6FB2D Reverb Tank Issue

[Billy Penn]

I have a cool old Kustom V Lead with dead reverb. All circuitry works and I think the issue is a bad tank. Tank # is 6FB2D and has 180 ohms in and 180 ohms out. Does anyone know of a suitable sub? Thanks in advance!

[g1]

Those 180 ohm readings are good for an FB type tank. Are the springs intact?
As far as I know, that is a very small tank. Depending on how much room you have available, any other FB tank will probably work, you may have to alter the tank's grounding scheme.
But I would suggest you verify the tank is definitely bad before looking for a replacement.

[Billy Penn]

Thanks for the reply g1! Well....the drive and recovery op amps work fine. All continuity in the circuit is also good. Rub on the springs and you can hear a faint sound. But no reverb effect. One spring was loose and I had to solder in a new loop I took from another tank that threads through and holds the spring....hard to explain. Transducers both read 180 ohms and that matches the specs on the schematic. I'll check out the 8FB3C1B tank: https://www.amplifiedparts.com/products/P-RMOD-8FB3C1B
Although the impedance seems much higher than the 180 ohms original..

[g1]

Yes, if you had to replace a "core", chances are not so good of it working proper again. I've sometimes had success doing that but not always.
The impedance is not the same as the measured resistance. The linked article explains it, and what the other numbers mean. It should help you determine if the 8FB3C1B is the best option. The Mod tanks have adjustable ground scheme, so you don't have to worry about that part.
https://www.amplifiedparts.com/sites...d_compared.pdf

[Billy Penn]

Wow...that's a great link! On paper then the 8FB3C1B looks like it will work. I can mount it in the cabinet...there's enough real estate for sure. I'm just puzzled why it does not work even if the transducers read 180 ohms as noted on the schematic. And like I said both drive and recovery op amps work. Maybe I'll just order one up and give it a shot...Thanks for your time!!

[salvarsan]

See Roy Mallory's Spring Reverb Info Page for design notes and calculations.

[52 Bill]

Rub on the springs and you can hear a faint sound. But no reverb effect.

Most reverb return circuits have a lot of gain, so you should be hearing more than a faint sound. Are you sure the tank is plugged in correctly?

My quick and dirty test for reverb tanks is to shake the tank and listen for the sound of the springs rattling. Then switch the two RCA plugs and shake again. That will quickly test the continuity of the two coils.