Results 1 to 9 of 9
  1. #1
    iMac Black Screen

    Member Since
    Nov 05, 2011
    Posts
    6
    Angry iMac Black Screen
    I upgraded my iMac 20" today to Lion. Everything worked well. Then this evening the display went black. I rebooted and no difference. I can hear the computer work but the display remains black. I reset the PRAM: no difference.
    Help please.
    Mauri

  2. #2
    iMac Black Screen
    chscag's Avatar
    Member Since
    Jan 23, 2008
    Location
    Fort Worth, Texas
    Posts
    45,245
    Specs:
    27" iMac i5, 3.2 GHz, iPad 3, iPhone 5c, iPhone 6+, 3 iPods, Yosemite
    Do you have another monitor or TV you can hook up to your iMac to see if it works from the external display? Let us know.

  3. #3
    iMac Black Screen

    Member Since
    Nov 05, 2011
    Posts
    6
    Black screen
    I got it to work after resetting the PRAM. I believe it is an issue that Lion has with the Mozilla settings, as I learned from other forums.

    now the screen is back on but there is noticeable flicker when the CPU is working. I doubt this is a hardware problem as it happened right after installing Lion and after the black screen. Any thoughts?

    Thanks.

    Mauri

    Quote Originally Posted by chscag View Post
    Do you have another monitor or TV you can hook up to your iMac to see if it works from the external display? Let us know.

  4. #4
    iMac Black Screen
    chscag's Avatar
    Member Since
    Jan 23, 2008
    Location
    Fort Worth, Texas
    Posts
    45,245
    Specs:
    27" iMac i5, 3.2 GHz, iPad 3, iPhone 5c, iPhone 6+, 3 iPods, Yosemite
    I got it to work after resetting the PRAM. I believe it is an issue that Lion has with the Mozilla settings, as I learned from other forums.
    What Mozilla settings are you referring to? Are you using Firefox as your browser per chance? You can always switch back to Safari to see if the same flicker occurs. Flicker is usually caused by an improper refresh rate for your monitor. Go into your display settings in System Preferences and make sure they're set to reflect the native resolution of your iMac display.

  5. #5
    iMac Black Screen

    Member Since
    Nov 05, 2011
    Posts
    6
    black screen on iMac
    I claimed victory too early.... the iMac has gone black again. Same problem: I start it up, I can hear it's working, but the screen is black.
    Could it be a hardware problem? But the coincidence that this happened right after installing Lion makes me suspicious.
    Help please.
    Mauri



    Quote Originally Posted by chscag View Post
    What Mozilla settings are you referring to? Are you using Firefox as your browser per chance? You can always switch back to Safari to see if the same flicker occurs. Flicker is usually caused by an improper refresh rate for your monitor. Go into your display settings in System Preferences and make sure they're set to reflect the native resolution of your iMac display.

  6. #6
    iMac Black Screen
    chscag's Avatar
    Member Since
    Jan 23, 2008
    Location
    Fort Worth, Texas
    Posts
    45,245
    Specs:
    27" iMac i5, 3.2 GHz, iPad 3, iPhone 5c, iPhone 6+, 3 iPods, Yosemite
    Go back to my original reply to you and hook an external monitor or TV to the iMac. That's the only way we're going to find out if the problem is hardware related with your iMac or if it's something else. Let us know and we can go from there.

  7. #7
    iMac Black Screen

    Member Since
    Aug 15, 2012
    Posts
    1
    Connecting a second monitor worked for me. It allowed me to shut down the Mac using the shutdown command under the apple menu. When I restarted the iMac the monitor came back to life.
    This doesn't solve the problem of a perpetually sleeping screen but gets you out of it so you can keep working.
    BTW my monitor stayed black even after a forced restart (holding down the start button until it restarts). The Mac must be remembering the settings for a sleeping screen and start up with this in place.

  8. #8
    iMac Black Screen

    Member Since
    Oct 15, 2012
    Posts
    1
    Similar problem
    Hello,

    I have the same problem, but it isn't a Lion problem cause I've always been with snow leopard in my Imac 27". Yesterday everything worked fine in my computer, and this morning when i turned it on, the screen stays black. I know the computer is running because i can hear it, and if i press the play button in the keyboard i can get itunes to play. I tried connecting an external monitor and it works, but because its not the principal one i can't get the preferences window to open or any window to open.

    I also tried disconnecting the computers for a while, or booting it up holding cmd+opt+p+r, but nothing worked.

    Anyone has any idea of whats is the problem or the solution?


    Didz

  9. #9
    iMac Black Screen
    chscag's Avatar
    Member Since
    Jan 23, 2008
    Location
    Fort Worth, Texas
    Posts
    45,245
    Specs:
    27" iMac i5, 3.2 GHz, iPad 3, iPhone 5c, iPhone 6+, 3 iPods, Yosemite
    If an external monitor works OK, it has to be something related to the iMac display that's not working properly. First, make sure that the display is not sleeping all the time by resetting the System Management Controller.

    Do this: Remove the external monitor. Shut the iMac down completely, remove the AC cord from the outlet. Let the machine stay off for at least 10 minutes. Plug it back in and turn it on. Let us know.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. iMac 27 screen goes black
    By dmunroe in forum Apple Desktops
    Replies: 2
    Last Post: 05-18-2015, 04:34 PM
  2. Replies: 4
    Last Post: 04-23-2012, 06:59 PM
  3. iMac Black screen
    By vovin in forum Apple Desktops
    Replies: 3
    Last Post: 06-15-2009, 03:15 AM
  4. Imac Black Screen Problem
    By aj84se in forum Apple Desktops
    Replies: 4
    Last Post: 12-14-2008, 01:59 AM
  5. iMac G4 Black Screen???
    By iMacKid500 in forum Apple Desktops
    Replies: 1
    Last Post: 11-11-2007, 02:59 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •