Stepppy

Q: iMac 27" Screen goes black repeatedly, but then settles for a while?

Hi

 

I have searched and found numerous posts which sound similar to mine, but none seem to be so bad. Its a long post, but I want to make I have given as much information as possible

 

My Energy Saver settings are default 10 minutes for display & computer sleep, but I always find the screen will go black for a period of time before it goes to sleep and normally when I go back to it I press the keyboard or trackpad and the screen comes back to life. However, this time it didn't. I tried everything I could, but in the end I had to hold down the power button until it turned off. Once I restarted it was ok again.

 

I didn't think much of it, but I researched and found lots of people had similar issues, but were mainly on MacBooks. I did find a post where people had set a hot corner to turn the display off, so if the problem happened again they went into the hot corner and then came out of it and the display would come back on. This stops the need for having to force the computer off. I set up a hot corner, just in case it happened to me again and I'm glad I did.

 

In the last couple of weeks the display has been going off at random whilst I have been using it, nothing graphic intensive, just web browsing. Going into my hot corner and coming out of it bought the display back to life thankfully. It was yesterday that things got really bad, to the point that the display was staying on for about 3-4 seconds before going off. Again, going in & out of the hot corner worked, but then it didn't. Initially I thought it maybe some kind of software issue, but when I restarted the grey screen would only show for about 3 seconds and then go black, so I didn't even see the Apple logo. I could hear everything start and it would pause at the logon screen. Going in and out of the hot corner several times finally gave me enough time to login before it went off again.

 

After logging in I got it back only for it to go off again. I tired everything I could to get the screen to come back to life but it didn't want to play. All the time everything was working on the iMac, it wasn't frozen and didn't crash, just no display. I did some research on my iPad and this seems to be a common problem in one form or another, but no one that I could see had it as bad as mine. Some people were saying it was software related, other that it was logic boards, but as I said earlier I think the majority of posts related to MacBooks and not iMacs.

 

This was my first Apple purchase and I feel like a fish out of water as I have always had PC's before and if they went wrong I just fixed it myself, but I don't think this is going to be the case this time.

 

Very late last night I managed to get the display on long enough to run iBoostUp and let it give everything a spring clean. It kept going off whilst it was doing its things, but I did manage to get the display back for long enough to shut it down fully and I left it unplugged over night.

 

It started working fine this morning, but after more reading I have reset SMC and PRAM as that advice seems to be given a lot when people are having problems.

 

I have been using it for roughly a couple of hours and it has just this second gone off for the first time. I did my hot corner trick to get it back, then about 3 sends it went again. Now it seems to be ok again. The only program running is Safari.

 

I am running Lion 10.7.4 with all updates done and I am not running Boot camp for Windows 7 I thought about doing a clean install, but I am not convinced that is going to work and don't want to go through all the hassle of that only to find it still does it! Taking it to Apple worries me, because as its intermittent it may not do it whilst they have it and also I am worried about all my personal data I have on it. Would they wipe the hard drive and would they access my files? I have never had this worry before as any PC problems I just switched problem items myself. The machine will be a year old in a couple of months and I am already thinking the AppleCare Protection Plus is a very good deal and a must have at £139 for two extra years warranty.

 

Any suggestions great fully received.

 

Thank you.

iMac (27-inch Mid 2011), Mac OS X (10.7.4), 12GB RAM 1TB, AMD Radeon HD 6970M

Posted on Jun 24, 2012 5:44 AM

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Q: iMac 27" Screen goes black repeatedly, but then settles for a while?

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  • by Adamglittle,

    Adamglittle Adamglittle Mar 20, 2014 2:20 AM in response to AlexJ2013
    Level 1 (0 points)
    Mar 20, 2014 2:20 AM in response to AlexJ2013

    Thank you AlexJ2013. I have reduced my brightness and -I think- that is helping. Thank you :-)

  • by MRO67,

    MRO67 MRO67 Mar 20, 2014 2:25 AM in response to Stepppy
    Level 1 (0 points)
    Mar 20, 2014 2:25 AM in response to Stepppy

    I have the same issue since a couple of months (Late 2009 iMac 27"). I have just also set the brightness to a minimum and the screens keeps working. Not the most optimal way of working but at least it's working. Hopefully Apple starts looking into this issue.

  • by richardaustin,

    richardaustin richardaustin Mar 25, 2014 10:50 PM in response to MRO67
    Level 1 (10 points)
    Mar 25, 2014 10:50 PM in response to MRO67

    Has anyone tried disabling the Energy Saving settings especially for display?

     

    My screen was going black every minute or two this morning. I managed to bring it back up by establishing a screen share with my MacBook Pro. As we know, active screen sharing forces the display to stay on through the duration of the sharing session. The display stayed on until I disconnected the screen sharing session, and then almost immediately it went black again.

     

    The ctl + shift + eject shortcut brought the display back for a minute or less. But it kept going off repeatedly every minute. Connecting the MacBook Pro through screen sharing kept the screen on again until I disconnected. I then wondered if something wacky might be happening with Energy Saving settings as I know those are ignored when there's a screen sharing session active. Sure enough, turning off Energy Saving has stopped the display from going black for about an hour so far.

     

    This might just be a giant coincidence and the problem will return sooner or later. But certainly turning Energy Saving off has been the only way to keep the screen switched on without a screen sharing connection this morning.

     

    I just thought I'd share this to see if anyone else has tested this theory.

  • by MarkusWinter,

    MarkusWinter MarkusWinter Mar 26, 2014 2:37 AM in response to richardaustin
    Level 1 (4 points)
    Mar 26, 2014 2:37 AM in response to richardaustin

    > Has anyone tried disabling the Energy Saving settings especially for display?

     

    Pleased that it worked for you but it doesn't for me.

  • by Rixxi,

    Rixxi Rixxi Mar 31, 2014 6:58 AM in response to MarkusWinter
    Level 1 (0 points)
    Mar 31, 2014 6:58 AM in response to MarkusWinter

    Thought I had fixed this by switching keyboard, issu was gone for over a month... Bam, it's back. Keep ingnoring this Apple...

  • by MarkusWinter,

    MarkusWinter MarkusWinter Apr 25, 2014 7:32 AM in response to Stepppy
    Level 1 (4 points)
    Apr 25, 2014 7:32 AM in response to Stepppy

    Ok, now we are making progress, but I need some advice on wether I understand this correctly.

     

    I have an iMac 2009 where the display turned black after the hard disk has been exchanged (under Seagate exchange program). I could still see a VERY dim image of the screen when I shown a light onto the screen.

     

    According to the Service provider here it would need a motherboard replacement which was simply too expensive, and I didn't believe it anyway - it happened too soon after the hard disk replacement to be a coincidence.

     

    I bought a miniDisplay to DVI cable on eBay and hooked another monitor to my iMac.

     

    And voila: the second monitor does NOT go black when the main one does. If I understand it correctly then if it would have been the motherboard or the graphics card then both should be affected.

     

    Or am I getting this wrong?

     

    P.S. As the blacking out happened already during startup I used the "cmd F1" key combination to switch to the external monitor.

  • by pbook4g5,

    pbook4g5 pbook4g5 Apr 25, 2014 8:02 AM in response to MarkusWinter
    Level 1 (0 points)
    Apr 25, 2014 8:02 AM in response to MarkusWinter

    Hooking an external monitor up should have been one of the first things the service provider did (if they were following the troubleshooting steps provided via Apple's documentation).

     

    You are correct, though... if the external monitor works, then your logic board and graphics card are ok.

     

    In your case, it sound like the LED inverter board or the display/backlight itself.

     

    I'm still sticking by the cable that connects the backlight to the inverter board that's the culprit in all of these issues. Unfortunately, as I've pointed out earlier, this cable is the only one that you can't replace individually, and you have to get a new display/backlight (they are sold as one unit) with the cable attached.

     

    My replacement display has been running strong for over a year now, no issues. This is after replacing every cable I could, and the LED inverter board (twice, with brand new ones each time).

     

    Good luck.

  • by Floops,

    Floops Floops May 10, 2014 11:51 AM in response to pbook4g5
    Level 1 (0 points)
    May 10, 2014 11:51 AM in response to pbook4g5

    I've found the problem!!

    Mavericks for some reason overheats the GPU.

    I downloaded a free 3 day trial of Temperature Gauge Pro   http://www.tunabellysoftware.com/tgpro/

    It showed a GPU 0 diode temperature of 122 degrres C. I think that's about 250 degrees Farenhiet. Insanely hot. No wonder the poor thing was crapping out. TGP alows fan control and so I set them to maximum and watched the temp come down quickly.

    After all these months of frustration it turned out to be a simple fix. So I bought the program for $10. Sure a lot cheaper than having the Apple Experts replace a GPU or CPU like some have sugested.

    What I still can't figure out is why Apple won't fix the problem from thier end and just update the fan parameters on Mavericks.

  • by enderci,

    enderci enderci May 12, 2014 12:36 AM in response to Stepppy
    Level 1 (0 points)
    May 12, 2014 12:36 AM in response to Stepppy

     

     

     

     

    I'm thinking to the keyword "obsolescence". Same problem here, a fwe weeks after ending the 3 years protection plan :-(

     

  • by smegme,

    smegme smegme May 16, 2014 1:45 PM in response to Stepppy
    Level 1 (0 points)
    May 16, 2014 1:45 PM in response to Stepppy

    i have imac 27" mid 2011, I also have the problem of the screen going black, lasts a bit longer if i dim the brightness right down but still goes black, i have a feeling its power related as its seems like the screen dims the goes black, if I plug from thunderbolt to a tv the tv screen is fine just the imac screen going black, after taken to apple and they said it was the logicboard please pay apple £650.00 to fix it for you.

  • by Motorcycle Michael,

    Motorcycle Michael Motorcycle Michael May 16, 2014 3:33 PM in response to smegme
    Level 1 (123 points)
    Mac OS X
    May 16, 2014 3:33 PM in response to smegme

    If it displays and operates correctly on an external monitor, I doubt it's the logic board OR the video card, almost always the iMac's display. Having said that, you might check to see if this program applies to your 27" mid-11:

    http://support.apple.com/kb/TS5167

  • by smegme,

    smegme smegme May 17, 2014 1:03 AM in response to Motorcycle Michael
    Level 1 (0 points)
    May 17, 2014 1:03 AM in response to Motorcycle Michael

    Hi Motorcycle Michael

     

    they said while it was in apple they changed the video card as it was in the recall program but this was not the problem it was logicboard. just to update i did a hardware test full and it passed all tests including logicboard.

    since owning the imac they have done not all at the same time

     

    screen cleaning

    replace display unit

    replaced hard drive

    replaced video card

  • by callzhang,

    callzhang callzhang May 24, 2014 9:21 PM in response to smegme
    Level 1 (0 points)
    May 24, 2014 9:21 PM in response to smegme

    They did the same things to me: replaced video card, LED, backlid. The system still goes dark in less than a hour, but it lasts longer if the brightness turned to the lowest. Has anyone treid replacing the LED driver board? I think it could be the problem.

  • by MarkusWinter,

    MarkusWinter MarkusWinter Jun 11, 2014 11:50 AM in response to Stepppy
    Level 1 (4 points)
    Jun 11, 2014 11:50 AM in response to Stepppy

    Interesting. The screen on my 2009 27in iMac used to go black every few seconds. I have a "display sleep" hotspot in the lower right corner. So if it happens I go into the corner and back out again, wiggle the mouse, and the screen is back on.

     

    Now what wasn't the interesting part.

     

    Despite the hot corner it could go black every few seconds.However if after it comes back I set it to full brightness for a few seconds, then turn it back down, then it does not go black every few seconds. I can actually use the iMac for a few hours before it happens again. Hope that remains so.

  • by Tropical John,

    Tropical John Tropical John Jun 12, 2014 5:05 PM in response to Stepppy
    Level 1 (0 points)
    Jun 12, 2014 5:05 PM in response to Stepppy

    http://support.apple.com/kb/TS5167

     

    this might apply to you if your machine is a mid-2011 model with an AMD Radeon HD6970M video card.

     

    click on apple, upper left then about this mac then more info to find out what card your machine has.

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