Re: G4 Won't Turn On

I accidentally turned off my UPS when my G4 was in sleep mode last night. When I went to turn the G4 on this morning it would not turn on. The power switch lights breifly when I push it in, but nothing happens. I tried the reset button and also holding the on/off switch in for about 10 seconds (the power light remains lite while doing this), but again the computer is silent. Does anyone have any ideas to get my G4 running OS 9 to boot up?...Thank you.

Phil....

Hi Phil,

Don't know, have never heard of this. Might be time to call for tech support.

--ken

I found a solution through a friend for this problem and I'm posting it in case it will help anyone in the future.

Open the side of the G4. On the Mother board, right next to the small cylinder shaped battery, there is a small switch. Press this switch. I did this and was able to power up my G4 after that.

Phil

Good news.

--ken

The procedure is called restting the PMU (Power Management Unit). On G5s, it's called the SMU (System Management Unit).

-DH

hi
I've had similar problems with both a G4 and a G5, where the startup was inconsistent, would balk then finally work, sometimes hang on booting, then one day nothing at all. Both had to have their power supplies replaced.

My total-guess suspicion is that the power supplies are kind of marginal, without much headroom, that the computers are hard on them, and as they wear the voltage sometimes just doesn't get there, causing funny software-looking problems.

The G4 was running an old Pro Tools with OS9, would often hang on the boot process while loading extensions, always right at the end. No one could fix it. I got thru a long and painful period until my next rig by keeping the OS and Didgedesign install discs handy and just re-installing on any given morning. It finally did what happened to you; would kind of light for a few seconds, then go dead. At the end it also made a weird loud shreaking sound.

The G4 took nearly two years to finally quit entirely, during which time I took it to 'experts' several times who all blamed the software. This problem was never really diagnosed and resolved until the power supply was recently fixed. Still using it, so far it seems ok. Could be the software hang could return, I suppose, but it hasn't yet for the last few weeks, a long time compared to before.

My G5 warranty had been expired for about a week when it stopped working. To Apple's credit, they went ahead and replaced it for free.

good luck
g