Instant Shutdowns on iMac G5 PPC 20" HELP!!!!!!

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Level 1

10 points

Instant Shutdowns on iMac G5 PPC 20" HELP!!!!!!

i have recently experienced what i think is a PSU problem. BUT i want to see if there is anyone else with my problems. I have been using my mac for about 7 months now and just today i experienced 3 instant shutdowns. no warning, no sound. just immediately off. i tried to turn it back on but no luck. so i unplugged the cord from the wall (making sure its seated correctly) and then turned it on. It works! great!! BUT then while burning a CD again it turns off! its not a power surge becuase nothing in my office is affected. its not the cord because its seated correctly, and its not a first gen imac that has been recalled for the PSU. i cant figure out what it is. if there is anyone that may have some info or is experiencing these problems please respond. Thanks in advance!!!

iMac G5 (iSight) 20" 2.1Ghz PPC, Mac OS X (10.4.6)

Posted on May 31, 2006 12:57 AM

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Answer 1

Rod Hagen

Level 7

32,000 points

May 31, 2006 6:04 AM in response to ADIOlab

ADIOlab,

Your symptoms almost certainly indicate a failing power supply unit (PSU), I'm afraid. I've been through this myself.

These are actually quite common with the "Second generation" iMac G5's too, (though fortunately these don't suffer the common motherboard problems experienced by the "first generation".)

The PSU will have to be replaced to fix it.

Rod

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Answer 2

May 31, 2006 9:22 AM in response to ADIOlab

Rod's right, it's almost certainly the PSU. I had my power supply replaced for the same thing about a month ago. Also, I've seen the same symptoms on G5 towers, and new power supplies fixed it there, too.

If you are really curious, you can open the Terminal application, type in the following command, then hit the "enter" key:

<pre class="command">dmesg | grep -i shutdown</pre>You'll most likely see a negative number, like "-110" or "-122":

<pre class="command">AppleSMU -- shutdown cause = -110</pre>A clean shutdown or reboot results in the number being positive, like "1" or "2" or "3"...

charlie

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Answer 3

MGW

Level 7

27,047 points

May 31, 2006 11:53 AM in response to ADIOlab

Yet a third vote for PSU failure, however, you should also make sure that you have backed up your data as soon as poossible, I recommend SuperDuper!, whcih is a versatile app that will allow you to make a clone of your Mac, as well as perform scheduled backups. Call Apple asap, things will get far worse the longer you let the failing PSU operate.

Do post back and let us know how you made out,
Miriam

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