fiona.mac

Q: iMac 27" Black Screen?

For 6 long and painful weeks, my 27" iMac (10.7.5) has intermittently turned itself to sleep mode (black screen). It's driving me up the wall and sent my productivity through the floor. You'll be in the middle of something and whammo, black screen. I have to push the power button to get the screen to work again. It doesn't respond to keyboard or mouse.

 

The screen turns black when you're on the Internet, playing quicktime files, using Microsoft office, so it happens across different applications... it happens on my account, my daughter's account, the guest account. It is indiscriminate, it just does it whenever it feels like it, but not all the time. If it shuts down video, the audio still plays, there is just a black screen with no picture to watch.

 

The computer is 8 months old and I have Apple Protection as well, so that's not the problem, but I see other people have experienced a similar issue and I'm up for suggestions as to what you think might be causing the problem.

 

So far, these are the fixes that have been done and NOT fixed the problem:

 

  • OSX has been reinstalled twice
  • The logic Board has been replaced
  • RAM has been replaced
  • The graphics card has been replaced

 

The tech is coming back out Monday to replace the power supply and the screen. If this doesn't work I'm told I'll be reissued with a new machine.

 

So any other suggestions out there? Is it possessed by a ghost? Cursed? Just should be declared a lemon?

iMac, Mac OS X (10.7.5), Bought July 2012, Built mid 2011

Posted on May 2, 2013 9:56 PM

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Q: iMac 27" Black Screen?

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  • by savbox,

    savbox savbox Oct 26, 2014 11:07 PM in response to Manuarmata
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    Oct 26, 2014 11:07 PM in response to Manuarmata

    If a semiconductor is likely to deteriorate or develop faults over time then perhaps you're right. In my 20 year experience with macs so far it would be a first and this particular iMac has indeed been working perfectly for 4 years. Only in the last month or so has it started blacking out, which is why I was wondering if some recent upgrade glitch has caused it. For me it's the obvious first step to try anyway. The HD was replaced about a year ago (even though the old one showed no signs of failing) and the machine also continued to work perfectly after that so I think the dislodged wiring theory doesn't fit either.

     

    My screen did black out again and so before putting it to sleep I used the monitor keys to turn the brightness setting down (obviously guessed how long to hold the key down as I couldn't see the screen dimming, it was already black.) Using my second monitor, I then woke the machine up, opened prefs>displays>gather windows then turned the iMac screen brightness slider back up to full. I put it to sleep again, woke it up and for a third time using this method the screen came back at full brightness and is still currently working. Guess I'll keep doing it until the method fails!

    Cheers

  • by nihaocaro,

    nihaocaro nihaocaro Oct 30, 2014 9:46 AM in response to savbox
    Level 1 (0 points)
    Oct 30, 2014 9:46 AM in response to savbox

    Hola,

    2 months ago I had the same problem. I was working one night on my iMac (27' inch 3.4 GHz Intel Core i7 4GB Mac OS X version 10.7.5) and boom, my screen went black, but the music in the background still playing, so I thought it was the heat because I've been editing photos all day, so I turned it off and turned it back on again later that night, and the screen was black, I couldn't do anything.

     

    I read this threat a lot, and did everything you guys said, but nothing. I even thought this replacement program was for me. So I took it to an authorized store and they said it was my logic board and it needed to be replaced and it would cost me $700. I didn't find that diagnostic logic because my computer was working, only not displaying anything, I could work with an external monitor or video beam, and everything was fine. So I took it to another authorized store in a different city (Mac Center, Medellín), and they said it was the backlight what need to be changed, so they ordered a new backlight board (part 923-0047) which costed me around $300 with installation.

    Its been a week and so far my computer is working fine, no black screen. If something else happen I'll post it. But for now, that was my solution.

  • by Manuarmata,

    Manuarmata Manuarmata Nov 1, 2014 11:10 PM in response to savbox
    Level 1 (0 points)
    Nov 1, 2014 11:10 PM in response to savbox

    mine is still doing well on 80% brightness since the last time i posted here, so that's about a week now.

  • by cyrano7,

    cyrano7 cyrano7 Nov 3, 2014 2:24 AM in response to Manuarmata
    Level 1 (1 points)
    Nov 3, 2014 2:24 AM in response to Manuarmata

    Well,

     

    I took my  late 2009 iMac 27 to the Apple place and they tried power board, no. Then they said "monitor for $500" and I said no.

    Then, I took it to a tech repair guy, he changed power board $250, and that did not fix it. He then said "monitor for $480". I said no.

    He gave me a 30 day-guarantee, so I got $200 back. He earned his money.

    I think the bottom line is, the Mac's are made in big, indivisible units. The cause may be a loose wire or $5 part within a much bigger part, but there is no way to get to it. They are not make to be repairable. There are no small parts, and the big parts are designed to be replaced, not repaired. End of story.

  • by savbox,

    savbox savbox Nov 4, 2014 12:32 AM in response to fiona.mac
    Level 1 (0 points)
    Nov 4, 2014 12:32 AM in response to fiona.mac

    I did have a gut feeling it was related to temperature but this morning it happened as soon as I switched the iMac on so possibly not. I still get the blackouts occasionally but the situation has stabilised and become more predictable since I started my routine; when a blackout occurs, turn the brightness down using the keyboard(guess how long to hold it down for) > send the machine to sleep then wake it back up; the screen always comes back at low brightness > don't turn the brightness up via keyboard but open the display prefs and up the slider to full. This always keeps the monitor on at full brightness for a few days. When it blacks out I do the same thing and again, stable for days.

    Interestingly a couple of days ago I thought since it was still happening, I may as well go back to using the bluetooth keyboard. The persistent blackouts came back almost immediately. I tried Manuarmarta's suggestion of 80% but in that situation it didn't help. When I reverted to the usb keyboard the relative predictability came back. Perhaps a coincidence and I can't think why the bluetooth keyboard would contribute, because I also have a bluetooth mouse and Wacom Intuos Pro (I have tried switching all bluetooth off but that didn't stop blackouts.)

    One thing is for sure, it seems pointless taking the iMac to get fixed because as this post also shows, people are consistently paying out huge amounts of money without joy. Only nihaocaro's solution seems to have worked so far. It would be interesting to hear if this same solution resolved anyone else's blackouts.

    Cheers

  • by cyrano7,

    cyrano7 cyrano7 Nov 4, 2014 10:53 AM in response to savbox
    Level 1 (1 points)
    Nov 4, 2014 10:53 AM in response to savbox

    Well, this is strange but good.

     

    Instead of adjusting the brightness with the keyboard, I went into the display systems preferences and un-clicked everything un-clickable and clicked them back. Then, still in the systems preferences, I adjusted the brightness to full blast.

     

    The darn thing works. For now.

  • by cyrano7,

    cyrano7 cyrano7 Nov 4, 2014 12:00 PM in response to cyrano7
    Level 1 (1 points)
    Nov 4, 2014 12:00 PM in response to cyrano7

    Specifically,

     

    In the ENERGY SAVER box, I un-clicked, and left UN-CLICKED

     

    put hard disks to sleep when possible

    wake up for network access

    start up automatically after a power failure

     

    Monitor still working

  • by savbox,

    savbox savbox Nov 4, 2014 11:05 PM in response to cyrano7
    Level 1 (0 points)
    Nov 4, 2014 11:05 PM in response to cyrano7

    I had the last two unchecked but have also now unchecked the first to see if it extends the time between blackouts.

    Cheers

  • by cyrano7,

    cyrano7 cyrano7 Nov 10, 2014 2:12 PM in response to fiona.mac
    Level 1 (1 points)
    Nov 10, 2014 2:12 PM in response to fiona.mac

    Well, a week ago, in the "Systems Preferences" under "Energy Saver" I unchecked the "Put hard disks to sleep with possible" and, the other two boxes under that, and my monitor is working perfectly.

     

    I suggest unchecking all boxes on the Screen Saver and see what happens. It worked superbly for me.

  • by cyrano7,

    cyrano7 cyrano7 Nov 16, 2014 4:40 PM in response to fiona.mac
    Level 1 (1 points)
    Nov 16, 2014 4:40 PM in response to fiona.mac

    Failure. After a week of working, monitor goes black.

  • by Manuarmata,

    Manuarmata Manuarmata Nov 16, 2014 9:16 PM in response to cyrano7
    Level 1 (0 points)
    Nov 16, 2014 9:16 PM in response to cyrano7

    Mine worked well for a week with the monitor at 80 % then it went black twice, now with the monitor an 100 % it works now for 10 days without issue. Fingers crossed but i think about changing the led inverter board myself eventually. it wil cost me 200 €. It contains capacitors and i begin to suspect them. @ cyrano, what parts are actually changed in yours?

  • by cyrano7,

    cyrano7 cyrano7 Nov 16, 2014 9:31 PM in response to Manuarmata
    Level 1 (1 points)
    Nov 16, 2014 9:31 PM in response to Manuarmata

    It was the blah blah board.  About 5 x 8 inches. 

     

    When that failed, they wanted to change the monitor panel (I hope I am using the right terms)

     

    Like many car repair places, I believe they use the slash-and-burn approach. They just change parts, which I understand, because there is no profit if they go digging around for a long time.

     

    I was quoted 2 prices, $250 for the board, and $480 for the panel. The odd thing is that changing one little setting on the energy saver made it work for a week.

    Some setting or connection must be very skittish. And I understand it is not cost effective for them to find the loose wire.


    I had this problem with 3 different OS, from 10.9.3 to Yosemite. I'm in Korea, which has hot summers and cold winters. It is cool now, and the problem still occurs, so it is not temperature related.

  • by NeilfromByron,

    NeilfromByron NeilfromByron Dec 4, 2014 12:29 AM in response to fiona.mac
    Level 1 (0 points)
    Dec 4, 2014 12:29 AM in response to fiona.mac

    Think I have found my problem, fixing it maybe a different story. It looks like the plug between the display and the motherboard has failed as there is nothing holding motherboard side of this plug down or to the motherboard. As I put the screen in each time I moved the screen it blacked out and by moving the RHS cable the screen came back on.

  • by cyrano7,

    cyrano7 cyrano7 Dec 4, 2014 2:04 PM in response to NeilfromByron
    Level 1 (1 points)
    Dec 4, 2014 2:04 PM in response to NeilfromByron

    That sounds logical. On another chat line, they said that the tech shop gave up looking for the problem, and just unhooked and re-hooked every connection. Problem solved.

    If I Iived closer to a repair shop, I would bring the Mac over and ask them how much they would charge to unhook and rebook.

     

    My screen works just fine, if it is below 30% brightness. Go over that and black.

    I'm going to gather some coins and buy a 27 inch LG monitor.

     

    Congrats.

  • by stbodie,

    stbodie stbodie Dec 19, 2014 8:13 AM in response to cyrano7
    Level 1 (0 points)
    Dec 19, 2014 8:13 AM in response to cyrano7

    I had these same sort of issues and tried everything. Turns out it is a known issue and Apple has a replacement program for the bad video card in many iMac models. The bad card causes grey screens, black screens, sleep issue, hard drive slowness, system spins, kernel panics, and more!  Wow, all fixed at no charge at my local Apple Store! 

     

    See:

    iMac (27-inch): AMD Radeon 6970M Video Card Replacement Program - Apple Support

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