iMac gives electric shock
Since I bought my used iMac last summer, I've noticed such a unpleasant and painful issue with it. It constantly gives me small electric shocks.
The first time it happened, I was trying to plug usb behind it, I though it was just static electricity, but as it was happening more and more, I find out that I was wrong.
I get shocked every time my skin touch the aluminum body. The more lightly I touch it, the more painful it is. It's like stings. It's even more painful when the skin is thin, like with my wrists.
What tells me it's not static electricity is that, If I keep my wrist on the corner of the screen, it doesn't stop, it's constant. It also happens with my wired aluminum keyboard.
It is not unbearable, but so unpleasant.
My house is correctly grounded, I've checked it and tried other plugs, same problem. I even tried at my parent's. So I think the problem comes from the iMac itself. The AC adapter doesn't have any problem too.
I've tried to ask Apple, the guy told me to turn the iMac off, unplug it, press the power button for 10 sec, and turn it on to see if it has changed : result no.
Actually it doesn't happen the first 1-2 minutes after I turn it on.
Does this already happen to you ? What could it be and what could I check/do inside to verify the correct grounding ? I'll tear it down at the end of the month to upgrade CPU so it would be nice to correct this at the same time