iMac DV Spontaneous Shutdowns

zebulon303
zebulon303 used Ask the Experts™
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I'm running MacOS 9.1 on an iMac DV 400mhz. The system has been mostly stable, but in the last couple of days I've had 3 sudden unexpected shutdowns.  The first two were as if someone just pulled thte power plug.  The last time though, it just immediately came back on and saved the state it was in.  The power did not surge, or at least it did not seem to as the desk light attached to the same surge protector strip did not even flicker.  I was using different applications each time, once Word, the other Eudora.  
Is an early sign of some hardware failure? I've checked the power cable which was firmly in place in the back of the mac, and to the outlet.  Any ideas or suggestions greatly appreciated!
Lon
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It probably was a voltage drop. I've had similar things happen here and it turned out everyone in the neighborhood had their computer shut down at exactly the same time. The lights didnt flicker, but computers certainly had issues with it. Now, you say the power cable is going from the computer to the wall. BBAAAADD idea. All desktop computers need a surge protector. Get one. The cheap ones do nothing so youll have to spend some bucks but its worth it.

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Commented:
Thanks for the response.  It is worth trying to find out if anyone else had the same thing happen in the neighborhood.  

I'm sorry if it was not clear but I actually did state that the Mac was connected to a surge protector.  I would suspect that it was the fault of  cheap surge protector, but one of the times it was connected to a decent quality one.   I've heard surge protectors vary a lot in their ability to actually protect against surges.

Any other suggestions out there?  
Lon
See if it happens again. My guess is still that youre having a "brown out" which is just enough of a voltage drop to shut down your computer.
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Commented:
This can also be a sign that the Down Power Converter or Analog Video Board are going. If you notice the screen acting funny (geometry or color) is probably the Analog Video Board. The Analog Video Board is what you see through the clear plastic of the iMac. It is responsible for high voltage, both for raster and as power supply. It also sends power to the Down Power Converter. It's responsible for the 12volt for the rest of the system.

If your power is flickering, a surge protector will do very little. An Uninterruptable Power Supply (UPS) will be needed to smooth out Brown Out conditions. An APCC brand Back UPS 500 should do the trick.

Author

Commented:
Thanks for both the comments.  I appreciate the info.  It has not happened again yet.  I'm not sure what it was.  I guess I'll wait a see a bit longer.  I'm not sure about awarding points, since I can't really tell who has the right answer.  If nothing turns up, I'll split the points between you guys I guess.  Thanks!
Lon
Hi, I'm not sure if you solved your problem yet, but I had this exact problem and went through all the same power unit suspicions.
However, in the end it was a 'sticky' power on button on the front panel of the iMac!
Not 'goo' sticky, but plastic against plastic sticky.
What I ended out doing to resolve the problem was to flick it "the bird" a few times! Yep, a few sharp flicks on the button seemed to have loosened it enough that it did not shut down any more!

This is the only time I have been abusive to my iMac! But I guess it was stepping out of line just a little too much.

PS: We have since made up and continue to have a productive relationship. :)

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