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Please help me with this scary pc problem

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sram

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Hello guys. It has been some since the last time I posted here. I have a weird problem, so let's hear it.

On one of my machines, I was using a metallic case. If I touch the case, I'll feel electrical current flowing into me. The PC is working perfectly with no problems. You can feel the shock! It happens even if the PC is shut down.

Here is what I did:

I checked all connections, wires....etc to make sure there is no stupid short somewhere, but everything seemed okay. I tried more than one power supply but it didn't help either. I changed the power extender also, it didn't help. Thinking that there is something wrong with the pc, I plugged my another machine. The same thing happened to it!!! This happened although the other machine wasn't experiencing this before. The only common thing now is the wall outlet. Could there be something wrong with wall outlet that will cause this???

What do you suggest I do?
 
Check your monitor. Unplug your monitor and see if the problem is still there.
I have had it that when i unplug my monitor it gives me shock.
 
You don't have your location filled in - and as with many questions, it's dependent where you are.

But any civilised country will have earthed sockets, and PC's are class I devices and the casings are earthed.

Sounds like the earth is missing from your socket?.

Another (less likely) option is that the casing is earthed, and YOU are statically charged - so get a 'tingle' as you discharge to earth via the casing..
 
See if you can borrow or buy a socket tester, they arent expensive nowadays and make sure as Nigel says that your socket is earthed.
You can also use a multimeter to make sure theres continuity from the mains connector to the case of the pc.
If your not confident with any of this then get someone to check it over just in xcase something is well amiss.
 
I once experienced this on a device where earth and neutral had been swapped. The problem is in the outlet. Check it if you know what you're doing or get it checked by someone qualified.

Actually, you can also get this effect if the property is on three phase and the phases are widely out of balance. Same cure as above.

Mike.
 
Historically, particularly when installing washing machines, it's important that the socket has a decent earth. It used to be standard practice to carry a test lamp, fitted with a 100W bulb, with the plug wired between Live and Earth. Before you connected the new washing machine you plugged the lamp in, and the bulb had to light brightly, this showed the earth was reasonably good.

Obviously this has long since ceased to work, as it would instantly trip a modern ELCB.
 
As above, my money is on a bad earth either at the socket or on your socket to PC lead.

I've had this happen before on both computers and large industrial machines (which the electrician forgot to earth !)
 
We have blown many laptops due to this issue. On a double insulated system which a laptop is, the 0V on the RS232/USB 0v sits around 160V above earth.
 
We have blown many laptops due to this issue. On a double insulated system which a laptop is, the 0V on the RS232/USB 0v sits around 160V above earth.

As with any double insulated item, but it's only very low current (and is done that way to prevent a high static charge building up). It would be rare to 'blow' the laptop, I would suspect there's something else causing it, but of course you shouldn't be connecting/disconnecting RS232 without powering down anyway.

But this has nothing to do with the OP's question.
 
Okay ........I'll check earthing and come back. Nigel, again and again you are a great help. How is your health?

Thanks to all.
 
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Indeed it was the earthing. Sorry, life distracted me from getting back to this thread to report back!!!. Thanks.
 
Excellent - always good when you find the problem and good job you found it before it did some damage :)
 
Off topic,

Hi Nigel,

Wow laser surgery! I am not brave enough for it but would love to get my vision better.

How did they do yours? Is it still a case of peeling back a layer of the eye to do it? That is what scares me mate.

Anyway well done mate for going for it. Wish I coud get rid of the varifocals! ;)

Al
 
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Try this problem on for size. Computers were failing. The problem: Due to a manufacturing defect in the duplex outlet, one ground would let go depending on the position of the other plug in the duplex outlet. The ground connections were purely pressure on the ground contact when the outlets were assembled. You could see the arcs in the dual ground contact when you took the outlet apart.

You had to use an outlet tester in one outlet and put a plug in the other and wiggle it. Nearly 430 outlets were potentially affected. Some were just replaced and others on an as needed basis. If something was plugged into an old outlet, it was checked first and replaced if defective. Replacing and/or testing 430 outlets wasn't an option, but it was recommended by me.
 
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