Powermac G4 won't power up

[Pat the Rat]

I was given a PowerMac BW G4 400 Mhz computer. I was told it had a bad power supply, but before I buy one (seem to be going for around $60 on ebay) I wondered if there was something else I should try? What is kind of odd is that when I plug it in, the power light stays on without me even pressing the button. I tried holding in the power button for about 5 seconds or so, but it will not go off. It just stays lit. I also tried removing the battery and also pressing the kudo button. No luck.

Just tried popping off the module that holds the On switch from the inside. There were 2 little kudo-type buttons there but pressing them didn't help. The power light remains on constantly, but the computer will not power up at all.

If I do purchase another power supply, do I need to get the exact same power unit (API-9841-291) that is in there now or will any other models work with it?

 

[Pat the Rat]

I bought a PMG4 from ebay for $22 + shipping, but unfortunately it won't turn on either. I"m assuming its power supply may be dead too. Took a chance. It did come with 3 256MB ram chips, though. Is there anything else that would prevent a G4 from powering up? How bout that little battery? I'm guessing it would start but just give the wrong time/date if it were bad? Hoping between the 2 computers I can get one working.

 

[ElDiabloConCaca]

Sometimes the internal battery will prevent a computer from starting normally.

Try replacing the battery (~$5, just about anywhere -- a simple Google search will find you hundreds of places to get them), then resetting the PMU (Power Management Unit):

http://docs.info.apple.com/article.html?artnum=95037

 

[Pat the Rat]

Thanks ElDiabloConCaca, I'll give that a try.

 

[Tinpusher]

I've just replaced my Powermac G4 with a Mac Pro. I therefore have a G4 to cannibalise for spares. Unfortunately, the power supply is dead, I think- I was having the opposite problem in that the power did not seem to be getting through at all.

The long and short of it is that if you want any spares, let me know and I'll see what I can do. I've got 3 x 512MB memory modules in it too, if these are any use.

 

[Pat the Rat]

Yeah, that may be my problem with the ebay unit I have as well. You are very generous to offer parts. Let me see if I can get one running and I may take you up on it should I find out I need something. Thanks!

 

[Pat the Rat]

Unfortunately the battery tests OK, so it is more than likely a dead power supply. So much for the easy fix.

 

[Pat the Rat]

I bought a parts G4 from our university salvage dept for $20 that had a working power supply and transferred the memory, video card, and hard drive to it. It's working just fine. Thanks for all the suggestions folks.