Shock!

[espresso]

So I had my Strat plugged into my Express 5:25, while my wrist was resting on the bridge and strings I went to turn on my Valco Supro and got a mild shock when I touched the "on" toggle. This only happened when I touch the bridge.

I'm thinking it's the guitar and not the amp. Any ideas?

Dan

 

[mikey383]

It's probably your home wiring. Poor electrical grounding will cause that. You completed a circuit by grounding yourself, therefor, the shock.


Home Depot sells these plug-in testers that will tell if your outlets are wired correctly. They're inexpensive too...around $10. I would suggest buying one and checking the outlet that your amp is plugged into.

 

[Moot]

How old is your Supro?

Old amps often had a live chassis. You don't want to complete a circuit with your body.

 

[MrMarkIII]

Does the Supro have a two-prong A/C power cable? That's it.
Those old amps with two-prong non-polarized plugs will shock you, no matter what the house wiring is. Sometimes it helps if you unplug it and turn the two-prong plug 180 degrees then re-plug.
Best to get a three-prong installed.

 

[mikey383]

I didn't catch the part about the other amp.


Definately, if it is a 2 prong cord, that's where the problem is. The chassis on those old amps aren't grounded properly, leaving a shock potential.

 

[espresso]

The Supro is a 1947 model and it does have a two pronged cord. I guess that's the culprit. Thanks for all your responses.

As an aside, the Express 5:25 in Blues, 5W mode with gain turned up passed 2:00 can get you a pretty good old school break-up.

 

[Don]

If the Supro is a player you should replace the power cord with a three prong grounded cord.

I just sold my '68 Princeton Reverb and the fact that I had installed a three prong grounded power cord didn't hurt it's value at all.

Even if all of you amps are grounded correctly you should still check you outlets with an outlet tester. You'd be surprised to see how many outlets are wired incorrectly!

 

[MrMarkIII]

+1 on the circuit tester. Had a lot of re-modeling work done on the house, and using one of those little yellow testers, found all kinds of weird wiring snafus. One is in my cable bag for gigs, especially outdoors.
When you have a three-prong cable installed, make sure they do it right. I had an Ampeg Jet I bought retro-fitted incorrectly, didn't think anything of it. Went to play an outdoor gig, and each time I took it off standby it tripped the GFI on the generator and, oops, no power. Took a good 30 minutes to figure it out, and only then because the bass player was a tech-head. Had to use one of those grey third-prong-defeating adapters to get through the gig very carefully, without touching the mike!

 

[wastoid]

Clearly the solution is to bring along a metal spike with a braid and clip attached to it to your gigs. Then you can clip it to your tuning pegs and drive the spike into the ground so there will be a path of lesser resistance.

 

[espresso]

I'll be restoring the Supro soon and a three pronged cord will be part of it. Thanks for all your replies and suggestions.