Model A1312 / Mid 2011 / 2.7 & 3.1 GHz Core i5 or 3.4 GHz Core i7 Processor

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Backlight on display is black on half of the screen

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My iMac Intel 27" EMC 2429 2.7GHz i5 has a large black area that looks like the back light has gone out. How do I know whether it's the backlight board or the LED?

Or even the video card? As suggested by Mayer in this post- Backlight dim in a part of the screen

I appreciate any help or feedback. Thank you,

Ben

Answered! View the answer I have this problem too

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Hey, Aaron! Thanks for the suggestion. I bought a thunderbolt cable and hooked up the iMac to another display. Using the Command + F2 keys there is NO black on the 2nd display, it looks perfect.

So, does that mean the video card is okay? It's either the LED backlight or the LED itself?

by

I feel confident after speaking and troubleshooting with the Simply Mac tech yesterday. It's not likely the video card, but rather the LED screen or the LED backlight.

'''HAS ANYONE EVER REPLACED THE 27" iMac LED Backlight Board?

Part # 661-5980'''

As shown here- http://www.powerbookmedic.com/27-iMac-LE... 54.html

It is MUCH CHEAPER to try and replace the LED Backlight Board than the LED screen itself. Obviously, that would be the first thing I attempt to replace, it seems like the most logical next troubleshooting step. If anyone has any other information or suggestions I would appreciate it.

Thank you

by

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I'm NEVER going to know if just repairing the LED backlight would have done the trick. My friend just gave me an LCD screen for free and now the iMac looks as good as new. Lol! Thanks, Michelle!

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It does sound like the symptom; of a video card issue. Please try to plug your tower into a another monitor just to make sure, that is the issue because the monitor may be on its way out the the great electronic beyound. If tried on another monitor and same problem is duplicated, the the video card may have to be replaced

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I feel confident after speaking and troubleshooting with the Simply Mac tech yesterday. It's not likely the video card, but rather the LED screen or the LED backlight.

'''HAS ANYONE EVER REPLACED THE 27" iMac LED Backlight Board?

Part # 661-5980'''

As shown here- http://www.powerbookmedic.com/27-iMac-LE... 54.html

It is MUCH CHEAPER to try and replace the LED Backlight Board than the LED screen itself. Obviously, that would be the first thing I attempt to replace, it seems like the most logical next troubleshooting step. If anyone has any other information or suggestions I would appreciate it.

Thank you

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I know this subject might be closed by now. I had the same problem with my 2010 iMac but this one has a 2T capacity and a very fast SAD drive on top of it. I really like to keep it running as long as possible.

Hooked up an HP monitor, colors and screen fantastic, iMac pushed under the desk and dimmed totally.

Backlight problem solved for me.

Hope this helps somebody.

Wolfgang

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benjibliss will be eternally grateful.
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