Reverb Tank Help

[Vez]

Greetings everyone I'm new here.
I have a 1966 Magnatone MP5 that has a broken reverb tank. The tank is made by Gibbs Mfg and my ohmmeter reads open circuit on one of the transducers in the tank. I thought perhaps I could unwrap a few windings and resolder them.
Has anyone ever repaired one or do I have a new door stop?
From what I've read the Gibbs is a quality tank and I'd like to repair it or have it repaired if possible.
Does anyone know anybody that fixes these things?
Should I just replace the tank?
Thanks.

[The Dude]

Welcome to the place!

Sometimes the wires come undone from the RCA connectors to the transducers. Have you verified that it's the transducer winding and not the wires leading to the transducer? If it is the transducer itself, I would just replace the tank.

[nevetslab]

The majority of the reverb tanks I repair are Accutronics and the current Belton-Accutronics tanks. Only twice have I been successful in backing off the insulation wrapping one of the transformers. The wire is, of course, extremely fine AWG, and you run the risk of breaking the wire in the process of removing the varnish coating. If you have the patience and the touch, then I encourage you. If you make your own flys for fly-fishing, then you're ahead in the game, apart from the angle of attack to get at the coil. The assembly is, after all, only held at the four corners with the suspension springs to the outer frame. I managed to repair the two without removing them from the outside chassis, but, I haven't been so inclined to do it of late, as my eyes are getting worse.

The last Gibbs tank I worked with came out of a Sunn 1200S.



It's much easier to just replace the entire tank. What usually fails are the tine connecting wires from the RCA connectors. For years, Accutronics was using IDC connectors that pushed onto a pair of pins, where those tiny transformer wires were wrapped around it and soldered into place. Usually they would break off of the IDC connector, and it was easier to scrap the IDC connector, tin the terminals and tack-solder the leads to those. Or, the same when they break away from the RCA connectors.

This tank shown was found to be very dark and murky sounding, and I ended up using an Accutronics 4AB3C1A tank to replace it, which sounded far more open and responsive.

[Vez]

Thanks Dude! Yeah I'm sure it's not the wires on the RCA Jacks. I've checked ohms up to the inductors.

[Mick Bailey]

I fix reverb trays all the time. You have to be creative in removing the transducer and If it's a tubular rivet I drill off the head(s) and persuade the coil to come free. Sometimes the laminations need to be slid along the springs and the centre lams bent outward slightly to remove the coil. Depends on the particular type. If you're really lucky you can do a repair in-situ if the coil is broken on the outside wraps. Reverb trays are not critical at all and will stand a few layers coming off without detriment.

When reinstalling the coil I use a 1/16" brass screw and nut to pass through the remains of the tubular rivet (10BA size here in the UK). Sometimes a bigger screw needs to be used. A spot of superglue on the nut prevents it from working loose.

If the coil needs rewinding I don't even set up my pickup winder. Just some masking tape wrapped around a small drill bit in the chuck of a variable-speed drill and mount the bobbin on that. Tape a few inches of wire on the chuck and then hold the drill flat on the bench and wind on a full bobbin. The output coils usually fail more often than the input side and in a regular tube recovery stage work out at about 220 Ohms. I use 43G wire, but anything close is OK.

I have 100% success rate in rebuilding trays. A little patience and thought and all of them can be fixed.

Just make sure you;re certain it's the coil before doing anything invasive. Connectors, solder connections and leads are the most common cause of failure.