2009 iMac G7 Display Won't Stay On

Discussion in 'iMac' started by snail17, Jan 4, 2012.

  1. snail17 macrumors newbie

    Apr 10, 2009
    OK... I have a late 2009 27" iMac G7 which has been great... until yesterday.
    For some reason now after restarting, the display will not stay on.
    The system boots ok (i get the startup chime) but immediately after this the screen display goes off (like it's in sleep).

    If I hit the F11/F12 volume control keys on the keyboard I get the increasing/decreasing beeps, so I know the OS is up & running.
    Also if I wait a few mins and hit a key on the keyboard the screen wakes up and I get the login box (my iMac is secured by password) and I can type in it, but only for a couple of seconds, then the screen goes off again.

    Have tried PRAM/NVRAM resets etc, but nothing works.

    It is still covered under AppleCare but I know they will just tell me to take it to my nearest Apple shop (40 miles away) and then wait the usual 10-28 days for them to fix it.
    Would like to know if there's anyone else has experienced this and if there's a simple solution.
    Everything seems to be working OK, but the display just won't stay on.

    Thanks all.
  2. snail17 thread starter macrumors newbie

    Apr 10, 2009
    2009 iMac Display Won't Stay On -An Update

    An update...
    Have tried plugging my HDMI TV in as a an external monitor and can see that the desktop is being extended OK. So I know for a fact that the OS is up & running.
    Sadly I still can't do much, as whenever I try to open anything it defaults to the main display (which isn't working). So am fumbling blind a bit trying to drag open windows from the main display to the external display (without much success).
    Does anyone know how I can change the display to show a mirror of the main display rather than an extension (bearing in mind that I can't see the dock to open system preferences etc.)
    Or does anyone have a clue what is going on here... my Apple doesn't seem to go wrong that often but when it does it does it in style.
    This is really frustrating as I know the system is working fine... and I even know the main display is working as it occasionally wakes up for a few seconds before going back to sleep again.

    Help anybody... please :(
  3. snail17 thread starter macrumors newbie

    Apr 10, 2009
    2009 iMac Display Won't Stay On -Another Update

    Another update....
    More by luck than anything else I managed to fire up System Preferences and drag it across to my working external display. Set display to duplicate rather than extend and I can use my iMac like there's nothing wrong on the external display... but the main display is still asleep.

    Surely I can't be the only person who has had this problem... could it be the logic board?? Seems odd that it's able to display the logon box even if only for a few seconds before going back to sleep....
  4. snail17 thread starter macrumors newbie

    Apr 10, 2009
    2009 iMac Display Won't Stay On

    So no-one able to offer any help or suggestions....???
  5. ljonesj macrumors 6502a


    Oct 20, 2009
    Kingsport TN
    your backlight or the screen its itself may be out setup an appointment to apple have them check it and get it fixed it might be odd but the video cable in the computer could have come off the connector not likely but it could have happened
  6. paulrbeers macrumors 68040

    Dec 17, 2009
    While I am no help with your issue (and agree you should take it in to an apple store if possible), what is a G7? Do you mean i7?
  7. snail17 thread starter macrumors newbie

    Apr 10, 2009
    2009 iMac Display Won't Stay On

    Yeah... sorry that's my mistake.
    Forgot Apple name their models after the CPU core not the 'generation'. So for G7 read i7 instead.
    It's a 2.8GHz Quad Core i7
  8. velocityg4 macrumors 601


    Dec 19, 2004
    The inverter board for the screen has likely failed. These are also known as a backlight board.

    The Apple Part Number for the Late 2009 27 iMac backlight board is 661-5311. You can find them used on eBay for $50 while they look to run $145 to $190 new when looking at Google Shopping through sellers with high feedback ratings. These are only listed as compatible with this model of iMac.

    I'd ignore the refurbished ones. They cost more than the regular used ones. You have no way of knowing whether refurbished just means dusted off and tested. If they actually replaced faulty electrical components on the board.



    Here's the replacement guide. http://www.ifixit.com/Guide/Installing-iMac-Intel-27-Inch-LED-Driver-Board/1639/1

    You need a T-10 torx and some good suction cups. You don't need anything fancy for the suction cups. I just use the ones that cost $0.50 at Ace hardware that have a hook for hanging pictures on a window.
  9. snail17 thread starter macrumors newbie

    Apr 10, 2009
    2009 iMac Display Won't Stay On

    Thanks for the info @velocityg4 and @ljonesj... that's really useful.
    What I find odd though is that the screen does wake... albeit for a few seconds only, but enough to see that the display is OK.
    I know you get dry solder joints etc. on PCBs but surely if its failed, it's failed... why would it occasionally work for short periods?

    I'm guessing that as the display goes off immediately after the grey screen and start chime during bootup, a reinstall of Mac OS X would be wasting my time, as the OS won't have loaded at this point... this must be hardware right??

    Oh well... thanks for all your help anyway... looks like i'll be having the joy of dealing with Apple customer services...
  10. eclipsegym macrumors newbie

    Jan 8, 2014
    I have the same prob

    Hi did you find what the problem was as I have the same issue?, pain in the backside. I took it to a company (not apple) who told me it was the backlight and it would cost £550 to get fixed!

    Hope you have the answer?



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