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Yin Yang Level 1 Level 1 (0 points)

I have IMAC 27 inch mid 2011. The display keeps shutting off while in use. It shuts off automatically all the time. I have checked my screensaver setting and power setting. None of these setting is affecting the issue. I also checked the temp and it is compeletly normal (40*c). The screen is completely black no image at all. i don't think it is backlight issue.

I have brought to the apple store 3 times and they said that they run the system for 3 day and they were not able to reproduce the issue. I brought the imac back to home and it happens to me after 30 mins. Apple store said they cannot replace anythig if they can't reproduce the issue. Then i brought my machine to the third party service provider and they also was not able to detect the issue.


Please help.. i am still deseparately looking for the answer

iMac (27-inch Mid 2011), OS X Mountain Lion (10.8.4)
  • rkaufmann87 Level 9 Level 9 (50,695 points)

    How is it plugged into your home or office, do you use a power strip, UPS, directly to the wall etc... Also have tried creating another user account and testing in the new user account?

  • Carolyn Samit Level 10 Level 10 (100,205 points)

    Have you checked System Preferences > Energy Saver


    Is the Display set to to sleep after a certain amount of time?


    Have you tried Resetting the PRAM


    Or Resetting the System Management Controller (SMC)

  • Yin Yang Level 1 Level 1 (0 points)

    I have reset SMC and PRAM did not help. The machine is directly plugged in to the outlet. I thought about that and i bought a serge protector. But it still did not help. It is now happening while i am posting it.


    Is there any way i can make the power source more stable?

  • Yin Yang Level 1 Level 1 (0 points)

    Yes.. I also checked the power saver setting.

    This not only happens in Mac OS, it also happens when using windows bootcamp

  • Linc Davis Level 10 Level 10 (173,125 points)

    The next time you have the problem, note the exact time: hour, minute, second.


    If you have more than one user account, these instructions must be carried out as an administrator.


    Launch the Console application in any of the following ways:


    ☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)


    ☞ In the Finder, select Go Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.


    ☞ Open LaunchPad. Click Utilities, then Console in the icon grid.


    Make sure the title of the Console window is All Messages. If it isn't, select All Messages from the SYSTEM LOG QUERIES menu on the left. If you don't see that menu, select

    View Show Log List

    from the menu bar.

    Scroll back in the log to the time you noted above. Select any messages timestamped from then until the end of the episode, or until they start to repeat. Copy them to the Clipboard (command-C). Paste into a reply to this message (command-V).


    When posting a log extract, be selective. In most cases, a few dozen lines are more than enough.

    Please do not indiscriminately dump thousands of lines from the log into this discussion.


    Important: Some private information, such as your name, may appear in the log. Anonymize before posting.

  • drCurvin Level 1 Level 1 (0 points)

    This is happening to me as well.  I have yet to locate an entry in the systems log     which correlates with the screen cutoff.  However, if you have another Mac you can screen share the iMac that is turning off even when the console is black. This allowed me to close out importand stuff I was doing like dreamweaver with 10 unsaved php pages open before rebooting the system.


    On further experimentation I've found the monitor can be turned  back on by typing ctrl-shfit-eject (which is supposed to turn the screen off) and then pressing eject (or randomly spacebar).  


    My love of OSX and Steve are great.  Tim Cook's mangle of ML (including FTP service removal) is beginning to test my patience.  I run Ubuntu virtually as my web server as a result.  It won't be difficult to move everything to Linux if this persists. I'll lose products that are truly great like Dreamweaver, but if you can't do your work what's the point ?


    My monitor shut down 17 times while typing this message.  Would like to hear something intelligent Apple on this topic fairly soon.


    - Marc Curvin, M.D., MS BME

  • mpoling1 Level 1 Level 1 (0 points)

    I am having the same issue, mid-2011 imac 27".  I think this is a well documented defect as I have seen many posts online about it.  The consensus of online opinion is that it is an issue related to LCD and/or backlight.  In addition to the screen blacking out, I also have the dreaded "half grey screen" where half the screen appears to have a dark cloud hanging over it.  It is fitting. 


    I do not understand why Apple does not take responsibility and provide a FREE repair for this obvious product defect.  I have been using mac products since the late 1980's, a staunch supporter, willing to pay more for Apple products because they WORK...and they work more than a year or two.  This imac is the first Apple product I regret buying.  Apple.... where is your integrity on this issue? 


    Here are other links describing the problem - some dating back a year or more:


  • drCurvin Level 1 Level 1 (0 points)

    Resolution to the problem.  I called apple tech support and we conducted several tests to include refreshing performance ram and rebooting into safe mode for other tests.  Nothing resolved the problem so the technician (Jason) made an appointment for me the next day at our local Mac Store (Kenwood Center, OH).  At the Mac Store the technician pulled a cable out from behind the desk and plugged it into my iMac (mid 2012).  Every single component on the machine was tested and the results displayed on the monitor - it was really cool.  Everything checked and the technician said it was most likely the LCD / backpanel.  He replaced mine in about 15 minutes.  I took the machine home and have had no further problems.


    Mac tech support rocks !! 



  • Alkis64 Level 1 Level 1 (0 points)

    Same problem here, happend just a few days after warranty ran out and Apple refuses to aknowledge that it is a rather common problem. So I was offerered by my dealer's workshop to replace the display for $ 900,-. I refused, as I thought that I could deal with a display that would go black every now and then for another year or so.Even worse: After getting the iMac returned from the workshop today and I turned it on only to find out it is now completely dark. Now what? Spending those $ 900 or investing in a new one? Risking a loss of more money after this expirience? Or having to spend a lot more only to buy an additional warranty?


    Being a loyal customer for the last 25 years I felt let down by this lack of customer support.

    Unfortunately we don't have an Apple Store and Apple Support on the phone made it clear in harsh words that there will be no changes in their policy.

  • drCurvin Level 1 Level 1 (0 points)

    What organization is "my dealer's workshop" ? There was another ref to some "Apple Authorized Repair Shop", etc. If you take a Mac to a Mac Store (as I did) they will run diagnostics and then repair it. The cost out of warranty would have been about 450$ to replace my 27" LCD.  Not bad for a $3500 computer that I will use at least another 5 (more like 10) years.  Avoid the ma and pa computer stores - they can't fix your Mac (unless they send it to back to Apple) for you.

  • Yin Yang Level 1 Level 1 (0 points)

    Hey guys...


    Good news for this issue, I went back to apple authorized repair after 3 weeks from 1st visit. This time the tech was able to detect the issue and replaced LED backlight display board. Since my mac is still under warranty, it was covered. But the cost of LED backlight displaybard is 138$ and i don't know the labor cost.


    Seems like the issue has been resolved. I have not encountered any black out issue since. I hope this fixed permanently. Another thing i realized is that IMac 27 mid 2011 usually produce a lot of heat especially when you overstress the machine such as using a lot of graphic. I think this might shorten the life span of the machine.

    So i have decided to increase the fan speeds when i play games or use the machine for a long time. I use smcfancontrol to adjust the fan speed when needed.


    Thank you for contributing to this discussion.

  • rwcoch Level 1 Level 1 (0 points)

    Any screen issues since replacing the LED board? I am debating where to attempt a replacement for my 2011 iMac. At this point, any information helps. Thanks in advance.

  • Yin Yang Level 1 Level 1 (0 points)

    Nope... i haven't encountered the issue again. My screen is working perfectly.

  • OPina Level 1 Level 1 (0 points)

    Thanks Yin Yang for documenting this issue as you did. Mine has the quite common dark half screen issue. After testing all posible solutions, chequed all display connectors etc, etc, I decided to replace the led Backlight board. I will post the results when installed.   

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