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Question: iMac 20" White Screen, then Black

I have received an iMac A1224, 20" 2.4Ghz/1Gb/320Gb/SD/AP/BT that won't start up.

I hear the power-on chime, the screen flashes white for a second, then goes black and stays black.

After a minute or so, it flashes on again for a second, showing the Apple logo and a progress bar 2/3 done.

Then the screen goes black and stays black.

I have tried resetting the PRAM a number of times, but it doesn't change anything.

I tried pressing the power button while plugging it in and all that happened was the fans went to high-speed and stayed that way until I turned it off and unplugged it.

There's nothing plugged into the iMac except keyboard and mouse.

It seems like the display is OK, but something is interrupting proper startup.

What could it be?

iMac, Model A1224, 20", 2.4 GHz, 1Gb, 32G

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Nov 18, 2017 2:19 PM in response to tfeledy In response to tfeledy

Hello tfeledy,

Thanks for asking the Apple Support Communities for help with your Mac. I have a few articles to help.

First, I recommend trying this help article: If your Mac won't turn on - Apple Support

It has lots of great steps, helps to rule out the display, and also has you try the SMC reset, which I recommend to correct the fans running at high speeds.

The next article I recommend is testing if you can get the Mac to boot in safe mode: Use safe mode to isolate issues with your Mac - Apple Support

If you can boot up in safe mode, that article has a section titled "If an issue doesn't happen in safe mode" for the next troubleshooting steps. If you need more help, please include the current operating system running on the Mac if you know it, and if not, if you have any DVD's that came with the iMac. Thanks and have a great weekend.

Nov 18, 2017 2:19 PM

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Question: iMac 20" White Screen, then Black