I've tried to turn on my old PC with my old LCD monitor, which is powered by a kettle cable directly from mains, no power supply brick). When trying to get it to work, I have noticed the following phenomena:
1) The VGA connector from the monitor produces electrical sparks against the PC case, even when the PC PSU is switched off (but both are connected to the same extender cord) - See video: https://youtu.be/6Jxlndc2ZUA
2) While bending down to look at the connector (with the VGA cable connected), and touching the PC case with my hand, my head accidentally touched one of the strings on my electric guitar and I felt an electric spark on my head (not very strong but noticeable). The guitar is connected to an external sound card, which in turn is connected via USB to my main PC, which is connected to a different power outlet.
At first I assumed it's some kind of grounding problem on my monitor. So I hooked up some random grounded electrical device I found in the house (the base of an electric kettle) to the same extension cord, and tried to brush the VGA cable against its metal casing while the other end is connected to the monitor. I couldn't see any sparks this time.
I have also tested this the other way - I have connected the VGA cable to my PC, and tried to see if it produced sparks when rubbing the other end against the electric kettle base casing, and nothing happened.
Since I am alive and the sparks don't look too big, I assume the VGA cable isn't really live with 220V but instead something else is going on.
Can anyone suggest an explanation to the above situation?
I have repeated the experiment using a different wall plug and extension cord, one that I have personally tested with a multi-meter and made sure that is wired correctly regarding live/neutral/gnd.
Turns out that one of the kettle cables I have been using is indeed missing a ground prong, and has a hole instead:
This is meant for sockets that have a ground prong (mine doesn't), so effectively, it wasn't grounded.
I have tested the following combinations:
1) ungrounded monitor, grounded pc (psu off) - VGA cable is arcing against PC casing 2) grounded monitor, ungrounded pc (psu off) - VGA cable is NOT arcing against PC casing.
In this case, I assume there is some kind of issue with the computer monitor. Getting a grounded power cable for it would merely hide the problem, and I should probably replace it.
Is there anything else I should look at before dismissing the issue, just to be safe?