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

52647 Views 154 Replies Latest reply: Mar 31, 2014 6:58 AM by Rixxi RSS
  • Txomin Sorrigueta Calculating status...

    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.

  • Gary Jaz Calculating status...

    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.

  • Winchy Level 1 Level 1 (0 points)

    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...

  • pbook4g5 Level 1 Level 1 (0 points)

    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.

  • Winchy Level 1 Level 1 (0 points)

    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.

  • Winchy Level 1 Level 1 (0 points)

    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!

  • tootights Calculating status...

    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?

  • XicoXperto Calculating status...

    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.

  • Gary Jaz Level 1 Level 1 (0 points)

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

  • Winchy Level 1 Level 1 (0 points)

    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!

  • SkinnyStudios Calculating status...

    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 :-)

  • jjhaffner Calculating status...

    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.

  • pbook4g5 Level 1 Level 1 (0 points)

    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

  • Winchy Level 1 Level 1 (0 points)

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

  • jjhaffner Level 1 Level 1 (15 points)

    Wincy,

     

    Yes, I had the Applecare warranty.

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