Dungeon Master Forum

Hullo... I'm afraid I've got another computer problem : since yesterday, I've been receiving little electric discharges after turning on my computer : the switch is on the back and when I touch the metal, I get shots of electricity in my fingers. I hadn't noticed this before and I'm getting pretty scared of burning down my brand new hardware... I'm using a lightning proof adaptor, but the power plug doesn't have a ground connection. This might be an explanation, but then why didn't this happen since day one ?
Sorry about this dumb question, it's pretty difficult to find something so specific on Google. Thanks for any help.

Switch in the back? Do you not have a power switch in the front?

Friend had is motherboard arc a bolt of energy to the side of his case.. fried everything. He had a ground.. and still to this day can't understand why it happened. But certainly seems like a grounding problem.

not sure what to say.. you may want to look at ways of grounding it. a wire from the case to the floor?

moo

Personally I would ge tit looked at by someone, either the seller, or a hardware store if it is out of warranty!

Scary stuff... Yes I think I'll have it looked at. Even though it hasn't happened today, somehow.

ADDF : I have a switch on the back panel (to cut off the PC from the mains, even though I have another switch on my adaptor), and one on the front as well to really power up the computer. The problem being on the back panel : as soon as the PC gets connected to the mains, the metallic back panel gets charged with eletricity (well it did for 2 days).

Is it a 'static' discharge or a constant 'buzz' of current?

It seems to be a constant buzz... Keeps stinging until I take my hands off.

Florent wrote:(to cut off the PC from the mains, even though I have another switch on my adaptor)

Isn't the word "adaptator"?

I also agree that you should definitely let someone look at it, and if you can, use your machine as little as possible until this is fixed. Apart from that, I can't really give you advice, though.

I think we can safely say that something is intermitently shorting against the case. Luckily it isn't the 130v power supply or you would not be emailing us to tell the story...

The last time I had this phenomenon was with hifi equipment when the ground from the outside of a phono cable was touching the metal case. Maybe you have some dodgy connection somewhere, ie a USB cable which is shorting to the case?

Paul, I think you may have pinned the exact problem ! I have a USB cable connected to the back of the case, and running along the side of it. The connector was probably touching the case (even though the case itself was not delivering any buzzes, just the metallic back panel). That USB cable wasn't set up like that before, which explains why this never happened, and I used it this morning and left it in a different position, so this must be why I'm not having any more buzzes. I had already had a few tiny electric shocks from the cable's connector (of the "mini" kind, not the regular USB rectangular jack - those don't buzz so easily).

Thanks very much Paul !!!

Trantor : You had me wondering for a second !

Thank you all, hopefully this case is closed. I'm not writing from the buzzy computer, so I'll have to check later, but this definitely makes sense.

Ooooh, I reckon thats 50 quid plus tax you owe me lol!

Not that I'm trying to dodge paying your expert fees Paul, but I'm sorry to report that it's still doing it. Sounded right, made sense, but doesn't work, I'm still getting some current in my fingers. Unplugged the USB cable, even unplugged my printer and speakers, still not good.

strange. Have you tried not touching the metal?

Tsssss...

It is good advice, you must admit : ) I guess it's hardware shop after all...

Yup...

You must have guessed that was me from the "small word + suspension marks + smiley" combination. [Insert appropriate smiley here]

Florent wrote:Tsssss...

What's this supposed to mean?

I'd Say thats a bad thing

Sorry for dragging up old post, I just got back to reading these forums again

In case it's still doing, or someone else experiences the same... If the computer is not in a grounded outlet there will be half of the mains voltage between the case and ground. It's nothing dangerous if the Power Suppy Unit is good, as it's only a few milliamps, but you will know it if you manage to zap it on your fingers. (It's more than enough to zap electronics however, if you attach devices that are in different potential)

For the technical side, what causes the current potential is the filter capacitors on the PSU. All real capacitors are not ideal devices, so they have some leak current through them. Often times, when a capacitor is failing, the leak current increases.

It is possible, that you have one bad capacitor in the PSU and you feel the increased leak current. You need to have the PSU checked.

In the worst case scenario, you can end up with a short and the case side of the PSU will end up in mains potential. This is very dangerous, however it's very very rare, as modern PSUs are protected and should trip when it happens. However, this is another reason why all PCs should be grounded.[/i]

Thanks Toni for your in-depth explanation. I don't know if this is a typical French problem or if I'm just unlucky with the places I live in, but I never had grounded outlets ! Well, there's one in my flat, but it's too far away, in the kitchen. I remember another place I lived were the outlets had a ground plug, but they weren't actually connected to the ground !!! Oh well...

florent, it seems that we live in similar flats ! i have only two grounded outlets here, in the kitchen and in the bathroom.
i suggest you to buy a stabilizer/inverter (that's what google says for "onduleur"), and maybe a new power supply.
i didn't experiment electric discharges but i had many weird problems on my machine for one year (strange reboots, hangs and even hardrives stopped spinning !). so, i bought a brand new power supply (Tagan 420W Black Edition, a bit expensive but i don't regret it) and all my problems disappeared.

Méfie-toi des boitiers et alims pas chers !

Merci Linflas for the tips !
By the way the discharges are "gone" at the moment, I believe there might be a connection with the impressive heat in Paris at that time.
I might be moving in a few months, let's hope this time I have a grounded outlet near the computer !

Florent wrote:Thanks Toni for your in-depth explanation. I don't know if this is a typical French problem or if I'm just unlucky with the places I live in, but I never had grounded outlets !

That tends to be quite typical to any older building, atleast in Europe. Even 20 years ago there simply wasn't that many electronics devices that should be grounded around (or any kind of around really). New houses in Finland are starting to be all grounded, but this has only been the trend few years here.

Truth be told, I have never had my PCs grounded either because of lack of grounded outlets (and as a consequence I have zapped 1 video card TV out...). But this summer I finally fixed it and had the outlets in my apartment converted to grounded...