Dead Power Mac G4 came back to life - explanations?

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Dead Power Mac G4 came back to life - explanations?

About two months ago I bought a used Power Mac G4 (a dual 450 Mhz Gigabit Ethernet). It was working like a charm with 10.4.11 for a few weeks, then I went on a trip for five days. When I came home, the machine was as dead as a brick. Nothing I did would bring it back to life, I tried PRAM resetting, etc. Then I bought a new internal battery and installed it. Still nothing. I tried leaving the machine for several hours after a PRAM reset, still nothing. Frustrated, I gave up. As it were, I left the machine plugged in to the power outlet but without any devices connected.

Earlier today, I decided to remove the hard drive from the machine and was just about to unplug it (I had forgotten that I didn't unplug it before) when I thought I'd try the pushing the power button. To my complete surprise the G4 booted up without any problems whatsoever. The clock had been reset of course but everything else works perfectly.

How could this have happened? I was convinced that the PSU was dead. Of course I'm happy now but if I hadn't left it plugged in and tried pushing the button today, I could have scrapped a working Mac...

Power Mac G4 Gigabit Ethernet, Mac OS X (10.4.11)

Posted on May 13, 2008 4:45 AM

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Answer 1

japamac

Level 7

24,400 points

May 13, 2008 5:02 AM in response to tonyingesson

Hi-

I think the G4's are what gave Apple the inspiration for OS X names, all cats....

Some G4's, especially the Sawtooth/Gigabit Ethernet models seem to have nine lives. Often, leaving a machine unplugged for a few days will return a G4 from the dead.
In your case, could be the PMU needed a vacation. Or, maybe the PSU has a weak connector where the cord attaches. Or the cord has a weak connector (replace cord with a known good/new cord is a recommended troubleshooting step).

Whatever the case may be, unless the machine repeats the problem, there's nothing to do but use the ol' girl!

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Answer 2

Limnos

Level 10

428,225 points

May 13, 2008 7:10 AM in response to tonyingesson

Although of course it could go back to giving problems again, so I wouldn't leave your homework or taxes until the last minute. 😉

I once had a IICx with a flaky PSU. If I plugged the monitor into the wall for a few minutes and turned it on, then unplugged the cord from the wall and plugged it into the monitor power socket on the computer the computer would boot. We figured the monitor was acting as a capacitor (and they contain some pretty powerful ones) and kick-starting the computer. Strange things can happen with Macs.

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Answer 3

May 29, 2008 3:18 PM in response to Limnos

Yeah even my old G3 B&W Plays Tricks on me like that sometimes well glad it up and working again

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Answer 4

May 31, 2008 9:22 AM in response to japamac

Touche^ I had gone on week's vacation and came back to a dead Mac. I had shut down but left the power strip on, NO worky? Hubby said we had a power failure but the power came back on after a couple hrs. Everything else worked on the power strip but my Mac. Dead, not even a split second light when I tried the main on button. finally (after ordering a power supply unit) it one day just decided to come on and been using it since. I wonder if a bad logic board since I have been having quirky problems for the past year. Now how do I determine if it's a logic board and where or how to find one?

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Answer 5

Jun 1, 2008 6:09 PM in response to Jan Olsen1

Don't do anything about the Power Supply or the logic board until you have replaced the 3.6 Volt 1/2 AA-size non-recharging battery on the motherboard. Non-operating after a power failure is the number one scenario indicating a bad battery.

Radio Shack carries them for about US$20, but online suppliers will send you one postpaid for under US$10.

After the battery is replaced, press deliberately and hold the tiny reset button nearby on the mother board for a quarter minute, then wait at least five seconds before attempting to start up. Avoid momentary presses, which can crash the microprocessor and use up your battery in a day.

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