[Todd Madson]

If you remember some months ago my power supply fan died.

I was unaware it was truly dead until I noticed by a utility that
the temperature was up over 120 degrees inside the case, probably
more and it probably was that way for weeks on end.

I replaced the system fan and all systems were go again.

Now tonight I really think the system is having big problems.
I was having repeated crashes where the system would hard lock
and I would get a repeating 2 second audio byte from whatever
MP3 I was playing in either iTunes or Quicktime.

Tonight when I tried to reboot the system simply wouldn't come
back up.

I powered the machine up, the power supply fan and the internal
system fan moved the blades just the merest amount and stopped.
No lights no sound no power.

Removed extra ram, went back to original Apple ram, put in original
ATI Rage 128 Pro and crossed fingers. Nothing. No lights, no sound
no power except for the fan moving slightly.

Talking to my buddy Paul he and I came to the conclusion that we
believe the power supply is shot.

My ram also may be potentially compromised given the crashes with
the repeating sound deal (see the OS X forum here for that thread).

Worst case scenario the CPU or a motherboard component might be
at fault too.

Luckily I have a PC I can access the net with but it's not OS X.

Any ideas on sources for power supplies?

If replacing the power supply doesn't do the trick I might have to
see what I can do to replace the box altogether. An ugly thought
but I don't want to keep throwing money at it until it works.

Anyone run into anything like this?

Anyone have sources on used or refurbished systems if the thing
proves to be a money pit?

[Spliffdaddy]

I'd suspect the powersupply is dead. This could have been causing your lockups if the voltage was not being tightly regulated. RAM draws a lot of power - more than the CPU does if all your slots are filled.

Remove the powersupply and take it apart. Look for burned components. Of the last four dead ones I've taken apart, three had obvious damage - but only one of them smelled burnt.

Replace the powersupply and see if all is well once again. Personally, I would buy a decent ATX powersupply and splice-on the Mac connector. An Antec 350watt would be a good choice ($50-ish). The temperature-sensing fan is typically almost silent.

Chances are pretty good that the rest of your hardware is unharmed.

[Deal]

usually a processor will shut down before it gets too hot. I would try the new power supply. It could cause all the problems you mentioned. As for where? Try this place: http://www.sunrem.com/

Check the price at an Apple dealer. On some parts you get them cheaper for sending in the old part. Parts from Apple are not cheap though.

Good luck

[D'Espice]

You can use a normal ATX power supply for your Mac, you just have to cut the white wire, because the Apple logicboards need ground there yet the ATX power supplies have -5V.

Before you do it though tell me, then I have that written down somewhere and will look it up to be 100% sure.

[Todd Madson]

Sun Remarketing didn't have any G4 power supplies.

I could go for an ATX style power supply but then I would have
to deal with the hassle of the wiring harness involved - does
anyone have definitive info on this?

Maybe a mini ATX style supply? Preferably it would fit in the
case.

We have two cats and the idea of having a power supply outside
the case just isn't terribly good since they nose around
everywhere. Hate to see a shocked cat.

Any idea on where else to get power supplies? I looked at small
dog systems but they also didn't have any at the time I looked.

The other issue I'm concerned about is that if I see the issue
where the sound locks up. If that happens I might as well sell
the damn thing for parts and start saving for another G4 tower
since I don't want to replace 1.5 GB of ram, hard drives tossing
money into a pit with no end.

[suhail]

I had a similar problem with a client's computer, where nothing happens when he pushed the power button.

All we did was discharge the reserve power, and everything worked again.
To do that there is a tiny microswitch on the motherboard, usually next to the battery, press it. Then try booting up.

I hope this works for ya!

[Deal]

Yea, that's called resetting the power manager. It is worth a try. Also, if that doesn't work, pull the battery out and let it sit (for a couple hours even) then put it back in and try it. Also make sure you pulled all unnecesarry peripherals. All USB, Firewire, and any non-stock PCI cards. Also go down to one stick of RAM (use the Apple stock RAM). It's worth a try.

If you want to get an Apple powersupply in Minneapolis call FirstTech. 612-374-8000 and ask for Rob Boytz. He'll hook ya up.

Once again, good luck.

[Todd Madson]

Resetting the power manager didn't correct the problem.

I'm likely going to take a look at the replacement power supply option.

Ouch. $250 is what it would set me back.

[Todd Madson]

The G4 boots if my 80 gig hard drive is not connected. If the
drive is connected, it refuses to boot. Most curious - my guess
is the power supply had its components damaged with the excess
heat and isn't producing a full power load. Hum. I have some
ideas, stand by.

[Todd Madson]

The G4 is back among the land of the living but I cannot believe what
apparently fixed it.

I moved the 80 gig drive from the bay below the DVD drive to the
bay in the bottom of the machine next to the 10 gig drive already
there.

For whatever reason it's running and has been for two hours at
about 96 degrees.

While I was out I picked up a new fan for the G4's power supply -
it's a lighted fan with a thermal sensor that will kick up the fan
speed from 2500 rpm to 4000 rpm if it gets hotter.

More news as it develops, I'm just glad the machine is back up and
running.

[jonn804]

Originally posted by suhail:
I had a similar problem with a client's computer, where nothing happens when he pushed the power button.

All we did was discharge the reserve power, and everything worked again.
To do that there is a tiny microswitch on the motherboard, usually next to the battery, press it. Then try booting up.

I hope this works for ya!

thank you. this restored my G4 premature death