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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Desktops > I think my G5 is on the verge of dying....

I think my G5 is on the verge of dying....
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Todd Madson
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May 8, 2010, 02:06 PM
 
Last Saturday, the first of May there was a power transformer explosion in our neighborhood.

It was pretty fierce: there are actually scorch marks in the street from where a component was
arcing up on the pole all the way down the street.

I was mowing the lawn at the time but my wife said the power went on and off about four times.

The transformer in my self-built PC was literally emitting a horrible odor and the thing wouldn't
boot for a day but is fine now.

All of the Macs and PCs in the house are on heavy duty APC surge supressors.

Thursday night about 0130 my G5 2.5 dual went into thermal runaway with the fans at top speed and my cat looking like it was going to pounce on it. Cat has a bed not far from the machine and I'd wager he'd never heard it do that before.

Prior to that this machine has had no problems since the original coolant leak.

I shut it off and went back to bed and told the cat not to worry.

The next morning I booted the machine up and noticed the power supply started beeping whether it was in nap mode or not.
It beeps on and off, sometimes once in a few minutes or several times then stops or keeps beeping like crazy.

It seemed to stabilize later but occasionally it's beeping fairly loudly depending on what is running.

Now the thing seems to beep anytime the machine is under load.

Ugh.

Any ideas here short of replacing the machine altogether (was looking at this fall but not now)?

Power supply will be expensive. I'm guessing the machine took quite a hit.
     
reader50
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May 8, 2010, 02:33 PM
 
Originally Posted by Todd Madson View Post
The transformer in my self-built PC was literally emitting a horrible odor and the thing wouldn't
boot for a day but is fine now.
Transformers don't fix themselves. It must have gotten really hot, but didn't quite short out. The PC worked again after the transformer cooled down. To get hot, it must have had excessive current run through it, which in turn says it was subjected to reduced line voltage.

Under brownout conditions, switched power supplies will pull more current to compensate. Unless they're smart enough to recognize the condition and shut down. From the sound of it, your G5 power supply would also have drawn excessive current through the line-side components. Either some transformer windings are shorted, or electrolytic capacitors overheated and bulged up. Both conditions change their electrical charteristics.

The damage causes the power supply to have a much lower capacity. Loaded conditions call for more power, and the PS has trouble supplying it, hence the beeping. The beeps probably mean the output voltage rails are sagging a little, which the PS interprets as an overload condition.

That's my chain of deduction. If it's right, then you need to replace or repair the power supply, and the rest of the G5 is fine. Bad news is it's a bear to get the PS out of a PowerMac G5. You have to pull most everything including the motherboard before you can get into the PS 'basement'.
     
seanc
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May 8, 2010, 04:49 PM
 
A power supply beeping eh?

Have you definitely tracked the noise to the power supply? Is it beeping or a high pitched whine/squeal when putting the machine under load? If it's the latter, it could well be caps as reader suggested - which caps, depends on the failure mode. Best to get it checked out ASAP, a competent engineer could re-cap that with high quality, low ESR replacements in no time.
If not, listen to the hard drives.

I'd be double checking the PSU in the PC if I were you - bad smells usually equate to things having gotten hot. Just because it still works doesn't mean it's still working properly, you could be missing a diode here or there or have a well baked capacitor. Is it a quality brand?

Make sure your backups of both machines are current and up to date.
     
Todd Madson  (op)
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May 9, 2010, 08:14 PM
 
Update: it's not really beeping, it's more like a high pitched squeal. At times it just does it intemittently but tonight I shut it down altogether
because it was emitting a continuous squeal for minutes at a time - I have my data since I'll just pull the drives out of it.

I'd wager that the caps bulged. Not what I wanted to hear because it's going to be expensive no matter what I end up doing.
Possibly power supply and caps issue.

I was looking to replace the machine in the fall anyway - it's five years old. Putting money into it isn't necessarily what I had in mind.

I will probably have to look at replacing it early. Not a great time for it - I'll have to see what options I've got.
( Last edited by Todd Madson; May 9, 2010 at 08:33 PM. )
     
Todd Madson  (op)
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May 25, 2010, 02:43 PM
 
Update:

The machine seemed to stabilize after 3-4 days of inconsistent behavior but I suspect I now know what has happened: there is some hardware damage after all.

The machine "mostly works" except for one component: the superdrive.
-I can no longer burn cd-r or dvd-r media reliably.
-I can no longer read some media reliably.
-if the PS is marginal, I'd wager the drive itself might be okay but the ps isn't supplying enough to make it burn.
-or the superdrive may have been damaged to some degree when the power transformer on the pole in my area blew.

No matter, this machine is on track for next replacement but it's kind of a bummer that it's been thru so much and comes to this.
I could pop in a new mechanism and see how that goes but if the PS is marginal might not be a great idea.
     
seanc
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May 25, 2010, 02:58 PM
 
More likely that there's a whole load of ripple coming from damaged caps in the PSU which is relaying noise to the laser in the superdrive.
     
Todd Madson  (op)
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May 25, 2010, 08:10 PM
 
Astute assessment. I just need this to hang on for a few more months. If the G5 fails I've got a PC I can use in the meantime...
     
Todd Madson  (op)
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May 27, 2010, 03:27 PM
 
Update:

Last night I began to think that some of these issues were caused by some external issue as at times the thing was working great, and at other times it wasn't.

As I've posted before I have a cat who likes to sleep in a cat cup about two feet in front of the G5 (I guess it likes the fan noise it
makes when the cat sleeps). I think this is a HUGE part of the problem and I will need to put the tower up on top of the desk in
some way or something....

I've been cleaning the machine out about once a month but with the advent of the summer months I think I will need to increase
this to once per week. We have hardwood floors with an area rug in the middle of the room and the tower sits right on top of the
boundary so it's sucking cat hair, carpet fiber, dust and god knows what else is in there.

I opened the machine and it was about twice as dusty as usual and there was a GIANT GLOB of cat hair in the innards that I
had to do a doubletake on it was so big. It definetely wasn't there eight days ago. I can't believe how dusty it was in there.

I got out the compressed air and really did a thorough cleaning.

The machine not only worked better after that but I was able to burn discs again and I wonder if the dust and debris was
causing some kind of weird short - I also replaced two of the ram chips that I suspected were suspect.

Temps are back down to normal and the machine is running well (for now). I don't pretend that it didn't sustain damage that
would have it fail spectacularly.
     
Mac Write
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May 27, 2010, 09:16 PM
 
If your stuff in your house sustained damage due to the power company, get them to pay for repairs. If your surge protecter failed to work, they normally have a $XX,XXX insurance policy that should cover the damage.
Get busy living or get busy dying
--Stephen King
     
Todd Madson  (op)
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May 28, 2010, 01:31 PM
 
Mac Write: thanks for the tip! I'll look into it. I know some of the houses near mine had small fires as a result. We didn't have fires but some appliances may have experienced serious amounts of power, more than they were designed to deal with despite being on surge suppression devices.
     
   
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