speaker output jacks - newbie DIY question

[silvertone1464]

Hi all.

Im in the process of fixing up my old Silvertone 1464, an old solid-state head'n'cab piggyback from about '67 or so, and ive hit a bit of a snag.

the last item on my list was to change the dodgy, cracked, hard-wired speaker cable out for a standard 1/4"-to-1/4" jack setup.

problem is, the signal from the 1/4" jack (when the amp is turned on) is energizing the amp chassis!

when the jack is hanging free and isnt grounded to the amp, it works just fine; but the second it touches the amp's metal case, the signal drops and the case is carrying current. shocked me real good, too. its a wonder it didnt short out before i could unplug it.

do i have the speaker wires from the circuitboard on backwards? does it matter? is there such a thing as an "insulated" 1/4 jack?!

im a clueless beginner.

HELP ME!!!

thanx!

[52 Bill]

when the jack is hanging free and isnt grounded to the amp, it works just fine; but the second it touches the amp's metal case, the signal drops and the case is carrying current. shocked me real good, too. its a wonder it didnt short out before i could unplug it.

do i have the speaker wires from the circuitboard on backwards? does it matter? is there such a thing as an "insulated" 1/4 jack?!

I think I had one of these way back when...

Speaker outputs are "polarized", if you will, one terminal is considered hot and the other ground. You should check out the schematic for your amp, and be sure thet you have the correct wire going to the tip terminal of the jack.

You should also be aware of the fact that some amps do not have an actual ground connection and will need to have the jack isolated from the chassis to work correctly. This can be done via insulating washers or plastic bodied jacks.

[Enzo]

Yes, I'd say you have the wires reversed.

But Bill's closing statement sums it up for me. Just use a plastic jack. Get one of those "Cliff" style jacks - we used to call them "Marshall jacks" around here - the ones with the big black plastic nut.

[silvertone1464]

thanks guys! that helps me alot!