Worrying about the Health of my iMac

mr. k

mr. k

Registered
I have a very reliable computer, my iMac. And it's been acting very funny of late. A few days ago my I came home one night and my mom started talking about how one of her work documents was "eaten line by line from the bottom up," which I took for heresy because I messed around on a document for a while and couldn't duplicate it.
But today I got on the computer after school, read a little and played some, got off about a half hour later and didn't come back for a few hours. I don't think that in the time I was gone anyone used the computer. But when I came back and it was shut down and I pressed the button a few times and it wouldn't turn on.
I waited a bit and came back to turn it on and it did, but somehow my system was all goofy. The date was Wednesday, December 31, 1969 (it
s Tuesday Febuary Third... 04) and I checked /var/log/system.log and found a few nice lines:
Code: 
Dec 31 18:00:06 localhost kernel: ApplePMU::PMU FORCED SHUTDOWN, CAUSE = -127
Dec 31 18:00:06 localhost kernel: Local FireWire GUID = 0x393ff:0xfe0d67d6
Dec 31 18:00:06 localhost kernel: ApplePMU::CLOCK RESET!  PMU WAS PROBABLY RESET SOMEHOW!!
and I was just wondering: How would my computer crash (maybe the power cord got disconnected by my dog - but I doubt it) and reset the PMU, and what does CAUSE -127 mean?
 
And I just checked it out a little at info.apple.com and it looks like when the PMU is reset it wipes PRAM and NVRAM and also any ram disk with information on it, as well as shutting down your machine. So it looks like I have the cause of the shut down - but what would cause the PMU on a 600mhz G3 slot-loading iMac to reset itself? I guarantee you I haven't opened the case to this baby since I got her a few years ago, I don't think we have ever had it looked at by professionals... This is wierd - maybe some electrical surge? My power didn't go out, and I don't think that a dog chewing a cord would reset the PMU. And I turned the machine on without jiggling the power cord. Anyone know what this could be about?
 
mr. k said:
My power didn't go out, and I don't think that a dog chewing a cord would reset the PMU.
Click to expand...

Whoa, if that dog chewed far enough through the cord to cause a short or spark, that would most definitely be a cause to think that the PMU had been reset. I would rank animals chewing through cords as a number two cause for power problems with a computer, just short behind number one: electrical surges. That is most definitely a bigger problem than you're thinking it to be!

At any rate, you may want to check the internal battery. Internal batteries drained of their power can make a computer exhibit strange behavior, like the inability to start up, video problems at startup, date/time resetting and other problems. You can find many batteries for your computer at Radio Shack or online, possibly.

Check here for battery part numbers:
http://docs.info.apple.com/article.html?artnum=86181
 
oh, no the dog couldn't chew through the cord ( I hope... ) but she has been getting under there and perhaps she yanked the cord out of the socket enough to cut the power to the computer. But I still don't think that that would cause a PMU failure...
Well it really isn't that hard to look into something yourself is it...
from http://docs.info.apple.com/article.html?artnum=9805
-127 fsDSIntErr Internal file system error
SO a filesystem error caused my PMU to go wild? I don't like the sound of that...
 
El Diablo is most likely correct in that the battery is probably weak. The iMacs rely on this for many things and a weak one can cause havoc on the logic board which in turn may cause a file system error or a bad pref file to be written or updated.

I would get the battery replaced and reset the logic board with the Open Firmware commands (option-command-O-F at boot):
reset-nvram
reset-all (will cause a restart)

This should clear any pram/nvram errors and then run Disk First Aid from a boot disc other than your HD. Also run permissions while your at it.

Hope this helps,
Mikey
 
Ok, thanks a bunch guys. Maybe this will just turn into an excuse to get a new computer... I think I'm gonna start nightly backups though :)
 
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