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 TooManyArtists,

    TooManyArtists TooManyArtists Jun 13, 2014 6:14 AM in response to Motorcycle Michael
    Level 1 (0 points)
    Jun 13, 2014 6:14 AM in response to Motorcycle Michael

    Motorcyle Michael, I saw your post on the connector and I have a couple follow up questions.

     

    Before you did this fix, how dim did you have to make your monitor before it would stay on?

    Has this fix proved to be a permanent solution? And finally, have you come to any conclusions about what specifically the issue was with the connector?

     

    And, to state for the record, I too am having the problem with my 27" imac where the screen goes black if I have it more than 4 or 5 dots on the brightness. I used to leave it at full brightness. Also, when I first got the computer (brand new from china), I noticed that it would have a slight buzzing sound if I dimmed it down. I'm not sure if it's related, but I wish I had brought it in and maybe I wouldn't be in this predicament now.

     

    I went in to talk to the the folks at the apple store and, as predicted, it didn't take long to find someone who knew my issue. They said that most likely I'd need a screen replacement (since they are one piece units) and it'd be $400-$500, which ***** because part of the reason I went with the 27" is because I figured the screen could still be used after the computer becomes obsolete!

     

    I'd like to try the Motorcyle Michael repair of fiddling with the connector and have it work, but I'd like to hear that it's worked and if anyone else has tried it.

  • by Motorcycle Michael,

    Motorcycle Michael Motorcycle Michael Jun 13, 2014 5:08 PM in response to TooManyArtists
    Level 1 (123 points)
    Mac OS X
    Jun 13, 2014 5:08 PM in response to TooManyArtists

    Hi TMA-

     

    Yes, it's still working. We never tried dimming display, used the sleep/wake trick until problem became unbearable.

     

    If you open up your iMac up, be very careful. Four delicate connectors just behind display, damage to any one of them = disaster. This is last resort, try everything else you can think of first. All I did was unplug/replug connector a few times, then secure it; it's so tiny, no wonder it lost connection. Expect it to keep working as long as it did from new, which is to say it shouldn't blackout again for a couple more years.

  • by JamesZhangToTheMax,

    JamesZhangToTheMax JamesZhangToTheMax Jun 14, 2014 11:57 PM in response to Motorcycle Michael
    Level 1 (0 points)
    Jun 14, 2014 11:57 PM in response to Motorcycle Michael

    Hi Mike. Thanks so much for your discovery, however I am a bit confused on the details. Can you please tell me how to:

     

    1. Remove the retainers

    2. Use the 'hook' to wring out the LED connector

     

    Also, is removing the retainers really necessary? Can I just use something like a toothpick or piece of metal to push the black LED connector in to the white socket to solve the 'loose' connection problem?

     

    Thanks so much!

  • by Motorcycle Michael,

    Motorcycle Michael Motorcycle Michael Jun 15, 2014 9:25 AM in response to JamesZhangToTheMax
    Level 1 (123 points)
    Mac OS X
    Jun 15, 2014 9:25 AM in response to JamesZhangToTheMax

    No, a toothpick won't do it as connector isn't necessarily loose. Next to retainer is the wrong end of a screw holding retainer in place; Removing that screw would mean dismantling entire display (not a good idea), so cutting tabs is a shortcut. Plug is down in a hole, hook tool allows leverage on plug sides to gently lift it out, a little at a time on each side. Access is too tight for anything else.

     

    Removing display is the hard part due to connectors on logic board, and potential for damage here is enormous. If you're at all nervous about it, suggest finding a shop that works on Macs to remove display, as damage to logic board will destroy the whole computer. Or take it to Apple and have display replaced. This is LAST RESORT, only after all other possible remedies for this specific problem have been tried, and it ONLY applies to LG's 27" LED-backlit display LM270WQ1 (SD) (A2). That number is on back of display, BTW.

     

    Don't risk making matters worse if you're at all hesitant.

  • by JamesZhangToTheMax,

    JamesZhangToTheMax JamesZhangToTheMax Jun 15, 2014 9:37 AM in response to Motorcycle Michael
    Level 1 (0 points)
    Jun 15, 2014 9:37 AM in response to Motorcycle Michael

    Thanks for the swift reply. I've already dismantled the LCD Panel successfully, removed the retainers, but I didn't need a hook to wring it out. I just pulled gently on the black cables and it easily disconnected. As a matter of fact, I posted my whole experience here.

     

    But if you don't have time to read it. Basically, after reconnecting and connecting, the screen (backlight) still randomly switches off. I even used wedges to secure it, but nothing helped. The funny thing is when I only connected one LED cable, the screen was half lit, but it didn't turn off at all. So I am stuck wondering why one LED connector cable can make the screen run consistently, while two causes it to randomly turn off. Do you have any ideas?

  • by Motorcycle Michael,

    Motorcycle Michael Motorcycle Michael Jun 15, 2014 10:43 AM in response to JamesZhangToTheMax
    Level 1 (123 points)
    Mac OS X
    Jun 15, 2014 10:43 AM in response to JamesZhangToTheMax

    LED driver board? Or the LED backlights themselves..... don't know how much side-to-side swapping you can get away with, or what would happen if you put connectors to opposite sides. You took the entire display apart?! Sheesh! I've done that a couple times to replace burnt-out CFL bulbs, decided it wasn't worth the trouble. Dude! (Just couldn't bring yourself to cut the tabs, huh. ;-) I'd be sorely tempted to solder those wires and eliminate the connectors altogether. Maybe I just got lucky, dunno, but you're _way_ into it now. Hats off to you, what you're doing is no easy job.

  • by grmac,

    grmac grmac Jun 23, 2014 4:34 AM in response to Motorcycle Michael
    Level 1 (8 points)
    Wireless
    Jun 23, 2014 4:34 AM in response to Motorcycle Michael

    I posted my first message in a different thread on this topic.

     

    I have a 2011 27" iMac which has the same intermittent black out problem.  I've taken it twice to the genius bar for complete tests over a couple of days.... you know, those diagnostics that we don't have access to.  They found nothing.

     

    I asked about the replacement video card program, but Apple won't replace the video card unless they can see it has a problem.  So... until I can show them the problem, they won't replace the video card.

     

    However.... I'm starting to have my doubts that it's a hardware issue.  I'm not totally sure, but I think this all started happening with the latest OS update.

     

    So what are we to do.... I can stabilize the iMac by running the brightness at the lowest setting (although occasionally I'll still get a blacked out screen) but that's hardly an acceptable solution.

     

    Are the latest iMac's exhibiting this problem?

     

    I'm not sure whether to replace it with another iMac or go with a rMBP.  I would go with a Mac Mini, but it is so far behind the curve now (no Thunderbolt 2, no USB 3, 3 year old processor).  The new Mac Pro is also another possibility I guess.

  • by Tropical John,

    Tropical John Tropical John Jun 23, 2014 7:06 AM in response to Stepppy
    Level 1 (0 points)
    Jun 23, 2014 7:06 AM in response to Stepppy

    If you think it is an OS problem (and my black screen issues started about the time I updated to Mavericks) maybe take it to the Apple store and get them to reinstall the OS the machine originally came with. Can't hurt.

  • by Tobias Brown,

    Tobias Brown Tobias Brown Jul 26, 2014 11:14 AM in response to Stepppy
    Level 1 (0 points)
    Jul 26, 2014 11:14 AM in response to Stepppy

    I had the identical problem with a mid-2010 27" iMac. It appears that I fixed the problem by wiping the hard drive clean and installing Windows 7 only on the machine. (I was only using the Windows side anyway via Bootcamp.)

     

    Here's my history with this problem: I took the machine to the Apple Store and after four days they said after continuous testing they could not reproduce the problem. No black screen for them. Miracles! When I initially brought the machine in the black screen occurred immediately after booting, so it was clear to them at that time that there was a serious problem. So, after four days, I went back and they said they'd replaced a couple of inexpensive fans that were not performing very well ($90) and that this was all they could do. They had initially told me out front that it was likely the graphics card and that would be $300 to fix. When I went in to pick it up with the fan replacements I mentioned to the repair person that the message boards often mentioned the need to replace the monitor. He said they had only one monitor in stock and that if I brought the machine right back in, they could switch it out within a day, not the 3-5 days. This would cost $600.

     

    Before I installed Windows 7 in this case that I'm explaining now, the screen would go black almost immediately in both Mac OS and Windows. The Windows install has been running steady for two days now with NO problem. It's too early to conclude this test but it appears that Apple's own OS system software, an upgrade or whatever (I think it actually started before I did the Maverick upgrade, which I did to see if it would resolve the problem) -- THEIR OWN SOFTWARE creates this hardware problem.

     

    If this proves to be true, this is an outrage! Can you imagine the number of non-technical people who will go through a hardware replacement for this ghastly problem, were the tech person likely requires an OS re-install, so it appears that the hardware switch fixes the problem but in reality it was merely a refreshed OS install that did it (and I admit that I'm speculating a bit here as I didn't try this with a Mac OS install). This has the appears of a very big problem with Apple. If this machine keeps working I'm going to attempt to make a formal complaint to Apple and post my case history in as many places as I can.

     

    I'm very hesitant to run the Apple Software Update on Windows for the Bootcamp drivers as maybe these "upgrades" contain the software issue that, again, appears to CAUSE this hardware issue.

     

    Please comment.

  • by Motorcycle Michael,

    Motorcycle Michael Motorcycle Michael Jul 26, 2014 12:42 PM in response to Tobias Brown
    Level 1 (123 points)
    Mac OS X
    Jul 26, 2014 12:42 PM in response to Tobias Brown

    I (for one) was dealing with a hardware problem here. Machine was running same MacOS before the problem was fixed as it has been running ever since (not related to, or qualified for, the video card program affecting other models). If the OS were the problem, it would certainly affect everyone, not just you. By the same token, if it's a hardware issue it will likely happen again, regardless of OS.

     

    If you can run the hardware test, not to worry, it does not "upgrade" anything, it only tests hardware and reports results. Don't know if AHT will run under Windows, but it didn't identify this particular hardware issue anyway.

  • by Tobias Brown,

    Tobias Brown Tobias Brown Jul 26, 2014 1:25 PM in response to Motorcycle Michael
    Level 1 (0 points)
    Jul 26, 2014 1:25 PM in response to Motorcycle Michael

    If it's a hardware issue (not Mac OS as I claim), how long would I need to wait to make a final conclusion here?

     

    I took this step because I read in some other thread of a businessman who had a few of these machines on which this started happening and he re-installed to factory and the problem went away. (I'll see if I can relocate that thread.)

     

    Maybe there's more than one cause. Some might be effected by OS, others by what you describe. At Apple Store, they ran tests for four days evidently and found no hardware issues. Indeed, they didn't replace any hardware because nothing except a fan was under-performing.

  • by Motorcycle Michael,

    Motorcycle Michael Motorcycle Michael Jul 26, 2014 2:08 PM in response to Tobias Brown
    Level 1 (123 points)
    Mac OS X
    Jul 26, 2014 2:08 PM in response to Tobias Brown

    I'm reminded of "2001, A Space Odyssey" and their Failure Mode Analysis: Run it until it fails, then do an autopsy. If it's usually a week between blackouts and machine has been fine for well over a month, you _might_ have solved it. Not very helpful, I know.

     

    That's the irritating nature of intermittent problems - absolutely the worst. If it's repeatable/predictable, it might suggest a solution. It took months to track this down because it only rarely happened at first. When it became more frequent and somewhat predictable, we substituted/replaced every video component between display and logic board - short of replacing display (with new cable/connectors attached). Was only desperation and the process of elimination that finally led to those connectors in my case. You might well be dealing with something completely different. Frustrating, to say the least.

  • by Tobias Brown,

    Tobias Brown Tobias Brown Jul 26, 2014 2:55 PM in response to Motorcycle Michael
    Level 1 (0 points)
    Jul 26, 2014 2:55 PM in response to Motorcycle Michael

    Did you try wiping the hard drive and installing back to the factory disks? Evidently not. (Sorry but it's a questions that has to be asked here.)

     

    Is anyone out there still dealing with this problem? Have you tried this possibility?

  • by Tobias Brown,

    Tobias Brown Tobias Brown Jul 28, 2014 2:01 PM in response to Tobias Brown
    Level 1 (0 points)
    Jul 28, 2014 2:01 PM in response to Tobias Brown

    Since my last post (and quite a few hours setting up Windows on my iMac27 with this issue), The Screen Went Black Again, so MM appears to be correct here. I won't waste any more time with this. Off to get the monitor replaced. (I'm not about to attempt the procedure he suggested, so the replacement I believe is the required action, no?)

  • by sglasser,

    sglasser sglasser Sep 6, 2014 2:17 PM in response to Motorcycle Michael
    Level 1 (0 points)
    Sep 6, 2014 2:17 PM in response to Motorcycle Michael

    So I too have the same issue with a 27 inch Mid 2010 iMac. I have the Radeon 5750 and would have loved (and expected) to see a recall extended for this issue due to the large number of common complaints. My unit started showing the problem 4 months out of warranty. After reading this entire thread have to admit the more logical explanation is a software / firmware glitch in the display itself and not the connectors, GPU or other components which have all been intermittent patches based on the posts. I know folks that get their problem solved often don't repost the success stories and hope if anyone here does find a real solution shouts it loudly for all to hear. I have a background in troubleshooting complex electronic mainframe sized systems with millions of components. I'm not familiar with Mac hardware anymore but my first job was repairing old mac classics and the late 80's early 90's vintage units :-) Apple has always had the approach of replacing components until the problem goes away so there probably aren't many technicians capable of actually debugging this problem.

     

    Here's my thinking. Like many other posts on this thread....no other issues observed when screen goes blank. Sleep and restart often works for a few minutes or seconds but rarely much longer.

    So I booted and held down the D key to start the Apple HW test. I feel this was informative though inconclusive. I ran the short test a handful of times - no issues found. (note, I did this after having issues with black screen every 1-2 seconds after leaving the sleep/hibernate state). I then ran the extended test twice in a row allowing the second pass to go overnight.

     

    Mind you the screen intensity is very bright during the apple HW test and didn't adjust with the keyboard controls. The screen never blanked on me for HOURS while running near full brightness and was still on the next morning. The unit was VERY VERY hot though. So I wouldn't recommend leaving the unit on overnight as I did...might lead to other issues. Another take away from this is the FAN was not even though the unit was tremendously hot. The self test includes a FAN test and I could hear the fan spin up and working. So very surprised it wasn't on and guess the folks that wrote the apple HW test disabled the fan intentionally.

     

    I'm using the unit today with no black screens though I'm convinced it will come back. I'm keeping brightness as low as I can stand it as it seems a logical way to reduce stress on the display...but I have no reason at this point to believe it makes a big difference.

    My main take away is this....

    The obvious hardware replacements aren't working.

    The problem has existed for some users for years and for others of us - only more recently. The software involved is probably a VERY flaky race condition in some firmware of the display circuit in the LED panel or LED driver that is going to be extremely difficult to debug even for apple engineers. What causes it to trip for each of us is probably very different depending on an infinite combination of hardware and software settings which is why changes that folks make seem to work for a period of time but are not "fixing" the underlying issue.

     

    I was about to reinstall the old OS as others had suggested but I'm thinking it also isn't worth a bother. I downloaded the SMC fan control and will give that a try as a workaround. I haven't used it yet.

     

    WHat I do think helps is to not HIBERNATE the unit. In all the debugging I did, the common action that seems to have had the best results is to actually SHUTDOWN each time I'm done with the unit and restart every time I sit down. I'll continue to do this, I'll try the fan software whenever I get black screens to see if it helps restore stability (but doubt it will help much). I also made sure my backups are intact in case the whole system outright dies. Don't forget the basics!

     

    I welcome any similar comments and encourage folks to keep voicing their complaints. Eventually someones bound to listen to either the fact there is a real issue that needs to be addressed or to sales numbers for iMACs that will drop as word of mouth about the reliability spreads. These are very expensive units. Very pretty....but hard to maintain. Unless we hear some success stories posted...I wouldn't pay to bring these units in for repair though that was my plan until this week. If i have to spend any money at this point, it will probably be to buy a desktop unit since those are going to be much cheaper and easier to repair out of warranty.

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