Model A1312 / Mid 2011 / 2.7 & 3.1 GHz Core i5 or 3.4 GHz Core i7 Processor, ID iMac12,2

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Black screen. External monitor working

The Mac starts up and runs probably on thunderbolt to vga adapter but the built in screen remains black. It has an AMD HD 6770m graphics card so not the one under the repair program.

Any ideas what could be the problem?

Answer this question I have this problem too

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To be clear here: You are able to run your system via an external monitor - correct?


Can you give us the last four digits of your serial number so we can identify which model you have.


Yes the external monitor works.



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See if you shine a flashlight into the display at a sharp angle if you can see the faint image of your desktop & an external display works, then you know the LCD's backlight services needs repair.

But, ... Without knowing which model you have I can't tell you more.

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Yes there is faint image. I thought there wasnt but i managed to log in and see the dock.

The model is A1312

EMC 2429

Im leaning towards the backlight inverter but not sure how to test this?


I've had a few LED driver board go on me. Here's the IFIXIT guide to get to it and replace it: iMac Intel 27" EMC 2429 LED Driver Board Replacement


I've ordered the board. So I will see how that goes when I get it. I'm sure I will be back on here if all goes wrong.

Thanks for your help.


Take your time and don't force things as some of the connectors are fragile!


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lcrooks will be eternally grateful.
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