Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: lkrasner on March 07, 2015, 08:37:40 am

Title: Blackface Pro Reverb Shorting Input Jacks
Post by: lkrasner on March 07, 2015, 08:37:40 am

I'm fixing up a 1967 Fender Pro Reverb. Currently, the inputs always stay hot, even with nothing plugged in. This causes some hum if the knobs are turned up on the channel I am not playing through. It has the shorting type jacks, but clearly they are not doing the usual job of shorting the signal to ground like I usual do on my new builds, and the wiring is somewhat confusing; I can't quite get my head around it.

Anyone know how to mod these jacks to short the signal to ground when unplugged?

Here's the layout and schematic, just so you don't have to go look it up ;)

http://vintagefenderamprepair.com/wp-content/uploads/2011/04/Pro-Reverb-AA165-layout.pdf (http://vintagefenderamprepair.com/wp-content/uploads/2011/04/Pro-Reverb-AA165-layout.pdf)
http://vintagefenderamprepair.com/wp-content/uploads/2011/04/Pro-Reverb-AA165-schematic.pdf (http://vintagefenderamprepair.com/wp-content/uploads/2011/04/Pro-Reverb-AA165-schematic.pdf)

Title: Re: Blackface Pro Reverb Shorting Input Jacks
Post by: sluckey on March 07, 2015, 09:08:43 am

Just wire the jacks IAW the schematic in your link and they will work as expected. Here's a pic that may help...

     http://el34world.com/Hoffman/files/CommonHookups.pdf (http://el34world.com/Hoffman/files/CommonHookups.pdf)