Computer case is shocking!

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When I touch the computer case, I get a small shock even though the computer
is turned off but still plugged-in. When I look inside, I see a small light
that is lit.
The computer is resting on 2 bricks. The computer seems to be working OK
although the video intermittantly goes "black" briefly. The screen blanking
briefly only occurs when I use a particular video card. When I use the other
video card, the screen never blanks. Should I be concerned about the shocks I
get?
 
b11_ said:
When I touch the computer case, I get a small shock even though the computer
is turned off but still plugged-in. When I look inside, I see a small light
that is lit.
The computer is resting on 2 bricks. The computer seems to be working OK
although the video intermittantly goes "black" briefly. The screen blanking
briefly only occurs when I use a particular video card. When I use the other
video card, the screen never blanks. Should I be concerned about the shocks I
get?
Click to expand...
You have either a card, power supply, or motherboard that is leaking
power to the case. This is not how they should behave. You could try
removing all the cards from the case and see if you still get shocked.
If so then try a new power supply. If that still does not fix the
problem you will have to check the motherboard to see if it is
improperly installed or faulty.
 
You may be feeling a Static Spark. If that is the cause - be very carefull
not to touch anthing inside the case without touching the metal case first.
You could damage any of the electrical components. If you are walking on a
carpet it builds static electricity in your body then discharges when you
touch your computer case.
 
Could also be static electricity, especially if you are walking across a rug
to get to the computer. On way to prove this is to touch a wall switch plate
or outlet before you touch the computer.

JS
 
When I touch the computer case, I get a small shock even though the computer
is turned off but still plugged-in. When I look inside, I see a small light
that is lit.
The computer is resting on 2 bricks. The computer seems to be working OK
although the video intermittantly goes "black" briefly. The screen blanking
briefly only occurs when I use a particular video card. When I use the other
video card, the screen never blanks. Should I be concerned about the shocks I
get?
Click to expand...

Having a small light on inside when it's "off" is normal. You just
turned it off from the front panel. If you used the power switch on
the back that light would go off. That light is there to warn you the
board is still hot (hot in an electrical sense, not a thermal sense)
and not to mess with the hardware--I know someone who blew some stuff
that way on a board that didn't have the little light.

The voltage involved is not enough to give you a shock even if it was
shorted to the case, the shocks must be coming from something else.

Since you can get a shock from the case it pretty much proves the
ground circut isn't working. You're either not connecting the ground
somewhere in it's source of power or you have a miswired house. (I've
seen this before in older houses--three-wire plugs with the ground
plug not connected to anything.) If the ground isn't hooked up I
could imagine the fans building up a charge that's giving you a shock.
 
b11_ said:
When I touch the computer case, I get a small shock even though the computer
is turned off but still plugged-in. When I look inside, I see a small light
that is lit.
The computer is resting on 2 bricks. The computer seems to be working OK
although the video intermittantly goes "black" briefly. The screen blanking
briefly only occurs when I use a particular video card. When I use the other
video card, the screen never blanks. Should I be concerned about the shocks I
get?
Click to expand...

I had a Radius Monitor, Circa 1996 (which is still beautiful), which
would zap me via the VGA cable. It wasn't a static spark, those are
transient, it was an actual current (never measured, but it was
actually painful). Yes, it really did have a 5-BNC to VGA tail.
 
The person suggesting the cause as defective wiring is most likely correct.
Many electronic devices utilize a "Line Filter" that consists of at least a
capacitor network, and often is even more complex. If the ground return is
defective, a fairly high voltage may be present on the chassis. If things
are plugged into the PC (USB, VGA, etc) and connected to something other
than the same wall recepticle, all sorts of interesting (and possibly
expensive) problems can occur.

Fortunately, the chassis to ground current is "usually" current limited to
something less than lethal.

Another interesting tidbit -- house wiring using aluminum ground return wire
and copper for the high and low side of the line commonly has the problem
you mention. The aluminum can develop high resistance connections at the
screw terminals on the wall recepticles, and even at the fuse/breaker panel
ground buss screw terminal.

If you live in a home that uses aluminum wiring for larger load items such
as A/C, hot water heaters, furnace, etc., The connections should be checked
periodically. Older homes built in the 1960s into the early 70s require
special care, and it is a very good idea to clean the aluminum wire and coat
with a compound such as "NoOx" prior to retightening the connections. (POWER
OFF Obviously)

I've had the aluminum ground return wires just fall off the wall recepticle
screw connectors when the wall recepticle is in the process of replacement
due to old age, wear, or the lack of the third ground pin.
 
b11_ said:
When I touch the computer case, I get a small shock even though the
computer
is turned off but still plugged-in. When I look inside, I see a small
light
that is lit.
The computer is resting on 2 bricks. The computer seems to be working OK
although the video intermittantly goes "black" briefly. The screen
blanking
briefly only occurs when I use a particular video card. When I use the
other
video card, the screen never blanks. Should I be concerned about the
shocks I
get?
Click to expand...
Assuming the computer power cord has 3 pins...
Make sure it is plugged in to a wall outlet with 3 holes, and any extension
cords or power strips used also use 3 holes and 3 pins.
Buy an outlet tester (about $5, available at WalMart) and plug it into the
outlet.
If the outlet tester gives any errors, such as an open ground, find someone
who knows electrical wiring and have them rewire the outlet.
Otherwise, place a metal object near the computer. Touch the object, every
time, before touching the computer to ensure no static electricity.
If the problem still exists, there is a problem with the computer and I
suggest you replace it or take it to a PC repair shop.
 
I forgot to mention that the computer is plugged into a UPS. I get a shock
even though the compter is off and the UPS is off. Doesn't that seem strange?
______________________________________________________
 
b11_ said:
I forgot to mention that the computer is plugged into a UPS. I get a shock
even though the computer is off and the UPS is off. Doesn't that seem strange?
Click to expand...

When I unplug the computer from the UPS and then touch the case. There
is no shock.

There is no rug in the room.
 
b11 said:
When I unplug the computer from the UPS and then touch the case. There
is no shock.

There is no rug in the room.
Click to expand...

If you are being shocked by the computer when it's connected to ANY AC
power source, you have a bad Power Supply in the computer and/or
possibly a bad ground in your AC outlets at the wall/circuit for your
home.

What brand UPS are you using? Does it have a building wiring fault
light?

If you bypass the UPS and connect the PC to the A/C outlet, are you
still getting shocked? (I would goess so).
 
When I unplug the computer from the UPS and then touch the case. There
is no shock.

There is no rug in the room.
Click to expand...

Then you are certainly dealing with a ground leak and a ground circut
that doesn't work.

As has been said, get an outlet tester. Test the wall outlet alone.
If that's ok, plug the UPS into the outlet and test the UPS. If both
of these are ok you've got a bad power wire or a bad power supply.

Don't just put up with this. So long as things are dry this is merely
annoying. Add some water (say, coming in from the rain) and the
resistance drops--and it could change from annoying to deadly.
 
Loren said:
Then you are certainly dealing with a ground leak and a ground circut
that doesn't work.

As has been said, get an outlet tester. Test the wall outlet alone.
If that's ok, plug the UPS into the outlet and test the UPS. If both
of these are ok you've got a bad power wire or a bad power supply.

Don't just put up with this. So long as things are dry this is merely
annoying. Add some water (say, coming in from the rain) and the
resistance drops--and it could change from annoying to deadly.
Click to expand...

I'd add coffee and sodas to the hazard chart.
 
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