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 Boomer49,

    Boomer49 Boomer49 Nov 15, 2015 6:50 PM in response to MarkusWinter
    Level 1 (15 points)
    Nov 15, 2015 6:50 PM in response to MarkusWinter

    I took Psych 100 in 1967, and know that "correlation" does not mean "causality" ...

     

    But thanks for chiming-in ... everything helps.

  • by Boomer49,

    Boomer49 Boomer49 Nov 19, 2015 3:17 PM in response to Boomer49
    Level 1 (15 points)
    Nov 19, 2015 3:17 PM in response to Boomer49

    Four days and still working fine! As I posted on another thread ...

     

    Several days ago it started happening to me. I read everything I could find ... one thread was 17 pages long. The best I could do was run it at 20% brightness. If I got bold and tried to nudge it a bit higher ... <POOF> ...

    But, just as a wild guess and maybe in frustration I jammed (in one blazing nanosecond) that *!&*^#% screen brightness slider (in the Display section of the System Preferences App ... not the brightness button on the keyboard) to full 100% brightness. And nothing happened! It stayed on, and that was several days ago. The next day I tentatively lowered it to about 80% (where it had been set for a couple of years) ... and all is well so far. Try it. Nothing to lose.

  • by tabrings,

    tabrings tabrings Nov 21, 2015 9:13 AM in response to Stepppy
    Level 1 (0 points)
    Nov 21, 2015 9:13 AM in response to Stepppy

    My iMac (27-inch, Late 2012) is also having the same problem: after entering into sleep mode with the default settings of the Energy Saver the screen goes black and stops responding to the keyboard, mouse, and the power button.

     

    The only way to make it work again is to do a SMC reset by unplugging the power cord, wait for several minutes, plug the power cord, wait for more than 5 seconds, then pressing the power button.

     

    When did it start? About a week after updating El Capitan to 10.11.1.

     

    I have tried practically all the suggested procedures I could find in this support forum with no results. The only thing that seems to work is to shutdown the computer when I am not using it AND unplugging it from the wall. I also have observed that the longer the iMac is left unplugged, the longer it seems to go until the next time the screen goes black.

     

    Now I am trying the suggestion from Boomer49 above.

  • by Boomer49,

    Boomer49 Boomer49 Nov 21, 2015 9:42 AM in response to tabrings
    Level 1 (15 points)
    Nov 21, 2015 9:42 AM in response to tabrings

    Hey Tabrings,

     

    I've got my fingers crossed ... it would be great to know if I have been able to help someone.

     

    It wouldn't exactly be solving the mystery, but a fix is better than nothing.

     

    And if it doesn't work after a couple of tries, try minor tweaks and variations. Be sure to let us know how things work out.

     

    Boomer

  • by tabrings,

    tabrings tabrings Nov 21, 2015 9:50 AM in response to Boomer49
    Level 1 (0 points)
    Nov 21, 2015 9:50 AM in response to Boomer49

    Thanks, Boomer49. I set the brightness level at 100% following your procedure, and my Late-2012 iMac has been working well for 4 hours so far. I have set the Energy Saver to put the Display to sleep after 30 minutes of inactivity. Let's see if it comes back after going to sleep.

  • by Boomer49,

    Boomer49 Boomer49 Nov 21, 2015 10:03 AM in response to tabrings
    Level 1 (15 points)
    Nov 21, 2015 10:03 AM in response to tabrings

    Yahoo!!!!!

     

    Worth noting .... just to be on the safe side, I set the Go to Sleep schedule to NEVER. A minor but cautious idea. To heck with anything like defaulting to SLEEP. And, to sort of "allow" for that, I set the screen saver to the least energy-intensive possibility ... one single slowly-squirming coloured wormlike line writhing around on a black background.

     

    To **** with energy conservation ... I drive a 2001 Hyundai Accent ... very low carbon footprint.

     

    Soooo happy to hear about your results.

  • by tabrings,

    tabrings tabrings Nov 21, 2015 9:17 PM in response to Boomer49
    Level 1 (0 points)
    Nov 21, 2015 9:17 PM in response to Boomer49

    My iMac 27 (late 2012) just shutdown while I was in the middle of writing an email.


    Screen brightness was at 100% and Energy Saver was set to never go to sleep.


    Console Log says that:


    11/21/15 8:28:17.000 PM kernel[0]: Previous shutdown cause: 0


    Cause #0, according to other posts means loss of power.

  • by Boomer49,

    Boomer49 Boomer49 Nov 22, 2015 5:50 AM in response to tabrings
    Level 1 (15 points)
    Nov 22, 2015 5:50 AM in response to tabrings

    Tabrings,

     

    Well, that was disappointing news ... just when we thought that you were "on the road again" ....

     

    May I suggest that you once again do the old "slam it to 100% brightness as fast as possible" trick ... and then, if it's still OK after a few minutes, smoothly lower it back to about 80%. That would exactly duplicate my procedure, which seems to be still working for now.

     

    And 80% is just fine for most situations.

  • by Boomer49,

    Boomer49 Boomer49 Nov 23, 2015 2:43 PM in response to Boomer49
    Level 1 (15 points)
    Nov 23, 2015 2:43 PM in response to Boomer49

    Tabrings,

     

    Well, that was disappointing news ... just when we thought that you were "on the road again" ....

     

    May I suggest that you once again do the old "slam it to 100% brightness as fast as possible" trick ... and then, if it's still OK after a few minutes, smoothly lower it back to about 80%. That would exactly duplicate my procedure, which seems to be still working for now.

     

    And 80% is just fine for most situations.

  • by Boomer49,

    Boomer49 Boomer49 Nov 23, 2015 8:11 PM in response to tabrings
    Level 1 (15 points)
    Nov 23, 2015 8:11 PM in response to tabrings

    Tabrings,

     

    ???????????????????????????????????????

     

    You owe us a ******* reply.

     

    Maybe Buddy has shuffled-off this mortal coil. Has anybody else tried this "fix"?

     

    FFS, I am still here.

     

    And craving some feedback ...

     

    Ron

  • by tabrings,

    tabrings tabrings Nov 25, 2015 2:37 PM in response to Boomer49
    Level 1 (0 points)
    Nov 25, 2015 2:37 PM in response to Boomer49

    The display brightness is not related to the problem in my iMac. I tried various display brightness levels and my iMac would continue to randomly blackout. After a blackout, the only way to restart the iMac was with a SMC reset.

     

    After one of the blackouts I re-started the iMac holding down the D key in the keyboard to boot into Apple Diagnostics. The quick test did not find any problems, but when I selected the extended test, it seemed stuck at 34 minutes during the pass 1 of the memory check, even though it was running for more than 2 hours. I tried stopping the test but it did not respond to the mouse or keyboard. As it did not respond to the power on button, I pulled the plug.

     

    I pulled out the 8 GB memory upgrade I had installed about 2 years ago and left only the original 8 GB from Apple. I rebooted into Apple Diagnostics again and this time the extended test completed in less than one hour and found no errors.

     

    It seems that the problem was caused by bad memory. Now, with only the original memory that came with the iMac, it has been working without any problems for more than 2 days. The screen brightness is set to automatically adjust, and the computer sleep and display sleep have been working as expected.

  • by Boomer49,

    Boomer49 Boomer49 Nov 25, 2015 2:50 PM in response to tabrings
    Level 1 (15 points)
    Nov 25, 2015 2:50 PM in response to tabrings

    Aha! I'm happy to hear that you have that problem sorted-out ... two thumbs-up for stick-to-itiveness and never-say-die.

     

    It's weird that different folks keep stumbling-across such different Hail Mary fixes (a new keyboard, my "brightness slam", your recent memory tweak/re-set) for this one maddening symptom ... which even the Apple engineers/coders cannot cure/eliminate/diagnose.

     

    Thanks for the closure.

  • by MarkusWinter,

    MarkusWinter MarkusWinter Nov 25, 2015 3:46 PM in response to Boomer49
    Level 1 (4 points)
    Nov 25, 2015 3:46 PM in response to Boomer49

    Why would many different solutions be weird when a symptom can have many different causes?

     

    Displaying information on screen is the final element in a long chain, and is therefore affected by many different components.

  • by Boomer49,

    Boomer49 Boomer49 Nov 25, 2015 4:06 PM in response to MarkusWinter
    Level 1 (15 points)
    Nov 25, 2015 4:06 PM in response to MarkusWinter

    Yes, Grasshopper ...

     

    But this is 'way too FN Zen for me.

     

    F U ... y'all have a nice day.

  • by Boomer49,

    Boomer49 Boomer49 Dec 13, 2015 11:32 AM in response to Boomer49
    Level 1 (15 points)
    Dec 13, 2015 11:32 AM in response to Boomer49

    HI guys,

     

    Just an update, and my fix (explained on page 16) is still working. Better yet, I just received a congratulatory email from Apple Support this morning. On another thread here ... about  exactly the same problem ... I had suggested my idea to Gaetanfromparis. That was maybe two or three weeks ago. It worked for him too, and it's still working today.

     

    Here is the link ...

     

    Re: imac 27 black screen

     

    Hooray for me.

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