Lion (and later MacOS versions) correctly supported the newer hardware revision of the replacement components, but not the older ones.

If you're experiencing this problem, short of replacing the components or waiting (for another 3+ years) for Apple to hopefully fix their OS software, you can lessen the effects and be able to recover faster by doing the following: (Please bear in mind that these are not permanent fixes.)

1. Turn on "Hot Corners" and assign one corner to "Put Display To Sleep". When your screen goes to sleep, move your mouse (which still works) to that assigned screen corner for a second, then move it again. This will wake your screen. You may have to do this a couple of times, but it's much faster than a hard reboot or a sleep on/off for your iMac.
2. Turn the brightness of your screen to a low setting (10%-15% of the total brightness).
3. Turn on screen sharing, so you have a last resort method of accessing the machine.

If you're not convinced that it's a MacOS software problem, then do what we did and see for yourself; install Windows 7, Windows 8, or Linux via Bootcamp or as the only OS on the iMac. Those operating systems and drivers worked flawlessly for us; the bug does not occur and the screen does not go to sleep, but if you dual boot and switch back to MacOS, the bug reappears because the iMac is loading faulty Apple MacOS software.

Good luck!

I've had the screen blank problem, took the IMac in twice, got home, still not fixed.

But they used their own keyboard in the shop and couldn't reproduce the problem. I switcheds keyboards and so far so good.

I'll keep folks updated. Don't get a new graphics card before you try a new keyboard.

Hey, thanks, I found my lost post. There are three similar threads. Guess the forum management doesn't merge them.

While your wife is using a different keyboard, is the other keyboard still in the vicinity? Try removing the batteries from your keyboard that came with your IMac and then using the other keyboard. My Mac keyboard doesn't have an off switch. When you depress the on button it only turns on if it is off, but it does not turn on and off. And two mice work at the same time on my computer so I assume the same ocurs with the keyboard.

In the shop, they use their own power cords, keyboard and mouse.

I don't think everyone is necessarily having the same problem, but so far with this other keyboard, I've gone 3 days, no blackouts. I can't say for sure this is the problem though I am going to take my keyboard into the store rather than using it again to see if the problem recurs.

A person in one of the other threads took his keyboard batteries out and has now gone 12 hours without a blackout.

But my problem manifest itself after I was home using the computer for a week or more. First time I took it in and got a new hard drive (which was failing and was on the recall list). A week or two at home and the black screen recurred.

Took it in again and they were unable to recreate the problem. They blamed it on software and reformatted the new hard drive 'again'. I reinstalled files but no aps.

Another week and it happened again. This time I tested the volume control and verified the computer was still on, only the screen was off. My son suggested testing the screen brightness control on the key board, which seemed to work. But then it dawned on me, you can turn the brightness all the way down and you have the symptom. And they use a different keyboard in the shop where the problem did not recur.

I switched keyboards with an old one I still had. It's been working since. I don't know. Could be the problem will recur in a week or two. OR, could be it is the keyboard. It would explain why the geniuses are not finding the problem.

Forgot to add, temperature did not affect my problem. I tested for that, hot and cold it still occurred.

I got the same Problem and I have always three Days no Problem. But it is bound to what I do. I can force this Screen Blackout with any embeddet Youtube Video. So it seems for me also a Solution to stay away from Youtube. But the Hot Corner Solution from "mwp13" works well. So it is not Random. It is bound to your Internet behavior.

And some additional Information: On my Macpro it comes with the last OSX Update. So Apple is highly involved.

I have it even more exact it is not Mavericks. Our beloved OSX is acquitted. This goes to the account of Adobe and Flash. It came with one of the Flash Updates. But with the latest update it seems to be then corrected again.

And yet I've done nothing with Flash whcih was not reinstalled after my second hard drive reformat yet the problem recurred.

And my MacBook which has the complete restore from Time Machine and would have had the problem Flash version but it has not had any problems. I enable flash to watch certain videos on the notebook, but keep it disabled in between. It was causing a screen crash or Net freeze which did not cause the computer to blank out.

I think I loaded an Adobe update since then but it would have been on the IMac as I didn't own the MacBook at the time.So the MacBook has whatever was on the IMac from Time Machine and that was the same when then problem occurred.

After the second reformat, the only apps I reloaded were Word and Scrivener. The blank screen returned.

I do think people are having different problems with the same symptoms.

Hello Girlsonboard. You have nothing done with the Browser? Embeddet Flash is on much Websides. I could trigger it with a Youtube Video. 10 Seconds Youtube and the Screen was black.

And also it dont happens on every System. This is bound to the graphics Card. So some have it some have it not. No Problem on my Macbook too. I have done the most recent Adobe Update and no Problem now.