Switching itself off

Hi Rich Brown-

It could be that dust has built up and is causing it to overheat. Anything in the error logs?

Have you cleaned the intake and exhaust vents lately?

Luck-

-DaddyPaycheck

Hi Rich Brown-

I would suggest a vacuum with a wand attachment. Mac unplugged.

There should be a vent along the bottom, one along the top, and some models have a circular vent in the rear that can be partially obscured by the stand when looking for it.

If you have one of the original G5 iMacs you can also open it up and use either a static-free vacuum or a can of compressed air to clean up the fans and ductwork inside.

Luck-

-DaddyPaycheck

I also have the same issue. I have a 20inch iMac Powerpc and I just recently started having this issue. First it was a bad power supply (which was recently replaced), but now it has begun turning itself again. Now that you guys bring up this dust issue, this may be my problem. I do have a lot of my dust in my house and it hasn't been cleaned in a long time. I will let you know if this resolves the issue.

It might be dust... but it is doubtful.

You are probably experiencing the first symptoms of a power supply hardware failure. Checkout www.apple.com/support/imac/powersupply/repairextension/

Well I got a can of compressed air and took care of a fair amount of dust inside the imac. Needless to say it didn't do a thing. I powered it up and within 20 minutes it shut off. The thing is just a few weeks ago I had Apple replace the power supply, and now this BS. Right now it is actually working, but I'm definitely going to have to take it in.

Hi mdkflip-

+"The thing is just a few weeks ago I had Apple replace the power supply"+

That's a warning!

Take it back and have them repair it again. It sounds like the power supply is still causing problems.

Luck-

-DaddyPaycheck

I had the power supply and logic board replaced multiple times on my iMac G5.

Please read this thread which helped solve my similar problem http://discussions.apple.com/thread.jspa?threadID=782405&tstart=0

Thanks.

I started experiencing the same problem a couple weeks ago. The computer will switch itself off, randomly, for no apparent reason. I try to power it up and after several seconds will switch off. It is now working. I cleaned the vents, etc.

I also called Apple Care and was pleased to know I am under warranty for 50 more days. In the meantime, they had me reset the SMU and the accessible memory. We shall see what happens.

However, about a year ago, I couldn't even power it up. Took it in for repair. They replaced the power supply board, etc. Worked like a charm. But like I said, a couple weeks ago started having this new problem of shutting down. I'm going to make an appointment and hopefully get this resolved while it is still under warranty.

I have received some measure of comfort to learn that others have similar problems, but this is bugging me.

The randomness of the amount of time before Rich's Mac powers off, especially since it happens sometimes at startup at the login screen, implies the problem with his Mac isn't due to having the same problem described at that link, which was due to having the Energy Saver settings set to power off the Mac after a certain amount of time.

The most common causes for the problem include:

- a bad power supply, regardless of how recently it was replaced, since Apple uses the same stock of parts for repairs, as for manufacture of the bad computers, until they use up all the original power supplies--the "bean-counter" influence on repair strategy. Usually, defective, leaky electrolytic capacitors are at fault.

- the logic board--here, defective, leaky electrolytic capacitors are also the usual cause.

are you all talking about your computer actually shutting down or just going to sleep? I've been having this problem where my mac is going to sleep whenever i'm doing anything processor intensive like playing games.
it has overheated and shut down in the past but it always gave a warning message first.

Dear all - the contents of previous emails somewhat mimic my own difficulties which are as follows. If anyone can assist I would be extremely grateful:
* I have an Imac G5 17" 1.6GHz, OS X 10.4 Serial No W8511 *PNX.
Its problems are that it shuts down after 40 mins & refuses to start up until some mins later. I have read problems with overheating, bad power supply & logic but am struggling to diagnose which is responsible.

HEAT - I have installed Temp monitor & it shows CPU initial reading 35 C, hard drive 21.5 c. These both rise steadily to cpu 55 c (130 f) & drive 43 c (97 f) after 41 minutes & then shuts down. The 3 fans operate although they do NOT appear to run any faster during 40 mins. I have replaced the drive sensor but no difference. I have installed CHUD & enabled nap feature but no real difference.
I have cleaned the case & vents as best I can inside & out although i can still see dust on fan blades.

POWER SUPPLY/LOGIC - I have no idea.

I hav elooked in system log/console but not sure what to look for. It does say shutdown cause = 2, later Apple SMU shutdown cause = -110 & later shutdown cause = 1.

I have reset PMU but SMU is difficult to reset - removing power cord & inserting whilst pressing power button does not reset time NOR does pressing internal SMU reset button. Removing the internal battery does reset time.

ANY IDEAS???????

Message was edited by: Host