iMac screen goes black, but system runs fine in background

Just started happening, and repeating more an more. Screen goes black (as if in power save mode), however system continues to run in background. To test this, I carried on typing and email, when I used the power button to put to sleep, then again to wake, all typing is there. This proves it is only the display going off. Any idea what is going on here - I've viewed old discussions, and others have similar issues but no solutions out there!

iMac, OS X Mavericks (10.9)

Posted on Nov 18, 2013 5:52 AM

Top-ranking reply

Andyjefferson

Level 1

4 points

Posted on Nov 26, 2017 10:48 AM

Experienced this "black" screen problem on my late 2009 iMac. It started a couple of months before it was booked in to have an SSD drive fitted. It happen twice a day initially, but by the time it was taken away to have the new hard drive fitted it was every ten minutes or so. During the SSD install it also had its logic board replaced due to faulty connector and upon return the machine is so much faster, but the black screen problem is still there. Done the PRAM resets and the other one and turned down the screen brightness ( which helps prolong the cut out time but still not a permanent solution). Tried fan speed software, but no better.

Decided this morning to look at energy saver settings and discovered they were set at 5 mins for display and computer sleep. I increased them to 1 hour, ignoring the warning about being more costly to run and also wearing out the display and drive sooner as I wanted the thing to work!!! and voila the black screen has vanished. I've even turned the brightness back up to full which previously seems to crash the screen to black and no problem.

So don't spend money on software, or hardware try this simple adjustment of your "sleep" settings in System Preferences - Energy Saver first and see if it that resolves it for you. I assume an IOS software update must have altered these settings at some point as Ive never been into Energy Saver before

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150 replies

Jul 19, 2017 4:20 PM in response to wildkarde

Back on June 26 Apple store wanted to try a software solution, ie., reinstalling Sierra. It didn't work. They said next step is to replace display. I didn't think it was worth it. I ordered a new iMac—the 3.5 GHz. They refunded all the payments I made for repair. New computer is nice and fast.

Aug 24, 2017 6:31 AM in response to PhilipAnthony

OK, so there seem to be several causes of this similar problem from reading the replies here. Here is another cause!

My iMac 27 Mid-2011 has had this problem for a couple of months and I have been SO frustrated with it. I use my iMac for Photoshop and Lightroom in my studio and alongside it I have a Windows 10 machine for bookings, email, general browsing, etc. I just find it easier with dedicated machines. The iMac screen would go back at regular intervals and sometimes would only stay awake for a few seconds before going black again. I figured out that if I gave it the Cmd, Alt, Eject to actually put it to sleep, then I could wake it up, but trying to wake it up without first putting it to sleep, just didn't work.

I also noticed that my Windows machine was intermittently having issues with response to the keyboard and mouse. They were around 20" away from the machine and moving them closer seemed to work mostly, but sometimes it didn't. More frustrations! I then started wondering if with both machines running Bluetooth keyboards and mice it was interference. Switching off the Windows machine didn't solve the issue, but then the penny dropped. Mobile phones! I have two mobiles in my pocket. An iPhone 6S for personal use and a Samsung Galaxy Edge 6+ for business use. Both had Bluetooth switched on. I disabled Bluetooth on both mobiles and Hey Presto! Problems with both machines solved.

rkaufmann87

Level 10

148,500 points

Nov 18, 2013 6:10 AM in response to PhilipAnthony

Try doing 2-3 SMC resets and see if that changes the behavior. Normally you do not need to use the power button to put the machine to sleep if you set up the timer to your liking in System Preferences - Energy Saver. If you have not done a SMC reset before please click Intel iMac SMC and PRAM resets for instructions.

Nov 18, 2013 7:05 AM in response to rkaufmann87

I've tried this 3 times, and no change. Also did the PRAM reset whilst at it, no change. I have hot corners switched off, switched off all powr save (although this happens whilst typing, but just in case). The system runs fine in the background, it seems that just the monitor/screen goes off. Are there settings for cooling fans or similar that could cause this? I've even turned my brightness down to avoid overheating, still no change. Never had this until during the last week, and it is occuring more often. As I type this, the screen has gone black - I continue typing, and will use the power button to put to sleep and again to wake and (hopefully) this typing is there ... yes it is! Confused!

rkaufmann87

Level 10

148,500 points

Nov 18, 2013 7:17 AM in response to PhilipAnthony

If you only did 1 PRAM reset please do 2 more. You can also restart in safe mode, this will clear some caches. It is possible 1 or more us corrupt. Operate in safe mode to see if the problem still occurs. To restart in safe mode when your hear the start-up tone hold down the shift key until a progress bar appears.

Nov 18, 2013 8:19 AM in response to rkaufmann87

PRAM done 2 more times - still went black after a minute or so. Started in safe mode (to be sure, after progress bar it needed me to sign in as the user again) - still going black on me (even as I type now). It is strange that everything but the screen works fine, I'm guessing it is a heat/fan issue, although it is cold here and the machine does not feel hot at all.

rkaufmann87

Level 10

148,500 points

Nov 18, 2013 8:36 AM in response to PhilipAnthony

Philip,

If you suspect a temp or fan issue I'd recommend two things. First is monitor the temp by installing iStat Pro and post the temps your machine is showing.

For the fan, if you suspect a fan or sensor has failed then run Apple Hardware Test in Extended Mode 2-3 times back to back. If any errors occur then it has confirmed you have a hardware issue and need to take your iMac in for repair. I don't have instructions for AHT but here is Apple's link:

http://support.apple.com/kb/ht1509

Nov 19, 2013 1:58 AM in response to rkaufmann87

Thanks for the advice - I have run Apple Hardware Test and it found no issues. My system will not allow iStat Pro as it does not recognise the author. I seem to have solved temporarily by reducing the screen brightness to below 50% - not ideal, but at least seems to stop the black screen issue - I'll keep you posted.

rkaufmann87

Level 10

148,500 points

Nov 19, 2013 6:01 AM in response to PhilipAnthony

Did you run AHT 3X in Extended Mode back to back?

Nov 19, 2013 11:42 AM in response to rkaufmann87

Yes - AHT 3X in extended mode back to back - no issues found. The second I restarted, and turned the brightness up to 80% it blacked out within a minute. Put to sleep and woke up using the power button and turned the brightness back down to around 30-40%, and it is staying on fine. So, through trial and error, it seems to not like the brightness too high, even though it has been at that level with no issues for a year/18 months. I'll just have to get used to working with less brightness I guess!

Thanks for all your help - at least this has lead me to the current position where I can at least use the **** thing without the screen going off every few minutes. Apple need to take note, and look into this, as something has obviously gone wrong.

Nov 26, 2013 2:35 PM in response to PhilipAnthony

my one year old 27" iMac randomly goes black screen at least once a day..... I can hear itunes still playing music and machine running

nothing awakes screen besides hard power button a few times or turning off surge...

have any of you determined wheter a Graphics Card issue versus a software issue?

thanks,

Nov 26, 2013 2:59 PM in response to rob kaplan

Rob,

After much trial and error, all I have done is reduce the brightness of the screen - no black screen issues in the last week since doing this. I think that it is something to do with overheating, although diagnostics found nothing wrong. If the machine is running fine in the background, it is only the screen that has gone off - try reducing the brightness and see if this works for you as it did for me. Not very technical, but if it works ... ! Good luck.

sureguru

Level 1

7 points

Dec 22, 2013 3:07 PM in response to PhilipAnthony

Had this problem crop up in my 2008 iMac over last couple of months. Tried lowering the screen brightness, SMC reset etc.. in vain. It got so bad that it would only turn on every 3-4 days and would stay on for 10mins and then black again.

Took it to the Genius bar, new graphics card.. (parts + labor = $180), now 2 days later running strong.

Here's the line item from the repair. Add $39 for labor.

661-4664

Card, Video, NVIDIA GeForce 8800 GS

$ 131.82

Hope that helps!

Feb 22, 2014 8:44 PM in response to PhilipAnthony

My iMac was doing the black out screen too. I read through ALL of the posts on this discussion.

Here was my solution:

> Disk Utility Repair. Twice.

> Turned screen brightness down, but not to 50% like other suggested. Just a bit lower than I've had it.

> I did notice that my computer was getting hot. By touch. I have iStat widget. My CPU temperature was reading 52˚C - 58˚C ... that's hot. My computer is well-ventilated and exhausts are clear from obstructions.

>SMC reset. Three Times. Let the iMac cool off for a good 4 hours.

After this. My iMac worked without a "black out" but only for about an hour. Then it happened repeatedly.

I did and Apple Hardware Test. 2 times in "Extended Mode". Recieved two seperate errors. One of those errors I looked up was about a "Fan faiing"

I downloaded and install SMC Fan Control. I set up 3 custom fan speed presets. Watched the temperature closely while I worked normally.

Video work with FCPX. Multiple windows open with Safari, Calendar App, Mail App, some finder windows. I also started to use Photoshop and Illustrator.

The temperature did start going up. I made sure that I balanced the SMC Fan Control to keep the temp under 50˚C.

3 days now. Hard working computer. Backups going, multiple drives connected. Applications and video and processor intensive work.

NOT ONE black out since I did the Apple Hardware Test and intalled SMC Fan Control.

Will post if a change happens. So far, I'm not seeing the need for an Apple Genius Bar visit. *fingers crossed*

Mar 25, 2014 7:15 AM in response to PhilipAnthony

Hey Everyone -

I've been reading these forums for a while, having the same issues as everyone else, off and on for the past year or so. (I posted here and got no real response, but to bring it into the Apple store - https://discussions.apple.com/thread/5818360)

I did all the tests again last night, ran a hardware test (no issues were found), PRAM, blew out the vents to get rid of dust, added the app for fan control. Turned the baby on again, and it still went black on me.

Found that the only way to get the screen back on again was the short cut shift+control+eject and then wiggle my mouse again to wake it up. But it turns off again after 30 seconds or so. So it's not really a heat issue. And I feel like it comes and goes. I went two months without it really doing this, and then it started up again.

I'm noticing the screen gets a little jumpy when I have the brightness at a low, which I thought would do the trick, and surprise, it doesn't. So now I have it really high, and my eyes are buring from their sockets!

I'm not on Apple care anymore, and don't really want to fork out the money to get it fixed, cause I want to invest in a MacBook Pro. But my iMac, other than the screen sucking, works like how an Apple "should be" working.

I was curious if purchasing a monitor in general (HP or Dell), and hooking it up to the iMac and sharing the screen would be a good second rate option (since it seems like it's the screen that has the issue and not the computer in general), and if anyone else has done this? I know it's kind of a second rate option, but I'd love to hear what people's advice on this would be.

On and on!!!

Tara

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iMac screen goes black, but system runs fine in background