[Kirkman]

I have a PowerMac G4 MDD, dual 1ghz.

My wife has noticed that occasionally the machine shuts down by itself when it is asleep. I didn't think anything of this, because it's only happened a few times.

But now, there is a new wrinkle. After one of these self-shut-downs, when I try to turn the G4 back on, it won't start. The power light on the front lights up while I hold the button. If I let go, it fades. The hard drive never spins, teh fans never start. There is no sound.

I unplugged the power cable overnight and re-plugged it in this morning. The machine then booted fine.

Anyone have any idea what's going on?

[gangster]

sounds like it is really just asleep, not off until unplugged. did you check the power saving settings already?

[Kirkman]

No, it was shut down. The computer's light was off and it would not "awake" when pushing mouse buttons and keys. Power saving settings are normal, nothing that would make the computer shut down by itself.

[©öñFü$íóÑ]

You could check the following in the mean time...

1) Is your power supply clean? Is it choked-full of dust?

You can try taking it out of the G4's case and try cleaning it with a few swabs and a long, really, REALLY narrow, vaccuum hose... preferably while you are standing on a wooden, vinyl, or ceramic floor and not wearing shoes or socks so as to minimize any chance of static.

If the power supply can't dissipate heat, it'll logically force everything to shut down. I mean, at least that's what happened in my PM 6100 when it was full of dust...

If for some reason it still keeps shutting down on it's own even after cleaning it, maybe you can replace the power supply itself. I'm not sure if you can replace it with just any standard ATX power supplies that you can buy in your local computer store, but you're more likely have to take it to an Apple-authorized repair shop or service center in the case that the G4's PSU only accepts a PSU of specific physical dimensions/measurements or has special connector pins or something. WeLoveMacs.com has a pretty good selection of PSU's, but they're in the $100-300 range...

2) Maybe your G4's internal lithium battery needs changing...

I'm not exactly sure if G4-G5 owners would ever experience the symptoms we old "pre-G3" users did when our lithium motherboard batteries started dying; the system clock keeps forgetting its settings, the date keeps resetting back to 1906/1956, there's no video on the monitor until the battery is changed....

[Lucibelle]

This exact same thing is happening to me, except if it DOES manage to boot, it will shut down minutes later, even when booted from the OS X.4 install DVD. I tried everything...took out all non-factory cards, switched RAM, did logic board reset, changed battery....everything I or anyone else could think of.

I had been getting plagued with kernal panics, so I ran RAM test with both memtest and Apple hardware diagnostic cd, (overnight on both) RAM was fine, encountered a few minor HD problems with Tech Tool Pro, but those were fixed. Ran DiskWarrior, no change in problems, then was about to wipe clean and reinstall the system onto original ATA drive (which tested fine) when the Mac was constantly putting itself to sleep, (set for never sleep) but it shut down shortly after starting the erase process while being booted from the DVD.

So now, after all attempts to fix it, it won't start up. I have the same model G4 1GDP MDD machine as Kirkman and I have the same result...light comes on when I press the startup button, goes off when I release...no fans, no chime, no nothing. It DOES manage to start up once in a while during an attempt, but there's no chime. Still, it starts up fine and runs the install DVD, (existing hd now blank) but then shuts down in a matter of minutes, whether I'm trying to run anything off the DVD, or it just sits there. I've checked the cords, vents, and everything you could think of, but there are no problems that I can find. This is no longer a 'simple fix'.

What's worse is that I don't know if taking it in for service is even worth it, considering I'm seeing this model on eBay for just over $1000. I'm done trying to figure it out myself, and service + parts could add up quickly. We have a Mac Mini, which I'm currently using, but we used the G4 DP tower for our music production, which needs more muscle than the Mini can handle.

If anyone has any further ideas, I'll look into it, but I believe that the logic board is done.

[wubrew]

bump

[Big Mac]

Did you reset the PMU?

[falcovandermaden]

Since yesterday (26 march 2007) (during an Apple update) the Powermac G4 suddenly shuts down. Immediate restarting isn't possible. After waiting some time I'am able to do a startup, but after some minutes it shuts down again. This process keeps appearing over and over.

What I did:
- tried to reboot from OSX CD -> Still shuts down
- changed the battery -> no fix
- Reseted the MPU -> no fix

Could it be that a fan is broken, so the processor runs hot and the computer does a safety shutdown?

Anyone found a solution yet?