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Possible: Mac Pro Shorting Out Devices?
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Moogs
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Join Date: May 2004
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2012-01-17, 13:56

So over the last year or so I've started to lose some devices (hard drives mostly but other behaviors as well) and I'm wondering if it is possible (in the physics / electricity sense of the word) for a problem inside the computer on the main board... to cause other devices connected to it to behave unusually or short out / get fried at random times?

Some evidence (just not sure of what):
Two hard drives that were connected via FW ports 400/800, one purchased as external (G Drive) one an internal drive I added to an OWC enclosure, that both stopped working within a few months of getting it, both with the click of death.

Bumping my computer by accident with the "wheel arm" of my chair causes the screen to temporarily go black / show static lines before coming back after maybe 1 second

Apogee Duet (or maybe microphone) that no longer seems to work except ISFA iTunes playback, which was also plugged into Firewire but on the front side of the Mac instead of rear ports.

It is getting to the point where I'm worried that I'm throwing away money on anything I connect to this machine / should get a new one.

It is plugged into a APC battery backup (1500 watts so no issues there AFAICT), although the APC thing is not grounded by connecting that extra wire to the outlet etc (there was some kind of funky instruction for optional safety but I didn't want to screw with it). So it's Computer > APC > Outlet. No other major gadgets plugged into that outlet, etc. Any ideas?

...into the light of a dark black night.
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Dave
Ninja Editor
 
Join Date: May 2004
Location: Bay Area, CA
 
2012-01-17, 14:59

Quote:
Originally Posted by Moogs View Post
So over the last year or so I've started to lose some devices (hard drives mostly but other behaviors as well) and I'm wondering if it is possible (in the physics / electricity sense of the word) for a problem inside the computer on the main board... to cause other devices connected to it to behave unusually or short out / get fried at random times?

Some evidence (just not sure of what):
Two hard drives that were connected via FW ports 400/800, one purchased as external (G Drive) one an internal drive I added to an OWC enclosure, that both stopped working within a few months of getting it, both with the click of death.

Bumping my computer by accident with the "wheel arm" of my chair causes the screen to temporarily go black / show static lines before coming back after maybe 1 second

Apogee Duet (or maybe microphone) that no longer seems to work except ISFA iTunes playback, which was also plugged into Firewire but on the front side of the Mac instead of rear ports.

It is getting to the point where I'm worried that I'm throwing away money on anything I connect to this machine / should get a new one.

It is plugged into a APC battery backup (1500 watts so no issues there AFAICT), although the APC thing is not grounded by connecting that extra wire to the outlet etc (there was some kind of funky instruction for optional safety but I didn't want to screw with it). So it's Computer > APC > Outlet. No other major gadgets plugged into that outlet, etc. Any ideas?
Can you elaborate on "not grounded"?

Also, see if wiggling the monitor cable does the same thing as bumping the computer.
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alcimedes
I shot the sherrif.
 
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2012-01-17, 15:40

Yeah, the Not grounded part is what would be the most interesting. If it's truly not grounded at all, then that might explain the shorts etc.

Has anything ever fried that wasn't connected to a firewire port at some point?

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Bryson
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Join Date: Feb 2005
Location: The Canadark
 
2012-01-17, 15:58

Yeah, this sounds like a grounding potential difference. When you say teh APC is not grounded, can you elaborate? Does it have a three-pin or a two-pin plug? The Mac Pro should definately be grounded (it has a metal case!) so you should resolve that ASAP.
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Ebby
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2012-01-17, 16:57

I have a similar setup for the past 10 years, now with the same UPC and Mac Pro, and that grounding light has always been on but I never lost a device from anything other then my own stupidity. It is my understanding that, while my home is not grounded (not wired for it), the electrical devices all share a common ground together through the APC so there is no voltage difference between devices. The system floats a few volts but that is for everything plugged into that circuit. I did go under the house years ago and added my own grounding strap, but it doesn't seem to do much at all.

Should I take another whack at it as well?

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Bryson
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Join Date: Feb 2005
Location: The Canadark
 
2012-01-17, 17:19

Well, there's two issues:

1: if the ground is floating then if (and it's a big if) they all use the same reference ground then you should be OK on a day-to-day basis. But if one of the other devices in plugged into a different outlet, then you have some real potential* problems.

2: More seriously, if there's an electrical fault somewhere, you have no protection: the metal case of the Mac Pro could become live and very dangerous. With no ground you'll have no GFCI protection and so no way to know there's a problem.

You say your house is not grounded at all? Is it a boat? I seriously doubt that's acceptable these days. I'd ask for a real electrian's opinion, if I were you. (I'm a very specialized type of electrician, but most of the general principles apply.)


*=Pun intended
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Ebby
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2012-01-17, 21:45

All devices from the wall minus one halogen lamp share a common "ground". Our house is the very last one on the transmission line and the wiring is so old there literally IS NO third wire.

We strap the ground for newer plugs to water pipes and such or run a dedicated ground back to the electrical box. But only if the original plugs die or, more common, run into 2-prong/3-prong issues or that &#(@ polarized end nonsense until we throw up our arms and say we had it! Haha! The kitchen was the first to be converted. Our house is not a new one

Quote:
More seriously, if there's an electrical fault somewhere, you have no protection: the metal case of the Mac Pro could become live and very dangerous.
We have a rule in our house... Don't use anything with power and bear feet in the garage. Ground is quite literal there and even a few volts gives you the tickles.

^^ One more quality post from the desk of Ebby. ^^
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alcimedes
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2012-01-17, 21:57

Given what you've just described, I'd say it's highly likely that it's shorting stuff out, and yes, it might in fact be dangerous. Is it strictly limited to 1394 devices though?

Were all of those devices plugged into a different outlet, or part of the same UPS?

Also, I thought the grounding on the UPS devices didn't function if the outlet they're plugged into isn't grounded properly, but I could be wrong there.

Google is your frenemy.
Caveat Emptor - Latin for tough titty
I tend to interpret things in the way that's most hilarious to me
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Dave
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Join Date: May 2004
Location: Bay Area, CA
 
2012-01-17, 23:24

Quote:
Originally Posted by alcimedes View Post
Also, I thought the grounding on the UPS devices didn't function if the outlet they're plugged into isn't grounded properly, but I could be wrong there.
The UPSs that my computer's hooked up to will work without a ground pin, but there's a "wiring fault" light/beep.
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Moogs
Hates the Infotainment
 
Join Date: May 2004
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2012-01-17, 23:30

Maybe my APC is grounded, I'm not sure. The plug is a heavy-duty three prong model and they're all going into standard outlet. What I thought I remembered was that in order to ground I had to run an extra wire or something into the outlet? Maybe that was for older homes without the three prong thing or something.

House is about 10 yrs old so definitely not the case of ancient electrical code or anything like that.

Also yes I believe all the devices were plugged into the APC unit at the same time as the Mac Pro and not another outlet, etc. Possible one of the outlets ON the APC is frying things??

...into the light of a dark black night.
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