This Power Mac G4 has Mirrored Drive Doors.

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Why won't it power up?

My G4 won't power up. I press the power button it turns on the off immediately. The fan tries to start but stops immediately. After I press the power button once, it won't light up again. I have to unplug the CPU and then plug it back in. Then when I try it again, same thing. I already replaced the little battery inside. Didn't help. This has been going on for a while. If I keep trying, sometimes it starts. I have the 867Mhz machine. What part is bad? Can I replace the faulty part myself? If so, is there step-by-step directions for this anywhere?

Answered! View the answer I have this problem too

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Its probably the power supply. A well know problem with the Powermacs. I'm listing an URL for a video on replacing the power supply in an MDD. The procedure is basically the same in most powermacs but ifixit has teardowns for other powermac models. Just check the teardowns page for your model if its not the MDD. Ralph

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Thank you. The video is helpful. Doesn't seem so bad to replace. Now if I could only find a power supply that doesn't cost more than the computer is worth. The MDDs are selling on e-bay for $175 or less.....


I don't know if you want to go there but heres a link to convert a regular PC power supply to work in a MDD. Ralph


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Have you tried resetting the "PMU" button on the logic board? This worked for me a while ago.

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Jim will be eternally grateful.
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