14 Replies Latest reply: Apr 15, 2013 7:40 AM by Amigo500
Amigo500 Level 1 (0 points)

Hi everybody,


my 21,5" iMac, which i have bougth in Mid 2011, wont turn on its display.

I can boot it, and can hear the welcome chime, keyboard is also working.


But the display stays dark all the time.

I tried rebooting, and changing the power supply.


I am not at home right now, but i will try to reset the macs SMC. (turn off, disconnect from power, hold main power switch for 5 secons, and reboot)


Any other stuff i can do ?


Thank you

iMac (21.5-inch Mid 2011), Mac OS X (10.6.8)
  • BGreg Level 6 (17,495 points)

    See this Apple note on booting with no video.

  • Amigo500 Level 1 (0 points)

    Thank you BGreg,


    this kind of helped, because now it works, i did a SMC reset, Paramater Ram clear, and couple of reboots...

    now the display works, but i am not sure if it stays that way, because it went dark before just during normal operation, so i cant tell if its going to do the same again.

    if it happens again i guess i need to visit a service center.




  • Amigo500 Level 1 (0 points)

    hi again,


    another question popped into my mind, since the display is working now, can i perform something like a system check ? maybe something gets diagnosed and i can work from there...


    thanks again

  • BGreg Level 6 (17,495 points)

    You can run the Apple hardware test. Run the extended test, which can take over an hour.

  • Amigo500 Level 1 (0 points)

    thank again BGreg i will do that.


    Also, the display went dark again and i redid the SMC reset.

    I believe that i only just now did the SMC reset correctly, because i counted from 1 to 5 while holding the power button to get the exact amount of time, after that the display looked absolutly normal while booting lighting up right away in bright white, and its still working. i believe it really has to be exactly 5 seconds.


    i will do the hardware check to rule out any further issues.



  • Amigo500 Level 1 (0 points)

    hi again,


    i did both hardware tests, short and long, no problems have been detected.

    but it happened againg, the screen just stayed dark... then i played around and did the smc reset again, and rebooted alot, and suddenly it worked again and now i am using the imac to write this post...


    do you have any idea what i could try next ?

    maybe i could update to mountain lion ?


    Message was edited by: Amigo500

  • BGreg Level 6 (17,495 points)

    Good that the hardware tests came back with no issues. Before upgrading to Mountain Lion, apply the combo 10.6.8 release from the Apple site here. The combo release contains all the OS X 10.6 updates in one release, and can sometimes fix odd systems problems (this is easier than reinstalling the entire system). I'm not a proponent of upgrading operating systems to fix an issue (although that sometimes works). Much prefer to upgrade an operational system.


    Before applying the combo update, use Disk Utility to repair permissions, apply the update, then repair permissions again when done. Run Software Update in case anything else needs to be updated. While I don't recall this ever causing a problem, good practice is to have a system backup.

  • Amigo500 Level 1 (0 points)

    Thank you Greg,

    Right  now the screen is dark again after i tried to reboot...

  • Amigo500 Level 1 (0 points)

    and now its working again, i have really no idea what i am doing, it seems absolutely random, i will try the update now, thx again

  • mende1 Level 10 (92,171 points)

    If, after reinstalling 10.6.8, your iMac continues doing it, there's a hardware problem related to your graphic card or display. Note that Apple Hardware Test doesn't show problems related to the display or graphic card, based on old experiences

  • Amigo500 Level 1 (0 points)

    i reinstalled 10.6.8, can i somehow check that this went through correctly, like an update protocoll ? because all i can see is taht is 10.6.8, which it was before too..


    i also found some wrong permissions that needed to be repaired one of them looked like this:

    Abweichende Zugriffsrechte für „System/Library/CoreServices/RemoteManagement/AppleVNCServer.bundle/Contents/Su pport/LockScreen.app/Contents/Resources/English.lproj/MainMenu.nib“, Soll-Wert: drwxr-xr-x , Ist-Wert: -rwxr-xr-x .


    ive never heard of the lockscreen.app maybe this has something to do with my problems ?

    also, could it be a virus ? i know os virus programs are very rare, but are the a possible threat ?


    thanks again guys

  • mende1 Level 10 (92,171 points)

    If the installer showed that the update was installed properly, nothing to worry. You can reinstall Mac OS X 10.6.8 if you are already using this version.


    The permission has nothing to do with your problem, but repair it if you find wrong permissions. Apart from that, that's not caused by a virus, but if you want to make sure, install ClamXav or Sophos and run a test. However, it won't do anything to solve this problem

  • Amigo500 Level 1 (0 points)

    I did not see the installer message after rebooting, because the screen went dark again, i gave it some time to finish, like 30mins or so, and then rebooted, and everything seems to look normal update wise.


    Regarding the display problem, i dont know, it works now, could be randomly ok again though...

    It also went to energy saving mode,because i was afk for a while,  it was black (as it should) and when i pressed a button it immediatly went bright, so this seems to work too...


    I guess i have to try a few reboots to see if its really working now...

  • Amigo500 Level 1 (0 points)

    The problem still persists, but it is extremly random. Sometimes i can even go into screensaver mode and out of it and the display reacts fine. But sometimes the display just goes dark, and stays dark. When i try to reboot it works most of the time. ( I try to do a SMC reset everytime i reboot)


    I also have win7 installed using bootcamp drivers, just fyi...


    Anything else i can try ?