Apple Event: May 7th at 7 am PT
Intermittent black screen. Hard drive, music etc continue running but screen goes black. Restart only works for maybe a minute or two, sometimes only a few seconds. Is this hardware or software related? Definitely getting worse. Apple support talked me through a couple of resets but problem persists. Anyone have a definitive answer to this please?
iMac (27-inch Late 2009)
If you shine a flashlight at the screen can you still see the images on the screen or is it completely black? Trying to determine if it is the LED backlight or the whole display.
You may have to change the LCD display, i.e the screen. This needs to be done carefully to avoid damage and dust getting between the display and the glass. There are detailed instructions available online. It was only by replacing this major component that my iMac now works. They are not bad products but components do fail like any product. If its out of warranty then repairs can be expensive.
Thanks for the reply joparish. Would you agree I should try changing the cable of the backlight board first, before switching to the display?
joparish how much you new Display of 27 ' ?
They do fail so yes, before doing anything else it is worth trying this first. Good luck.
Are you doing it yourself? If you use an approved repairer then, with labor it should be around $300. Good luck.
Thanks !
Another symptom of my imac 27 is excessively heats the upper sector, mainly the left, even sometimes also heats up the acrylic to protect the LCD. Your iMac also had this overheating?
If no backlight board is causing the problem, as you say, the solution ought to be changing the entire LCD.
Thanks for your reply joparish
Hi, I hope you find this information useful:
A few years ago, we purchased iMac 27" 11,3 (Mid-2010) (with i7 2.93Ghz, ATI 5750 1GB VidRam, etc.) for our offices and software development team. They were originally shipped with Snow Leopard and worked as expected and without any problems. However, a year later, we upgraded to Lion and all of machines immediately exhibited the same problem: the screen would go to sleep by itself and would require a hard reboot or sleep on/off. (Only the screen was asleep and the rest of the iMac continued to function; this was confirmed by screen sharing to the machine.)
Due to the severity and impact on our business, we immediately contacted Apple and their genius bar staff in New York/SoHo. They were unable to determine the root cause, so they replaced all of the logic boards, video cards, and screens, and got us back online asap. This resolved the problem, but we were curious to know why. After days of rigorous testing, we concluded that the issue is caused by a bug in MacOS. Specifically, faulty Kext files (Kernel Extension files extend the functionality of the MacOS Kernel) for the ATI drivers. So, why did the replacing the hardware work? We think that the Kext files that were released and distributed with Lion (and later MacOS versions) correctly supported the newer hardware revision of the replacement components, but not the older ones.
If you're experiencing this problem, short of replacing the components or waiting (for another 3+ years) for Apple to hopefully fix their OS software, you can lessen the effects and be able to recover faster by doing the following: (Please bear in mind that these are not permanent fixes.)
If you're not convinced that it's a MacOS software problem, then do what we did and see for yourself; install Windows 7, Windows 8, or Linux via Bootcamp or as the only OS on the iMac. Those operating systems and drivers worked flawlessly for us; the bug does not occur and the screen does not go to sleep, but if you dual boot and switch back to MacOS, the bug reappears because the iMac is loading faulty Apple MacOS software.
Good luck!
27" iMac black screen
