Electric shock on touching the cabinet

[janitha]

It is found that there is electric shock when I touch any metal part of the cabinet. Over the last several years I never had such an issue. What may be the reason and solution? The first thing I did on finding the issue was to check the mains earthing using a multimeter and it seems alright. AFAIK, SMPS is the only part where AC mains is present and hence the only possible culprit.

[monkey]

I too had this problem. My Corsair PSU was brand new and hence it was difficult to blame it. The culprit, surprisingly, was monitor cable. There was some internal problem with the monitor circuitry and the current, somehow, managed to travel through VGA cable to the back of the cabinet. There it touches metal parts of the MoBo backplate and from there to the whole cabinet body.

[pimpom]

Good to know you had the sense and the knowledge to check the mains earth with a multimeter.

Did you check the earthing between the mains socket and an actual earth like a water pipe, or did you check between your computer and earth?

If you checked only the earthing of your wall socket, then the fault may be in the earth path from the computer to the mains plug. It could be in the spike guard, UPS or the power cord.

With everything turned off and the mains plug disconnected from the wall socket, check for continuity of the earth line from the computer cabinet body to the earth pin of the mains plug. There may be a break in the earth line, or it could simply be that the earth pin of the power cord is not making proper contact where it's plugged in to the PSU.

[janitha]

Thanks to all of you for the quick replies and suggestions.

Initially I had tested the mains socket using a multimeter. The voltage between left and right (neutral and phase) was normal. (~ 220V) Between earth and phase, it was near to the mains voltage. (~ 217-218V) and between earth and neutral it was about 2-3V. Hence I assumed everything was alright with the mains. Yesterday called a local electrician and he checked it using a bulb between earth and phase and seeing it lit he said that earthing is alright and I may get the PC checked and if necessary, he will install separate earthing for the particular room but being in a rented house, I postponed the option. (I know these tests are not perfect but we do not have access to things like impedance testers!)

All the while, the the connection was from mains to a Belkin Spike guard and from it to an APC 650VA which supplied to the PC, monitor and modem while the laser printer was fed by the spike guard itself. Today made the connections to PC and monitor through the UPS, avoiding the spike guard and the problem disappeared. Then connected the spike guard to the mains and measured the voltages and it is seen that the phase and neutral are reversed, the right side terminal being neutral and left one phase. So my provisional diagnosis is that the Belkin spike guard was the culprit.

[acewin]

seems you may have got the solution. I always like pimpom's approach for solution to these HW issues .

[sudhanshu39]

I too had exact issue and solution too was exact. The culprit was Spike Buster. Replaced it.

[Cool Buddy]

My friend has the same problem. I always thought it was the cabinet's design (cheap iBall cabby). But now I see that there can be quite a few reasons. Will ask him to check the earthing etc.

[mathikutty]

check earthing