Electrifyed Computer Case/tower

[paulfr]

I really would like to stay out of this.

There is so much mythology and misinformation here it would take me an hour to explain the various points. And that will not solve BoomBoom's problem.

But I do feel a community responsibility to repeat ......

If you feel a shock when touching your CPU case (or anything other than

a rug induced static charge) there is enough voltage there to KILL YOU.

It is not right and you should get it corrected ASAP.

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BoomBoom

My first recommendation is the same; get a professional to look at it and make

the shock go away.

Also, check to see if the PSU does actually have an isolation transformer in it.

I keep forgetting TIT. If it does NOT, replace it with one that does have one. If it does not, it will be very light, like a volleyball. If it does, the transformer is very heavy and you will feel it.

Also, try to keep all CPU related devices (monitor, printer, camera, etc) connected to one power strip. If you have two power strips, make sure they both connect to the same wall socket.

Disconnect any other devices like fans and AC units from these power strips.

Feel free to PM me with any other questions.

[lopburi3]

I really would like to stay out of this.

There is so much mythology and misinformation here it would take me an hour to explain the various points. And that will not solve BoomBoom's problem.

But I do feel a community responsibility to repeat ......

If you feel a shock when touching your CPU case (or anything other than

a rug induced static charge) there is enough voltage there to KILL YOU.

It is not right and you should get it corrected ASAP.

----------------------------------

BoomBoom

My first recommendation is the same; get a professional to look at it and make

the shock go away.

Also, check to see if the PSU does actually have an isolation transformer in it.

I keep forgetting TIT. If it does NOT, replace it with one that does have one. If it does not, it will be very light, like a volleyball. If it does, the transformer is very heavy and you will feel it.

Also, try to keep all CPU related devices (monitor, printer, camera, etc) connected to one power strip. If you have two power strips, make sure they both connect to the same wall socket.

Disconnect any other devices like fans and AC units from these power strips.

Feel free to PM me with any other questions.

<{POST_SNAPBACK}>

Voltage kills?

Unfortunately most power strips sold at other than computer shops do not have a ground. They will have the three holes but the ground pin will not touch anything. A key to this, other than the cheap price, is usually they only put a two pin plug on them. Check closely and if in any doubt take out the screws (after unplugging) and check that the ground pins are attached to cord wire.

[jackr]

Bang a three-inch nail in the ground where the floor meets the wall and run a cable from the casing (eyelet crimp onto case fixing) to the nail (cut top off nail and slide over 10-amp chock block; terminal block). You'll know if you've gone deep enough when the LED light goes out on the voltage tester terminal srewdriver you've bought. When you move out, just lop it off at floor level and bang it further down with a hammer and punch. If no earthing in your digs, you'll have to do this for a washing machine as well due to the voltage induced by the drum motor. If not, you'll get a pisser every time you touch the drum or grab the wet clothes. Current has to go somewhere, can't go down the neutral!!

Hope this helps.

[Ice Treasure]

The cause is crappy grounding caused by crappy power supplies made in Thailand. End of story.

Fix it in a 12th floor apartment, get a single piece of copper, and take a power point off the wall.

Wrap the wire around one of the screws holding the power point to the wall and screw the power point back on, securing the screw to the concrete wall.

Unplug the PC from the wall and unscrew one of the screws holding the power supply to the computer, (not a case screw). A tab is a good idea but they are hard to find so just use the wire with a washer on top.

Screw the wire down under the power supply screw. Connect to the wall socket again with power. Check voltage between earth and the case using you. (Does it still tingle?)

You are fixing one piece of crappy thai work (the power supply) with another piece of crappy thai work (the concrete reinforcing).

Hope it helps. All this technical rubbish about power supplies etc makes me laugh. If your Thai bought computer does it and your foreign bought one doesn't, what does that tell you?

If this doesn't work, wear shoes when playing with the bloody thing or work on a mat.

[geronimo]

"You could also test this by sticking a light bulb in your mouth and then grabbing the computer and the nearest earth. "

I do hope you are kidding here. This may be the funniest most erroneous comment I have read on a chat board in more than a year.

This subject of grounding baffles most professional EE's that I know.

Get an electrician to make the shocking due to your case go away.

Or take it to Pantip Plaza or Fortune IT Plaza if you are in Bangkok.

<{POST_SNAPBACK}>

I agree with the others who say there cpu's are always "live" and it's nothing to do with a faulty power supply .... simply no earth in the electrical system. The copper pipe or fix to an a/c unit is the way to go!!!!

[Thetyim]

"The copper pipe or fix to an a/c unit is the way to go!!!!"

Ehhhh I hope you don't mean what this sounds like

[paulfr]

"The copper pipe or fix to an a/c unit is the way to go!!!!"

--------------------

This general idea of just connecting possible grounds is one of the

myths I was talking about.

Personal safety is one major objective of system grounding.

Fire safety is another.

This advice to just start connecting things to "grounds" (water pipe,

A/C unit, concrete rebar, etc.) is a very good way to start a fire.

Why ??

Because grounds from different sources/mains feeds can easily be

several volts apart. And they are what we call low impedance sources.

That means they can source/sink large amounts of current.

Connecting them causes current to flow between them. And the only

thing limiting this current is the impedance/resistance

of the wire which is very low ... like 10-100 milliohms depending on the

length of the wire. So very large currents can flow, melting insulation,

creating heat and then flames.

I hope you have/will read my previous posts in this thread

and consider them carefully.

[Ijustwannateach]

Paul, I think I understand and agree with what you're saying- and I have the same problem with my computer case (with everything else disconnected and the power plugged in). so let me see if I understand- I need to get a good EXTERNAL power supply [with the transformer thingy you're talking about], or is it the power supply INSIDE the casing that's the problem?

"Steven"

[paulfr]

Paul, I think I understand and agree with what you're saying- and I have the same problem with my computer case (with everything else disconnected and the power plugged in). so let me see if I understand- I need to get a good EXTERNAL power supply [with the transformer thingy you're talking about], or is it the power supply INSIDE the casing that's the problem?

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The Power Supply inside is the likely cause. Some component is leaking or there may just not be an isolation transformer. I don't know.

But since you get the shock from the case with everything else disconnected, you can do one of three things ..

1/ Replace your PSU with another more expensive brand name PSU.

2/ Disconnect all wires from your case to the motherboard or other components and let the case float. (float means it has no connection to the system, thus no voltage on it)

3/ Take it to Pantip Plaza or Fortune IT Plaza. Some have poohooed this suggestion, but I cannot believe techs who work on computers all day will allow themselves to be continually shocked. They probably know three ways to make the computer safe to touch and can do it in a few minutes while you wait.

Make sure you get the shock with the monitor/display disconnected so you don't have to take that with you in the car/taxi.