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 Txomin Sorrigueta,

    Txomin Sorrigueta Txomin Sorrigueta Apr 14, 2013 6:54 PM in response to yvettegri
    Level 1 (0 points)
    Apr 14, 2013 6:54 PM in response to yvettegri

    Thank you, man. This worked like a charm for me. I was about to open the iMac to try to clean the fan because I thought that was my heavy smoking habit the source of the problem. But fortunatelly I found your advice, muchas gracias from Spain.

  • by Gary Jaz,

    Gary Jaz Gary Jaz Apr 22, 2013 12:53 PM in response to SkinnyStudios
    Level 1 (0 points)
    Wireless
    Apr 22, 2013 12:53 PM in response to SkinnyStudios

    I have the same computer and am having the same trouble now.  Just started doing this the past week after running fine for almost 2 years.

  • by Winchy,

    Winchy Winchy Apr 23, 2013 10:01 AM in response to Stepppy
    Level 1 (0 points)
    Apr 23, 2013 10:01 AM in response to Stepppy

    I started having issues with mine about 3 months ago. The LCD would flicker a few times and it will dim about 20%. After a couple minutes, it'll go back to full brightness on its own.

     

    It kept doing that on and off, very inconsistently. Last night in the middle of an email, the LCD went black. I thought the machine had shut off, but pushing the power button brought it back to the point I was in so I know is not shuttinb off. Just the LCD went out.

    Now I can only have the LCD on for about 5 to 10 minutes before it shuts off again. Luckily, I have a side by side HDMI monitor, and that keeps working fine.

     

    I have an appointment at the bar today, but I am sooooo scared they are going to kill me there as I don't have the care package.

     

    This, just a week after my 2yr old mac mini killed the ethernet port and apple requested $400 to fix it.

    My mac mini is now a paper weight. Will my 2011 27" iMac become one as well?

     

    Stay tuned...

  • by pbook4g5,

    pbook4g5 pbook4g5 Apr 23, 2013 3:46 PM in response to Winchy
    Level 1 (0 points)
    Apr 23, 2013 3:46 PM in response to Winchy

    Don't worry... just don't let them fix it for you (or it will probably be super costly)

     

    If it was like my issue, it will be either the LED Driver Board (approximately $60 new on ebay and thats the first part I'd replace) or its your LCD display/backlight (I got a used one for $125 on ebay). From there, it could be your power supply or one of the cables or even the logic board, but I bet its either the board or the panel itself.

     

    All semi-easily fixable.

  • by Winchy,

    Winchy Winchy Apr 23, 2013 4:04 PM in response to Stepppy
    Level 1 (0 points)
    Apr 23, 2013 4:04 PM in response to Stepppy

    THanks for the info. I am now sitting at the bar and they are monkeying with it.

    We'll see what they have to say.

  • by Winchy,

    Winchy Winchy Apr 25, 2013 2:16 PM in response to Stepppy
    Level 1 (0 points)
    Apr 25, 2013 2:16 PM in response to Stepppy

    A quick update. Apple Geniuses ended up keeping the iMac overnight for observation. They said that just by me unplugging it, reset the power supply and the LCD driver and it may be enough. (hmmm... I am not sure about that, but OK).

     

    They ended up not being able to replicate the blacking out problem. Just brought it back home and sure enough, the screen is not going black anymore. All giddy and 10 minutes into the working session, it starts flashing and dimming again. This is exactly how everything started  2-3 months ago remember?

     

    I have money that says it will black out again soon. In which case, I know exactly what they are going to say. Let's put in about $600 in new parts. That should fix it!

  • by tootights,

    tootights tootights May 27, 2013 10:45 AM in response to Winchy
    Level 1 (0 points)
    May 27, 2013 10:45 AM in response to Winchy

    Is there any update on this???

     

    From what I can gather, the real issue here is the LCD backlight failing?

     

    jjhaffner what happened to your issue?

  • by XicoXperto,

    XicoXperto XicoXperto May 27, 2013 1:57 PM in response to tootights
    Level 1 (0 points)
    May 27, 2013 1:57 PM in response to tootights

    I took it to apple store and they tested it, on my case the logic board was failing

    This can be many different things...
    If you're not sure about what is the problem, take it to a apple store (or an authorized store), if possible that doesnt charge for the check of the mac, and they will tell you whats the problem.

  • by Gary Jaz,

    Gary Jaz Gary Jaz May 27, 2013 4:22 PM in response to XicoXperto
    Level 1 (0 points)
    Wireless
    May 27, 2013 4:22 PM in response to XicoXperto

    Hi all. My problem was easily solved. The old zap the pram actually worked.  Been fine for 2 months. 

  • by Winchy,

    Winchy Winchy May 27, 2013 4:27 PM in response to Stepppy
    Level 1 (0 points)
    May 27, 2013 4:27 PM in response to Stepppy

    Mine still dims and flashes about twice every hour. Three weeks or so of that game and the whole thing goes black. Power cycling brings it back for another 15-20 minutes and then it shuts off again.

     

    If I unplug it and let it sit for a while, the whole cycle starts over again. Three weeks of flashing and dimming until the screen shuts off.

     

    I really don't feel like spending $600 to repair this junk for now. I'll keep doing the power cycling until it dies for good. Then I'll get something else. You think you spend $2000+ on a machine and it'll be something descent... Nope!

  • by SkinnyStudios,

    SkinnyStudios SkinnyStudios May 27, 2013 4:46 PM in response to tootights
    Level 1 (0 points)
    May 27, 2013 4:46 PM in response to tootights

    I don't want to jinx a good thing, but my machine miraculously fixed itself.

     

    It has done this before for a few weeks before starting to act up again, however this time it has been good for a few months, so fingers crossed!.

     

    I did adjust the sleep and resolution settings a few times as there was a suggestion this issue may have something to do with the sleep function. Good luck :-)

  • by jjhaffner,

    jjhaffner jjhaffner May 28, 2013 9:37 PM in response to tootights
    Level 1 (15 points)
    May 28, 2013 9:37 PM in response to tootights

    Here's my final resolution, tootights.

     

    It was indeed the back light for the LCDs, but it was resolved in a roundabout way.

     

    I took it in, it wouldn't act up for them. So I took it home, followed all their trouble shooting tips and then it did for me again at home (surprise, surprise) and I took it back in. They ran tests and decided to replace the LED back light panels (there are two of them, on for the left half and one for the right half of the monitor). Repairs took several days, I picked it and it seemed fixed. About a week or so later I got a wonky flash and the brightness went up then down and when it settled down the left half was noticeably dimmer than the right half. So back in I go. They could see the left being visible dimmer, so this time they replaced the whole monitor assembly and all has been fine to date.

  • by pbook4g5,

    pbook4g5 pbook4g5 May 28, 2013 10:21 PM in response to jjhaffner
    Level 1 (0 points)
    May 28, 2013 10:21 PM in response to jjhaffner

    I actually don't think its the backlight, although it could be. JJ, your story leads me to believe that its the cable between the backlight and the backlight board... you know, the only one you can't replace yourself. When I replaced my LCD unit with a used one, my machine has worked fine ever since, but I saved my old panel.

     

    I took it apart and the cable end that attached to the panel (and not the LED driver board) seemed loose and looked discolored.

     

    I looked for just that replacement cable, but couldn't find it.... so, I think thats where these issues lie. Just my two cents anyway

  • by Winchy,

    Winchy Winchy May 29, 2013 6:59 AM in response to jjhaffner
    Level 1 (0 points)
    May 29, 2013 6:59 AM in response to jjhaffner

    jjhaffner, was this under warranty. That job had had to be over $500.

  • by jjhaffner,

    jjhaffner jjhaffner May 29, 2013 10:35 AM in response to Winchy
    Level 1 (15 points)
    May 29, 2013 10:35 AM in response to Winchy

    Wincy,

     

    Yes, I had the Applecare warranty.

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