Previous 1 2 3 4 5 Next 202 Replies Latest reply: Jan 24, 2015 11:45 AM by Sunfiresaturn Go to original post Branched to a new discussion.
  • marcdl Level 1 Level 1 (0 points)

    Hi all,

     

    I have a 27" iMac from 2011 and also have the same issue. As others have mentioned, "ctrl + shift + eject" brings back the screen after several attempts.

     

    I've just been on the phone to Apple Support regarding this and they took me through steps to clear cache, reset the PRAM and clearing up some startup plist files. None of these helped though and I still had the issue. They have now suggested using the machine in safe mode (holding shift while booting up). I've been using it about an hour and haven't had any issues in safe mode. I will be reinstalling the operating system from scratch if safe mode continues to hold up so see if it helps. I'm also on Mountain Lion.

     

    As a side note, Apple recently did a product recall on iMac's from around 2009-2011 for a hard drive replacement. I thought this might fix the issue (as it seems to be sleep related). I've had the drive replaced and the problem remains.

     

    Anyone else had any luck fixing this issue?

     

    Marc

  • mebyard Level 1 Level 1 (0 points)

    Hello marcdl,

     

    I have had the "sudden video blackout" issue presenting itself since September 4, 2012.  It started not long after I upgraded to Mt. Lion.

     

    The symptoms are a sudden LCD backlight blackout, but the machine continues to run... AND the video is still there.  If you shine a very bright light on the screen at the proper angle you can see that the screen images are still bring projected by the video processor!  It is just that the LCD backlighting is off.

     

    And, no I've not had any progress in repair (since I am out of warranty and Apple has not declared this an engineering issue).  BUT I have written extensively in this thread about the workarounds that have helped me limp along.  Not all are convenient, but have been necessary since I use the machine semi-professionally and I've not has $$ to replace it as yet.

     

    1) I've found that the problem is exacerbated by heat.  NOW... I didn't say the problem is CAUSED by heat.  I believe the problem is an engineering problem.  But, at least in MY case, heat worsens the issue.  Consequently, I have implemented "heat reduction" measures.  I run a fan across the top of the case, left to right, to help pull air out of the vent.  This helps a lot.  ALSO, I run the brighness very low.  This means I have to darken the room.  No, I don't like working in a dungeon all day, but that's life at the moment.  If I run my brightness about 4-5 clicks above minimum and use the fan, I rarely have a blackout.  It also helps that we are in winter her in Oklahoma and I keep my office very, very cool.  In the summer, when my office heats up the issue will be more severe and so I plan to bite the bullet, and replace the machine and this time with APPLECARE!  I have also documented that the extra heat generated by heavily using the processor (Aperture or Final Cut Pro X or Photoshop) will exacerbate the problem.  If I am just word processing or reading, the problem is not as symptomatic.

     

    2) I've also learned (from others on this tread and other threads on other dissussion boards) that the keyboard shortcut for sleep [Command+Option+MediaEject] will sometimes actually invoke sleep and then after waiting a few seconds a repeat of this kestroke toggles the machine awake and usually the backlighting turns back on!  Normally it will be on  long enough for me to reduce the screen brightness and prevent another blackout for a bit.  If I can't get the machine to sleep with this keystroke I can hold the power button just long enough to "sleep" the machine, but not too long to power it off.  It's a fine art. ha

     

    3) On those days when the issue becomes persistant, I just have to get the machine to sleep, or force a shutdown, and let it cool.  After it has cooled, I can return to my work and use my heat managment stragegy to continue.

     

    Bottomline, and in summary, the problem is with the LCD Backlighting.  To my knowledge Apple hasn't acknowleged a problem as yet.  So in order for me (without warranty) to continue to use the machine I've had to implement heat reduction strategies.  No, they are not convenient, but it's called doing-what-you-have-to-do for the time being anyway.

     

    PLEASE continue to post your results with the SAFE MODE experiment.

     

    Thank you,

     

    Mark Byard

    Ponca City, OK

  • mebyard Level 1 Level 1 (0 points)

    Hello David,

     

    Did your OS reinstall finally rid your of the LCD blackout issue on your 27"?  How are you now faring?

     

    Mark Byard

    Ponca City, OK

  • marcdl Level 1 Level 1 (0 points)

    Hi Mark,

     

    I agree with all the points you mentioned. I also had the issue after upgrading to Mt. Lion. I've been running in safe mode for around 5 hours and haven't had any issues. Normally I would have encountered the issue several times in this period.

     

    Safe mode does disable a lot of features incl. graphics related processing so I assume it will generate less heat. I'm going to run safe mode until the end of the day and then reinstall the OS. I'll report back on my findings.

     

    I did tell the Apple Support guy about this thread and that others have had the same problem but he hadn't heard of the problem before. I'll send the link in future correspondence.

     

    I encourage anyone else who has this issue to post here - the more posts, the more likely Apple are to respond!

     

    Marc

  • mebyard Level 1 Level 1 (0 points)

    Thank you marcdl:  I will watch the thread and await your results.  Are you running the backlighting at normal intensities (i.e., about 3 or 4 clicks from max)?

     

    I am so far from an Apple Store that it isn't possible for me to be on their doorstep often enough to preciptate action on their part.  I can only call and that gets me no where; understandably, they need to SEE and TOUCH the hardware to be of any help.

     

    Thank you again,

     

    Mark Byard

    Ponca City, OK

  • marcdl Level 1 Level 1 (0 points)

    I've actually been running it at max, all the way to the top, since being in safe mode.

     

    Marc

  • mebyard Level 1 Level 1 (0 points)

    Amazing!

    Thanks for the data point.  We may be getting somewhere!

     

    Mark

  • DavidNY63 Level 1 Level 1 (0 points)

    Hi Mark,

     

    Happy new year.  I have not had any problems since reinstalling the operating system.

     

    All the best

     

    David

  • mebyard Level 1 Level 1 (0 points)

    Wonderful news David.  Did you go back with Lion or Mt. Lion?

     

    Mark

  • DavidNY63 Level 1 Level 1 (0 points)

    latest, 10.7.5

  • mebyard Level 1 Level 1 (0 points)

    Marc and on this thread:

     

    Two important data points to report:

     

    1) marcdl has determined (and I have duplicated his experiment and can coroborate) that if you boot into SAFE MODE (hold down the Shift key while booting up)  the LCD blackout issue doesn't seem to occur.  marcdl has been running his screen brightness at MAX for hourse with no blackouts.  I just repeated his experiment and found I too could run the brightness at or near max and not suffer a blackout.  This disables many of the core features of the OS like Core Audio and Core Video and etc. so many pieces of software dont' function well, if at all.  For example, if you are in SAFE MODE and try to invoke Launch Pad, you'll freeze the machine for several minutes while the video tries to create our launchpad screenshots.

     

    2) AND, poerhaps even more exciting, DavidNY63 just reported that after re-imaging his machine with Lion (10.7.5) he has had no more video blackouts.  I don't know what that means for those of us wanting to stay with Mt. Lion (10.8.x), but it is promising.

     

    I am in the middle of video production so I can't take the time right now to re-image.  But if there is anyone out there who CAN, and you are going back with Mt. Lion, PLEASE report your results here on this thread.

     

    Thanks all for reporting,

     

    Mark Byard

    Ponca City, OK

  • marcdl Level 1 Level 1 (0 points)

    Bad news unfortunately. I've had the LCD blackout a few times this afternoon despite being in safe mode. I was using Photoshop so again it seems to be related to process heavy apps that make the system run warmer. I will be on the phone to Apple tomorrow but will report back any progress I make.

     

    Marc

  • mebyard Level 1 Level 1 (0 points)

    Thanks for the update marcdl.  I'll look forward to hearing what Apple might say on this.  Regards,

     

    Mark Byard

    Ponca City, OK

  • sf1234 Level 1 Level 1 (0 points)

    I am having the same issue described above.  I purchased an iMac in July 2011, so unfortunately it is just past the warranty.  I suspect this is a bigger issue than Apple is willing to admit.  I also have another side display connected to the iMac via Thunderbolt, and that display has issues too (not the same issue, but a whizzing sound that gets very annoying after dealing with it for a few hours).

     

    The iMac tends to randomly black out, but everything else is functioning appropriately.  After reading this board, I lowered the brightness of my screen and downloaded smcfancontrol to increase the fanspeeds.  I usually have the problem around 5-6pm (after working on the computer for a whole day), but this morning it started early.  Since I lowered the brightness and started using SMCfancontrol, there have been no issues so keeping my fingers crossed...

  • mebyard Level 1 Level 1 (0 points)

    hi marcdl,

     

    Any ideas from Apple?

     

    Regards -- Mark Byard

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