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Weird Rev A iMac G5 Issue


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Weird Rev A iMac G5 Issue
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bassplayinMacFiend
Banging the Bottom End
 
Join Date: Jun 2004
 
2005-11-03, 08:05

Here's a short history of my iMac troubles. Last July my iMac started spontaneously putting itself to sleep. In August, the Apple store Westfarms replaced the lower fan. The fan replacement didn't solve my problem, so I brought it back to Westfarms last week.

Why the long wait you ask? I was recovering from foot surgery so it was difficult schlepping around a 45 lb. iMac on one good wheel when the other is in a cast.

Anyway, Westfarms replaced the logic board. Brought it home, turned it on and within 20 minutes my iMac spontaneously shut down. Great, I thought, I've been upgraded from spontaneous sleep mode activation to spontaneous shutdown. With a nice loud POP to announce the shutdown no less.

So yesterday, Westfarms informed me that my iMac passed all their post logic board replacement tests. So, they wouldn't allow me to bring in my iMac for repair (???). I called up AppleCare and supposedly their onsite contractor is going to call me today to set up an appointment for an onsite visit.

Well, I got to playing around with whatever fixit attempts I could do at home. I reset the SMU (the little switch on the mobo), did the reset-nvram, set-defaults, reset-all in open firmware and did fsck in single user mode. Oh yea, I reset the PRAM too.

This is where it gets weird. If the fans are acting normally (controlled by OS) then I can expect the POP noise and spontaneous shutdown to occur within a few minutes of booting my iMac.

IF, however, I boot into single user mode and issue the 'shutdown -r now' command, my iMac reboots, but OS X doesn't control the fans, so they are at full speed all the time. In this case, I don't get spontaneous shutdowns. Once I unplug my iMac for a minute, then plug it in and OS X controls the fans again, I get the POP shutdown thing happening again.

So, I'm happy that I have a workaround so I can use the iMac until it gets repaired again, but it just seems weird I could do this. It's also quite headache inducing to listen to the fans going at full RPM while trying to play Age of Mythology.
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bassplayinMacFiend
Banging the Bottom End
 
Join Date: Jun 2004
 
2005-11-03, 09:15

Well, it looks like the fans running at full RPM is a 10.4.3 specific issue with other owners as well. So it looks like I'm exploiting a bug in the latest OS X in order to keep my iMac running. I'm still waiting for a call from the onsite contractor to set up an appointment for them to look at my iMac.
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bassplayinMacFiend
Banging the Bottom End
 
Join Date: Jun 2004
 
2005-11-16, 09:18

My problem seems to have been resolved with a power supply replacement. So far so good!
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Engine Joe
Going Strange...
 
Join Date: Aug 2004
Location: Brooklyn, NY
 
2005-11-16, 09:53

The Rev A iMac G5s seem to have lots of problems with the power supplies - whether yours or the burn-out problem...
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