T.O. Vox Reverb problem

[brutus]

It's pains me to say it.. but my beloved Vox Buckingham has a problem. The reverb is very weak it is still there just not loud in the mix. It is at about normally would be 3 but it is turned all the way to 10. I hope it is a easy fix because we all know these are a pain to work on. Any ideas on what could be the problem? Thanks guys...and gal. {it is a spring reverb]

[jtr654]

If all the connections are tight it might be a op amp or transistor that going bad. What year is your amp?

[Veenture]

Is the reverb tank tube driven? (check the tube). How many springs? (check if they're all still in place).
Just my immediate thought.

[jtr654]

Buckinghams were tranistor only amps from the Thomas organ era.

[MWaldorf]

Check to make sure the pan itself is ok. These can fail in a couple of places, the most common being the wire connected to the rca jacks, or the transducers. If the transducer (the red bobbin with the yellow tape around it) is loose, it doesn't transmit the full signal. You can increase the signal transfer by shimming the transducer with a toothpick so that it doesn't wobble.

If you find you need a replacement pan, just make sure you get the same type with the correct input and output impedence. The type should be printed on it, something like 4AB3C1B

[brutus]

Thanks for the imput everybody. I will take the unit out so I can see whats happening.
I don't really know what year it is, when I got the amp the owner said that he used it in a band in the early 70's.

[Mr. Bill]

First off 95% of all spring reverb problems are mechanical. Broken wires, broken transducers, broken spring mounts, etc. Always check the tank first for any problems. In your case, there could be a broken wire to the input coil. It usually happens at the RCA jack.

Historically, Thomas Organ used 2 drive circuits in the evolution of the Vox solid state amps. The earlier ones used a low impedance input tank, while the later ones used a simple single transistor driver circuit that required a higher input impedance transducer. What model Buckingham do you have? The model will be a number something like "V-1152", usually located on the ID tag on the back of the head.

If the reverb was working fine before this, then either there is a bad connection to or from the tank, a problem with the tank itself, like a broken spring, or a broken wire inside the amp, or a problem with the circuitry.

If you shake the head does the reverb springs sound loud through the speaker? If it does seem to make the same amount of noise as before, then the problem could be in the drive circuit. If it doesn't, then you could have a problem with the recovery circuit.

If you have the earlier version of the head, you can swap the tank with one from a Fender reverb amp, as they share the same specs. If you have a later version, then the Fender swap will not work.

[jtr654]

If it's the tank Ampware.com is where to look for a replacement.

[Mr. Bill]

I haven't used Ampwares in a while.

Antique Electronics was recently selling a bunch of tanks for less than $20.

One of the main problems with replacing a TO Vox tank, is the color. Because of the position that they are mounted in the head, the original ones were finished in black. For repairs where looks are important, I'd swap out the internal spring tray to keep the original look.

[brutus]

V11-21 is the model number. I think it is a 72? did they make them in 72 i don't know. There is a 72 prefix in the serial number. I had the caps and ect. replaced about
5 years ago, and the reverb has never been the same, althought the amp sounds great. This weekend i will take out the pan and hope for a easy fix thanks for the great info guys.