Shock when unplugging guitar cable!

[Matt D]

Tonight I fired up my 18 Watt trem amp after not playing it for a week or so. It seems like since the last time I played it the amp has developed a significant buzz, a tendency to amplify RF noise and the weirdest of all:

When removing the guitar cable from the jack I get a brief but significant shock as I remove the cable. There is no shock when the cable is plugged all the way into the Cliff jack. It occurs just between when the tip is removed from where it is locked into it's contact and when the cable is out of the amp. Anyone have that happen before?

I'll get some pics up tomorrow when I have some better light.

Thanks guys

[Cliff Schecht]

Sounds like you need a DC blocking cap on the input of your amplifier (i.e. first thing off of the jack before any resistors or tube grids).

[Matt D]

Off the ground of the jack or the tip? When nothing is connected to the tip connection of the jack, and the tip of the cable is connected to the ground of the jack, the chassis is becoming live. Sorry if I haven't done the best job of explaining this.

[azatplayer]

Hey Matt, was this a build? recent? Or somethin you bought?

[selloutrr]

Lots of reasons this could have happened.

Were you using a Variac without an isolation transformer?
2 prong (no ground) power cord or adaptor plug?
Does your amp have a Death cap connected to the ground?


What modifications are done to your amplifier?

[Matt D]

Thanks guys,
This morning I switched to a different outlet and the problem went away so I guess I'm going to chalk it up to the lame wiring in my apartment.

[selloutrr]

might be a good idea to get an outlet checker and test your outlet. if it's not properly wired. it could lead to an electrical wire or personal harm.

Probably a DIY cut cost wiring mistake. ground might not be getting a solid connection. often times paint is covering the copper bus wire from sloppy work.

http://www.frontiernet.net/~tesla/html/ ... check.html