Results 1 to 5 of 5
  1. #1


    Member Since
    Sep 14, 2009
    Posts
    2
    Screen goes very dim
    My intel 17" mac has an almost black screen. It is too dark to see the mouse pointer but I can tell it is on. When I push the power button to force a shut down, the screen brightens for just a second and I can see a normal looking desktop before it shuts down. I have zapped the pram. I have hooked up an external monitor and it shows the desktop background but mirroring is not on so I can not use it to navigate. Any ideas?

  2. #2

    chscag's Avatar
    Member Since
    Jan 23, 2008
    Location
    Fort Worth, Texas
    Posts
    48,503
    Specs:
    Late 2013 27" iMac, iPad 3, iPhone 6s+, iPhone 6+, 3 iPods, El Capitan
    If the external monitor shows a normal raster (video) with correct brightness, we can assume the GPU in your iMac is working OK. It also means your logic board is probably OK. That leaves us with the internal display of your iMac.

    The symptom you describe may be a failing backlight (the CCFL which lights the screen) or it could be a defective inverter. Of the two, I would be more inclined to suspect the backlight. The inverter is a do it yourself replacement but does require care and skill. However, since replacing the backlight in the display, especially an iMac, is a daunting and difficult job, it's usually better to replace the entire display.

    And there may be other reasons your display is not functioning correctly....

    If your iMac is still under warranty, it would be best to have it looked at by Apple. If not, then you have a decision to make on how to go about repairing it.

    Regards.

  3. #3


    Member Since
    Sep 14, 2009
    Posts
    2
    Thank you for the info.

    I have taken the cover off and pushed in all the connections related to the inverter board.

    I started it up again and no problem with the screen. It is bright and clear.

    We will see if it stays that way.

  4. #4

    chscag's Avatar
    Member Since
    Jan 23, 2008
    Location
    Fort Worth, Texas
    Posts
    48,503
    Specs:
    Late 2013 27" iMac, iPad 3, iPhone 6s+, iPhone 6+, 3 iPods, El Capitan
    Sounds like you may have lucked out. Let's hope it was just a loose connection from the inverter. Keep us posted.

    Regards.

  5. #5


    Member Since
    Sep 14, 2009
    Posts
    4
    It might have also been the act of disconnecting the power that fixed your problem, rather than wiggling the internal connections. I believe the power management unit (now called the SMC) is reset by unplugging all connections for a few minutes.

    If it happens again, you could also try booting off the Mac OS X disk and see if it's software-related. (If it is, the screen should be bright when booting off the OS install disk.)

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. dim screen
    By NeoCool in forum Apple Notebooks
    Replies: 3
    Last Post: 02-08-2013, 03:42 AM
  2. Screen Dim
    By Nikonshooter in forum OS X - Operating System
    Replies: 4
    Last Post: 10-20-2009, 02:54 PM
  3. Screen Dim
    By lifeafter2am in forum iOS and Apps
    Replies: 4
    Last Post: 11-11-2008, 08:41 PM
  4. Dim Screen
    By avroncotton in forum Apple Desktops
    Replies: 2
    Last Post: 03-05-2008, 05:15 PM
  5. dim screen
    By christm in forum Apple Desktops
    Replies: 3
    Last Post: 03-10-2007, 11:50 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
  •