iMac G5 won't power on but does wake up?!?

[mugatu]

Hi,

Im a long time browser of these forums but this is my first post.

I have an iMac G5 that recently has been having some problems. Often pressing the power button doesn't start the machine up, although trying again 20 minutes later does. Yesterday I couldnt get it to power on at all so I removed the back panel and tried to power it up using the internal power button. No luck. The first LED on the logic board is lit but the others will not light.

I was starting to think my logic board must have gone (after only 2 and a bit yrs) but strangely this morning the iMac woke itself up (I have an itunes alarm program installed that boots the Mac at 7am) with no problems.

Anyone got any ideas? I'd really appreciate it! At the moment I've had to resort to setting a schedule so it auto powers on at times when I think I'll need to use it!

Thanks in advance

 

[mad jew]

Weird. Maybe try resetting the SMU.

 

[mugatu]

Thanks for the reply. Yea, I already tried resetting the SMU on the logic board, but didnt seem to make a difference.

Thanks anyway. Any more ideas?

 

[mad jew]

Okay so it's an original iMac G5. This sometimes works for problems like this... Reset the SMU and then leave it unplugged from the power overnight. See how it goes from there.

 

[mugatu]

Thanks, will give this a go tonight.

 

[snavey]

Back up now! My iMac G5 rev b started acting up a couple of weeks ago - lots of fan noise - root tasks using 100% cpu, waking itself up from sleep, etc.. it would restart after cooling down until two days ago. I've tried leaving unplugged (resetting SMU) and pulled the back off to test power supply. According to apple's help page the logic board is fried - Just over two years old. Right now I'm typing on an ibook that's approaching 6 years of abused use. the desktop g5 never moved from its desk. Needless to say, I'm not pleased. . . nor do I have apple care. . . ..I'm meeting with a "genius" tomorrow.