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AnotherMortal

macrumors regular
Original poster
Jan 14, 2003
148
1
Baltimore
So I had a Digital Audio G4 come my way in need of service, and the symptoms were odd. Fans were running, but machine wouldn't power up. Power LED only stayed on as long as I held in the power button.

User said machine had locked up and they pulled the power cable (eek!) on it, then it started doing this.

So I tried the following:
upluggged all peripherals - - no change
removed all cards save video -- no change
reset the PMU -- no change
replaced onboard battery -- no change
replaced power supply -- no change

So before I went on replacing more expensive parts, I asked a coworker about it, and he had me plug everything back in, opened the side door, powered on the machine once, then reached in, held down the PMU reset button while the power was on, held it for 10 seconds, then hit the power button again. Tada, start up chime.

Now, my question is, wtf? I looked for about an hour, and I couldn't find any apple document saying to leave the power ON when resetting the PMU. They explicitly stated removing the power cable first.

Has anyone else fixed an a problematic Powermac by this slightly unorthodox PMU reset procedure?
 
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