Electric shocks, please advice!

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Thomas Andersson

Hi!

I'm having a problem here that's a bit scary. Often I get electricuted by
just touching the chassis of my computer. I've changed to a new PSU and a
new chassi, but it still happends no matter what combination I'm using.
Leaning over it to fix a cable behind it, just touching it and similar often
results in a bad chock, sometimes even so bad that it shortcuts the computer
and it goes black...
This CAN'T be good for the hardware (I know it's not good for me!).
Anyone have a clue where to start looking for a solution, what ahve I done
wrong in both machines that cause this? Is it related to the PSU, the case,
the motherboard, what??

Best Wishes
Thomas
 
Thomas-

This could be caused by some peripheral equiptment as well. Disconnect all
AC powered peripherals from the computer (Peinter, Speakers, Monitor etc.)
Test to see if the problem is gone. If it is, check the power cords and
reconnect the items one at a time until the problem comes back. If not,
Check/replace the power cord for the computer and Check the wiring of the
outlet that it plugs into. It is possible that the outlet is wired backwards
(Swapping the hot & neutral lines - hmm - this is actually the most likely
cause now that I think about it.)

To test, use a volt meter aet for AC to check for voltage between the case
and a known ground. It should read 0. If it reads 110V - 120v then the
ground to the computer is actually Hot.

Hope this helps.

-Xathros
 
I had a nice long reply typed out then changed my mind as to what advice to
offer..
You posted from a berlin server so I am assuming your on the same 240v
system that we are on here in the UK..
I would test to see how much voltage is coming through the case (test it
with the pc power off).. The problem that we have with our supplys is that
sometimes the earth and neutral will will float apart (yes they do**).. so I
would test the case to a known good ground.. like a metal waterpipe or
something similar.. You could even just test and see if it's wired
correctly.. This is what I would do "last" after checking to see that there
are no skint wires or anything else inside your case.. But if you have a DVM
it's going to be dead easy to just check the Earth&Neutral

(**yes they do)
I have caught mine "floating" by about 11 volts, a check just now shows it's
rock steady.. But maybee I connected the E&N when I replaced my ConsumerUnit
(Breaker Box)..
 
Check the power input cable. When you usually get shocked like that, the
ground pin is open in the power cable or the wall socket.

HVsucks|[PSY-W]ThrasherK said:
*clapclapclap* nice work :)

Heh, sorry, I had to. Anyways to try and help fix:the problem:

1) If you're not getting zapped hard enough to hurt, then you're getting a
5V or 12V tickle from inside of your case. You'd know for sure if it was a
120V blast you got (not to mention your computer would be 100% fried)

2) Pull the PSU from the case, but leave everything else plugged into it.Set
the PSU down on a book or something similar, turn the system on. See if its
the PSU zapping you or if its something inside the case. If its the PSU,
buy a new one (Antec/Enermax or similar) if its inside the case continue:

3) Remove the PSU wires from inside the tower, and examine all of them
closely. if any are exposed tape em up well, or replace the PSU one of the
two.

4) If none of its the PSU, get someone who knows what they're doing to help
you disassemble and reassemble the entire case, as something in your
hardware is directing power straight to the chassis.



--
Mike ''Thrasher'' Kitchenman
Don't ask, you probably don't want to know.
(And if you figure it out, hell I'd be interested in hearing.)
Thomas Andersson said:
Hi!

I'm having a problem here that's a bit scary. Often I get electricuted by
just touching the chassis of my computer. I've changed to a new PSU and a
new chassi, but it still happends no matter what combination I'm using.
Leaning over it to fix a cable behind it, just touching it and similar often
results in a bad chock, sometimes even so bad that it shortcuts the computer
and it goes black...
This CAN'T be good for the hardware (I know it's not good for me!).
Anyone have a clue where to start looking for a solution, what ahve I done
wrong in both machines that cause this? Is it related to the PSU, the case,
the motherboard, what??

Best Wishes
Thomas
Click to expand...
Click to expand...
 
HVsucks|[PSY-W]ThrasherK said:
1) If you're not getting zapped hard enough to hurt, then you're
getting a 5V or 12V tickle from inside of your case. You'd know for
sure if it was a 120V blast you got (not to mention your computer
would be 100% fried)
Click to expand...

Maybe not lethal, but painfull enough :/
2) Pull the PSU from the case, but leave everything else plugged into
it.Set the PSU down on a book or something similar, turn the system
on. See if its the PSU zapping you or if its something inside the
case. If its the PSU, buy a new one (Antec/Enermax or similar) if
its inside the case continue:
Click to expand...

As I said it happends with both my new and old system, or any combination of
them. The old one uses a noname 250W PSU and the new one a brand new Enermax
420W PSU.
3) Remove the PSU wires from inside the tower, and examine all of them
closely. if any are exposed tape em up well, or replace the PSU one
of the two.
Click to expand...

All cables apear to be OK from what I can tell (except one on the old PSU
which I have taped up already).
4) If none of its the PSU, get someone who knows what they're doing
to help you disassemble and reassemble the entire case, as something
in your hardware is directing power straight to the chassis.
Click to expand...

Gonna experiment some toay and see if I can find out additional info about
the problem!

Best Wishes
Thomas
 
have you got a scanner conected to your pc?
Click to expand...

Nope, external connections are ethernet to a ADSL modem, VGA cable to
monitor and line in/out to my stereo amp.

Best Wishes
Thomas
 
Perhaps there is no ground at the outlet, i.e. no connection between the
ground pin and the real ground.

-=-
Alan
 
Hi, you first need to check that your 3rd wire ground lead from the wall
plug is actually connected to earth ground, such as a cold water pipe.
There are testing devices you can buy to find out, or call an electrician.
If you do have a floating ground, this is a potentially lethal problem that
must be fixed ASAP.

BTW, a good quality UPS device should have an internal transformer that will
prevent this sort of problem. I believe they use transformers, not certain
tho.

rms
 
It's not so much the transformer in a good UPS as the fact that the supply
in the ups will charge a large cell/battery.. and then that power is
inverted, and that is isolated (on some not all) ups's..
you quoted me 10 hour later so I am guessing that my post doesnt show up on
every NG, just some.. god bless ntl
 
I would go to a hardware store and get an outlet tester or whatever they're
called. You plug it in the wall and the lights tell you if there's something
wrong. They're cheap.

Have you been using the same line cord? Maybe try another one.
 
spodosaurus said:
Hmm, but as I said this occurs in both my brand new system as well as my old
one, or any combination of the two (cables, PSU etc). I'm gonna experiment
with all external cables today and see if any single one is the culprit.
Click to expand...

Have an electrician check your outlet. Maybe it's not properly wired?
 
I'm having a problem here that's a bit scary. Often I get electricuted by
just touching the chassis of my computer. I've changed to a new PSU and a
new chassi, but it still happends no matter what combination I'm using.
Leaning over it to fix a cable behind it, just touching it and similar often
results in a bad chock, sometimes even so bad that it shortcuts the computer
and it goes black...
This CAN'T be good for the hardware (I know it's not good for me!).
Anyone have a clue where to start looking for a solution, what ahve I done
wrong in both machines that cause this? Is it related to the PSU, the case,
the motherboard, what??
Click to expand...

http://www.hut.fi/~then/mytexts/ungrounded_pc.html
 
Thomas said:
spodosaurus wrote:




Hmm, but as I said this occurs in both my brand new system as well as my old
one, or any combination of the two (cables, PSU etc).
Click to expand...

Same power cable from the wall to the computers? Do you scuff your feet
when you walk?

I'm gonna experiment
with all external cables today and see if any single one is the culprit.

Best Wishes
Thomas
Click to expand...


--

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donate. You are offered the chance to donate only if you match a person
on the recipient list. Call your local Red Cross and ask about
registering to be a bone marrow donor.

spam trap: replace shyah_right! with hotmail when replying
 
Thomas said:
Hi!

I'm having a problem here that's a bit scary. Often I get
electricuted by just touching the chassis of my computer. I've
changed to a new PSU and a new chassi, but it still happends no
matter what combination I'm using. Leaning over it to fix a cable
behind it, just touching it and similar often results in a bad chock,
sometimes even so bad that it shortcuts the computer and it goes
black...
This CAN'T be good for the hardware (I know it's not good for me!).
Anyone have a clue where to start looking for a solution, what ahve I
done wrong in both machines that cause this? Is it related to the
PSU, the case, the motherboard, what??

Best Wishes
Thomas
Click to expand...

hehe it's just static
and yes, it's very bad for hardware (pick up a cpu and it gets a shock, dead
cpu)
just make sure the hardware you are working on, and yourself are grounded
before you touch any sensistive parts
for a pc, you could plug it, but not switch it on (assuming your plug has a
ground pin)
or touch something thats grounded, like a radiator or something
if you work on pc parts a lot, you can get wrist straps and you can plug
into a grounded point
 
What is described could also be an improperly wired AC receptcile or bad surge
suppressor. Get a 3 prong AC tester and check it out before you get hurt.
 
Some of my experience.
I had a VCR connected to my ATi Wonder's video in. And had similar problem
while touching wires behind my PC. Once noticed the TV tuner part was not
working anymore, though the rest was fine. Actually the same VCR was making
this kind of jokes in my stereo rack, but everything is working. Not
anymore -> X files? I should have changed it (it's out off warranty), but
don't think it's worth to buy a new VCR nowadays, even S-VHS ;-)
 
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