Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: six el six on May 03, 2012, 02:50:33 pm

Title: 5B3 Fender Deluxe arcing at OT primary leads
Post by: six el six on May 03, 2012, 02:50:33 pm

I have a 5B3 that is arcing where the OT leads go through the chassis.

This is, of course, a real 60 year old 5B3 and the cloth wire is brittle, dusty, and almost colorless at this point.

I am guessing that the insulation is no longer insulating and the B+ is simply arcing where it needs to. The visible arcing occurs on strong notes and can be visibly observed around the knot tied in the OT primary leads right before they exit the chassis to go to the OT.

There are four leads going through the hole in the chassis. Both sides of the primary, center, and the extra is a ground.

Has anyone dealt with this before, how did you fix it,  and what possible solutions could be implemented?

Thanks,
six el six

Title: Re: 5B3 Fender Deluxe arcing at OT primary leads
Post by: sluckey on May 03, 2012, 03:53:51 pm

Disconnect the wires. Untie the knot. Pull the OT. Put a couple inches heat shrink on each wire so to help insulate as they pass thru the chassis. If there is a rubber grommet, replace it. If no grommet, install one. Reinstall the OT and you should be OK.

Title: Re: 5B3 Fender Deluxe arcing at OT primary leads
Post by: six el six on May 08, 2012, 11:36:13 am

After untangling the knot in the leads and inspecting them, sure enough, there were several exposed areas of wire from deteriorated cloth.

The heat shrink worked fine i.e. no more arcing.

Thanks Sluckey.