Amp Grounding Problem

[maxabillion]

Alright, dumb question here , but I have nowhere else to turn. My amp is not properly grounded. I bought a new plug for it about a month or two ago (it has the third prong ground on it) and as far as I can tell there are no other issues with my rig. But every time I am singing into my SM58 its shocks my lips if I accidentally touch it. I try to sing far away, but I would like the grounding not to be an issue. Any thoughts.

Rig:
Gibson SG - Boss Multi effects pedal - peavey windsor head - avatar cab. Pretty straight forward, all new (or new-ish) cable. This is so far only an issue in my room, but if I remember correctly it has shocked me in rehearsal studios before as well.

 

[bouldersoundguy]

Get the amp looked at by a professional electronics tech with tube expertise. Your life may depend on it.

 

[mjbphotos]

If you 'bought a new 3 prong plug', did it have a 2-prong one before, and if so what exactly did you hook up to the ground prong? The problem you describe was more common in the 'old days' when amps came with an un-keyed 2-prong power plug and there was a polarity switch on the back of the amp.

 

[ranjam]

This is the only way to do it; 2to3prongconversion

 

[Victory Pete]

Get one of these and check your outlets, there are lights on it that will tell you if the outlet is properly wired or not. Amazon.com: Triplett 9610 Plug-Bug 2 GFCI Receptacle Tester for 110-125 VAC: Industrial & Scientific It also has a button to test GFCI outlets which are good to have in a studio to help prevent shocks. Have an Amp Tech take a look at your gear as well, it might be your PA that has a problem.
VP

 

[maxabillion]

It had a 3-prong before but the grounding prong (the round prong that goes in the lower hole?) was loose so I bought a new one. I have a relatively new amp, so I don't think its an age issue, but I will have a tech check it out. Thanks!

 

[Dogbreath]

But you said it shocked you when your lips touched the mic.

"This is so far only an issue in my room, but if I remember correctly it has shocked me in rehearsal studios before as well."

Same mic?

 

[Victory Pete]

You could get a digital meter and take a reading between the SM58 and your guitar amp and see if voltage is present.
You would have to understand how to use it, you could be getting AC or DC voltages.

http://www.homedepot.com/buy/electr...rs/klein-tools-digital-multimeter-126773.html

VP

 

[Victory Pete]

VP... Have you got one of these Amazon.com: Fluke 1AC-A1-II Volt-Alert AC Non-Contact Voltage Tester: Home Improvement . Bought one to check dead lights on Christmas light strings and live circuits and it works pretty slick. Not sure it would detect voltage on a guitar amp or mic though.

Yes, I have those, I would not depend on it though, I dont think they work with DC and they are tempermental some times. I have ruined pliers before cutting a wire that was live even though the probe said it was dead.

VP

I didnt see that last post, interesting, that might be AC then, I am curious to what the voltage is.