My iMac keeps turning off

This is a revised from my prev posting.
I'm also having the same problem, I reset the SMU and PRAM twice, following all the advices from this post, but I'm having same issues it shuts down by itself and I have to wait 10 minutes before turning back on again,
Can anyone tell me if they solved the problem and how?
I got the CPU temp monitored at 63-74 C and I have OS 10.5.6
Thanks in advance.

I'm afraid the answer is easy, but not free, fiesold.

Simply put, you need to get a new power supply installed in your iMac.

Rod

I'll add one more person who is experiencing this problem. It started later last month although I don't know exactly what day. My system was delivered with the release of the second generation iMac G5 (May 2005). Originally the problem was that the system would spontaneously restart, but I just changed the software to turn off the 'automatic restart on power loss' and then the system just shut down the next time. This answered the question of whether a software issue was sending a restart command or the machine was experiencing a power loss.

So now that there are many comments on this issue, I am not quite sure on how I separate whether the system needs a new power supply or a new logic board. Or do I just try the cheaper one and hope for the best?

Again, as asked just recently, has anybody had the experience of fixing the problem? And how do we go about getting Apple to consider extending the program if the problem is still continuing to show up as a new problem?

Happy New Year to all,

My 20"iMac G5 ALS has just started having the same symtoms. Tried SMU & PRAM but didn't make much difference. Been to Maplins this morning and bought some compressed air to blow out the insides. Blew out plenty of dust from the lower area (power supply, cooling ducts from the fan end and the exposed fan) Reset SMU & PRAM.
Now powered back up with temps running CPU 52 Deg, 38 Deg Hard Drive.(i use iStat Pro) That's down over 10 Degree. Hope that's worked. Writing this on my iMac. Time will tell.

Neil.
Have noticed may people using 10.5.6. Did problems start after update?
May try downgrading to 10.5.5. if problem reoccurs.

No, the problem was there before the upgrade to 10.5.6. I had actually been hoping that the upgrade would solve the problem (if it were software), but no luck. Let us know whether your cleaning has any impact.
Gershom

Gerson, the logic board problem is generally limited to the first generation models without ALS.

Your problem is a failed power supply. I've experienced it twice myself, with the second instance occuring a little over two years after the first. It's symptoms are exactly as you describe.

Rod

The problem is completely independent of the OS installed, Neil, though sometimes something like a software update , with consequent processor and disk intensive spotlight re-indexing occuring as a result, (and thereby increasing heat and power consumption demands) can make its symptoms apparent.

Keeping things a little cooler may mean that you go a little longer between sudden shutdowns for a while, but the problem will recur and become more frequent with time, regardless.

Rod

Same problem here - on third power supply. Pop then blinking power light. There is an Apple bulletin HT2173. My iMac powers on when I plug in the cord with the back off, then LEDs 1, 2 & 3 come on. Probably try power supply replacement #4. Does anyone know what the significance or 3 LEDs on with #4 off?

i don't know whats going on with this problem, but i started having the same thing happen to me today. if my iMac stays on for longer then 5 minutes I'm amazed. ive reset PRAM and SMU but still not fixed.

I too am another Imac G5 user whose machine just lost total power Boxing Day, it had scheduled on/off times and just failed to come to life on Boxing Day. Think its a power supply issue after reading all info, my concern is the data??? Has anyone suffered data loss due to power supply failure? Or Logic board failure???

Argh! Apple should extend this repair extension. I've got a 20"ALS that is shutting down now. How timely, eh? It's a great workhorse of a computer for the kids.

I've checked the main board on this one, and the caps have the "k" on the top and do not appear to be at fault. I plan on pulling to Power Supply to see what's in there Monday night. :-/

As long as you , or the service people, don't do anything to your HD your data will be safe, brenk.

Rod

Thanks for the reply, after my Imac is restored power wise what would you recommend for backup of mostly iphoto and itunes. I have used Backup Software from Apple on external drives, but am thinking about the iDisk route? Or is this another forum discussion??

What's safest, best, reliable?

Thanks, just waiting to hear if I can get a new power supply from a service centre here in UK.

Hmmm

The best thing to do is get a firewire drive, use SuperDuper! to make an exact clone of your system and then you will be sure that you have lost no data at all.

I agree with Miriam, brenk.

An external Firewire drive (on PPC Macs especially they are MUCH faster than USB2 drives) is the way to go for backups. SuperDuper - http://www.shirt-pocket.com/SuperDuper/ - does an excellent job of creating a bootable clone that can be automatically updated at whatever interval you choose.

Cheers

Rod