Shocking 5E3 clone problem!

[Don]

I have a great sounding 5E3 clone that I've been playing for a couple of years.

Recently I got zapped pretty hard while playing my guitar through it.

It turns out that the ground failed in my cheap power strip. The ground rail fell off of it's heat staked posts. It has been dismantled and thrown away.

On the bench, I simulated the ground failure and found 38vac between the amp's ground and ground 167vac with the amp turned on.

This happens even with the rectifier, power and preamp tubes removed.

The amp sounds fine and all other voltages are fine whether the ground is lifted or not.

I assume that it's not normal. Any idea what would cause it?


BTW, I do not play my amps with the ground lifted!

[Alex R]

Voltages on an ungrounded chassis will rise and drift around, though those do sound kind of high. But as V=IR, and you are applying a massively high R by disconnecting the ground altogether, the implications for actual current flow don't have to amount to anything much. However, it did run some current to ground through you...

To find out if it is wanting to leak significant current to ground from the chassis, you could clip a resistor - like 100 ohms or something - between the chassis and ground and see if any voltage is dropped across it. That would imply a current flow to ground, which would show a dangerous fault. That's the current flow that would trip what we in the UK call an earth leakage circuit-breaker if you had one.