09-09-2011, 07:43 PM

Hey, folks. This is regarding my dearly beloved Dual 1GHZ PPC G4 running OS 10.4.11.

Every once in a great while (like, every two months or so) my computer will shut off for no reason. This never seems to happen when I'm around; I'll return from work and it will be off when I'd put it to sleep before leaving.

When I try to turn it on, it starts to boot and then shuts off before the monitor even comes on.

When I try to turn it on again, it won't even start to boot unless I switch the power cable to a different outlet on the same power strip.

I can switch the plug back and forth between two outlets as many times as I like and get the same result, but I can never get it to start booting twice in a row from the same outlet.

At this point, I have to leave the computer alone for a few hours. When I return, I am able to boot it in safe mode, perform /sbin/fsck -fy, and then reboot it successfully.

This isn't an urgent issue, but I'm curious to hear any theories. I would hate to ignore the situation only to one day have my computer fail to turn on ever again.

09-09-2011, 07:56 PM

Try a PRAM reset: Resetting your Mac's PRAM and NVRAM

And a SMC reset:
1. Shut down your Mac
2. Disconnect the power cord
3. Press and hold the Mac’s power button for 5 seconds
4. Release the button
5. Reattach the power cables and boot the Mac as usual

09-10-2011, 03:08 PM

Thanks! I had reset the PRAM recently but I did it again along with the SMC reset. I guess I won't really know if it worked unless the issue reoccurs which, hopefully, it won't!

09-10-2011, 03:23 PM

If it does it again after trying what MacDude suggested, it sounds like a power supply issue. When you unplug and plug back in its causing it to work again. Could be the 28VDC that Apple uses for startup. If that voltage goes away while in Sleep I have found at least with my Power Mac G4's that it will shut down.

09-11-2011, 10:24 AM

dtravis7, can the power supply issue be dealt with indefinitely by doing an SMC reset every time? Or should I start looking for old power supplies and instructions on how to install them myself? The last time I took this computer to an Apple specialist they told me it was an antique and they couldn't order parts for it.

09-11-2011, 11:10 AM

I would turn off sleep mode until you find the issue. Make sure you have a good battery and your firmware is up to date for that model. You can buy any thing on Ebay...just search your model G4 or power supply serial number.

09-12-2011, 02:00 AM

Originally Posted by carcass

Or should I start looking for old power supplies and instructions on how to install them myself?

Yup.

Or find a local specialist like I did.

But...G4?!?! Sorry to be harsh, but that's just too old, it would be silly to fix that. You can get a G5 on eBay for maybe $200 (roughly the same as an installed power supply), and a Core 2 Duo 2.16 for $400 (which I can tell you is WAY faster).

[...er, that's in iMac-land, not tower-land. But still...]

09-12-2011, 07:57 AM

Originally Posted by carcass

dtravis7, can the power supply issue be dealt with indefinitely by doing an SMC reset every time? Or should I start looking for old power supplies and instructions on how to install them myself? The last time I took this computer to an Apple specialist they told me it was an antique and they couldn't order parts for it.

I used to have an iBook G4 and had exactly the same problem. It turned out to a damaged core of the LV charger/PSU cable on the Mac side. I couldn't really work out what was going on until the insulation started to wear through and exposed the damaged multi-strand. I guess it was ham-fisted storage and cable winding that caused it.
You mentioned that it wouldn't reboot until you switched the cable to a different mains outlet..which perhaps means that you are temporarily and unwittingly reconnecting the circuit.
Check your cables...it may be much simpler than you think and surely your local Apple Store will be able to supply a new charger/psu off the shelf as I managed to get one only nine months ago and I'm in the UK!

(Apologies I meant an iBook G4 which is a different beast..)

09-12-2011, 12:10 PM

Well, the update is that now leaving the computer asleep for more than a few hours results in this issue. I can't leave it on all the time because then I can't sleep (it's in my room and I'm a light sleeper).

So is it the general consensus that, failing the PRAM and SMC resets, it's probably the power supply?

Sorry to be harsh, but that's just too old, it would be silly to fix that.

Ha ha, no offense taken. And, yeah, I looked up power supplies and they were pretty pricey. I do have an old model G5 that doesn't work but, in about three weeks, I'm going to be able to take it to a friend who's pretty sure he can fix it. I just need to keep this machine running until then!

Thanks again for all your help, everyone; even if it was just speculation.