[kenfused]

My G4 1ghz dual won't power up after a power outage this AM. It IS plugged into a nice APC UPS unit, power was off for about 2 hours.
When I try to turn on the computer now, when I put my finger on the monitor (apple 30") power area or on the main CPU, the white LED lights, but then no activity, no boot up, no fans, no HD sounds...

Tried unplugging and putting into the wall directly. Still no go.
I don't think anything should be fried since it was in a UPS, but who knows...

Any ideas?

[reader50]

Press & hold the CUDA reset button on the motherboard for a few seconds. Then try to boot up again.

[cms]

If that doesn't work, take out the little purple battery and leave it out for at least 20 minutes. Then, pop it back in and fire up the G4. You'll be back in business. I know, as I've done it on dozens of supposedly "dead" machines. Something odd happens to the PMU on these machines, so it's good to know what to do when this situation develops. You may find that replacing the purple battery sorts out the issue.

[kenfused]

THANKS!
The button fixed it!

[nlr154]

Originally Posted by cms 

If that doesn't work, take out the little purple battery and leave it out for at least 20 minutes. Then, pop it back in and fire up the G4. You'll be back in business. I know, as I've done it on dozens of supposedly "dead" machines. Something odd happens to the PMU on these machines, so it's good to know what to do when this situation develops. You may find that replacing the purple battery sorts out the issue.

I've had the same problem the OP has...although it's a G4 DA 733. I tired that button, bought a new battery...nothing. I figure the power supply or the video card is messed up. Anyone have any other suggestions to figure out how to make it work?

[reader50]

Originally Posted by nlr154 

I've had the same problem the OP has...although it's a G4 DA 733. I tried that button, bought a new battery...nothing. I figure the power supply or the video card is messed up. Anyone have any other suggestions to figure out how to make it work?

Assuming your power light goes on like the OP's does, then you are getting something from the power supply. Try pulling the graphics card and booting blind. If the card is defective, you will at least hear the startup sound and HD activity.

[nlr154]

Originally Posted by reader50 

Assuming your power light goes on like the OP's does, then you are getting something from the power supply. Try pulling the graphics card and booting blind. If the card is defective, you will at least hear the startup sound and HD activity.

Hmm I haven't tired that....
I get the light to show only when I push the power button. Once I let go - the light goes out. I don't hear anything kicking on...fans or HD....

I will try that next! Thanks!

[reader50]

Also, try pulling all your USB peripherals. So nothing is plugged into the PowerMac via USB. USB devices can hang up boot if they go bad.

[Jonesy]

I have exactly the same problem. It happened every time the power supply was lost. Until recently resetting the PMU fixed the problem. Now it doesn't help. I have bought a new battery as the old one was dead but this has not helped.

What happens if you press the PMU button more than once? Apple say do not press it more than once. Anyone know why? Have I killed my Mac by pressing the button too much?

[kakoiken]

I have a similar problem with my Dual G4 1.42ghz. As I was trying to install leopard, my computer froze with an incomplete installation. The only option was to manually turn off the computer by pressing the power button for 5 sec. After this, my computer would not turn on at all without any led's lighting up (power button). Read threads to press the PMU as instructed but that did not work at all. At this point, the PMU was pressed several times throughout the day. Does anyone know a solution?