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This Power Mac G4 has Mirrored Drive Doors.

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Why wont computer boot unless PMU reset is pressed

My sons Power Mac 1.0 GHz Dual PPC has gradually become harder to turn on. At first he would press the power button several times and it would eventually boot. Now, when the power button is pressed the LED inside lights up (goes out as soon as the button is released) but the computer won't start-up. I tested the PMU battery and it is 3.6 volts. I had almost settled on it being a bad power supply and had the whole thing pulled out, then I saw a PMU Reset button on the mother board. I put everything back together, pressed the reset button and the computer started working. However, every time the computer is shut down I have to press the reset and then press the power button to boot up. I really don't know what is wrong now. Obviously the power supply is working. The battery voltage is good. If the logic board was bad I wouldn't think the "Reset" button would make it run. Any ideas?

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Try replacing the 1/2 AA 3.6 volt PRAM battery

It’s located by the RAM slots, in this case it’s colored purple and black:

Power Mac G4 MDD RAM Replacement

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Have you tried unplugging the power cord and then plugging it back in? My MDD FW800 has developed what sounds like the same behavior and so far that is working each time. Most times I just cycle power on the power strip it is plugged into, but same thing remove power momentarily and re-apply. From the Apple forums this seems to be a common problem with these machines, but no solution yet.

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