Repair guides and support for 24" Intel iMacs by Apple.

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LCD Power / Boot up issues

I have a 2007 iMac I've been working on. Originally the computer worked fine then I started having issues with it not booting up.

It seemed if I held the power button longer than usual that would allow it to boot up sometimes.

It was a problem with the video or LCD cause soon as it hit LED 3 the machine would quit and have to be unplugged to continue.

I replaced the video card and still have the same problem. The only way to get the computer to boot up is to unplug the inverter cable from the back of the LCD (9 wire black cable). The computer boots up and runs like normal. You can see that the LCD works if you shine a flashlight on it.

From what I've read seems like its probably a problem with the backlight board on the LCD and not the power supply? Is it worth replacing? Thank you for your help!

Brandon S.

Answered! View the answer I have this problem too

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I'm going to go with a bad power supply. I also have a 24" 2007 iMac that did exactly as you describe. I pulled the power supply, replaced a few lightly-swollen capacitors, reinstalled, and it worked fine afterwards.


did u buy the capacitors online? unfortunately i do not have any reliable local connections, i hate the idea of having to "junk" this machine...


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@scoom1982 sounds like a bad inverter. Check your inverter cable and the power board. Let us know the exact model of your computer. Enter the model number on this site and let us know what it shows for your computer.

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Model A1225, 24" screen, 2.8GHz, 2GB RAM, just bought and installed the new inverter cable but made no difference, not sure on checking the power supply, i have the multimeter and tools to check it but have read there are some different PSUs that were put in this machine, do they all have the same diagnostic procedure? I have also read that if the computer boots ok without the LCD inverter cable plugged in its probably something else (backlight board on the screen)? I went to a local shop but they did not help at all

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Brandon Shannon will be eternally grateful.
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