Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: musicfixerupper on April 01, 2011, 12:56:55 pm

Title: Reverb problem
Post by: musicfixerupper on April 01, 2011, 12:56:55 pm

hey there, i am working on a new vibroverb build. I am getting no reverb. Voltage on the plates of the 12AT7 reverb tube are 450 but at the cathode its 0V. I also just noticed the the filaments are not lighting up on that tube. All other tubes are lighting up. tried different tubes in place of the 12AT7 and still no filament. 3V is present at pin 9 and 4&5 at both ends so they cant't be broken.  Maybe its an oscillation?

Title: Re: Reverb problem
Post by: LooseChange on April 01, 2011, 01:43:34 pm

If the tubes not lit, it's not going to work. Check the connections carefully... No way is it oscillations.

Title: Re: Reverb problem
Post by: Tone Junkie on April 01, 2011, 02:58:24 pm

I will say this I just did a build all voltages checked out from the top side but the tube would not light up was a bad solder joint on pin 4 when i touched it had the proper voltage but it wasnt making it to the tube I dont know why, I wiggled things and it came apart then resoldered it and it worked perfect.
Thanks Bill

Title: Re: Reverb problem
Post by: tubeswell on April 02, 2011, 01:18:16 am

You might have a loose socket pin? (Try re-tensioning the pins)