Repair reverb unit spring attachment

[nashvillebill]

Well I did it again, like a dumbazz I paid too much for an amp in need of far too much work.

Amp this time is a '67 Ampeg Reverberocket 2 (GS12R). Needs cap job, new handle, new isolation mounts, oh and the footswitch needs work. But at least the Jensen C12N seems OK... once I repair the speaker wire terminal which is broken (the tinsel is fine and the speaker didn't have any voice coil rub when I hooked it up to the sig gen).

...and then I found the reverb unit needs repair. One of the spring pairs was not attached and I see that while both ends of the springs are fine, the attachment point--a tiny little hook-like gizmo--is broken off. Looks like this is soldered inside a tiny brass tube.

I coulda swore a few years back I saw a guide to rebuilding reverb units, anybody know how this can be fixed?

Thanks!

[g1]

It can be done, but it's quite tricky and is never quite the same. The "hook-like gizmo" is actually a ferrite core, with the hook at one end of the core and a fine wire at the other end. The fine wire is soldered into the brass tube. Have a look at the good side and you should be able to see the core in the tube.
So for starters, you will need a donor unit you can steal a core from. I used to save them from bad reverb tanks along with springs etc. To remove it from the donor unit you have to heat up the solder at the back end of the tube and pull on the hook with a tweezer or something. But the brass tube is usually mounted in a plastic block which melts easily. So you want to put a clip or something to act as a heatsink on the brass tube near the plastic block. And try to be quick so the plastic doesn't melt.
Now on your unit you want to fix, you must remove the fine wire from the brass tube. Clean the solder off the back of the tube and you should be able to get on the old wire to pull it out.
Inside the brass tube there is also usually some foam or damping material. You will have to remove it or ream a hole through it in order to get the new core wire through the tube. Make sure the core is the proper distance into the tube before you solder the wire in place (compare with the good side).
The damping material change and the change in the core position are why it will never be quite the same.
Once you get the spring back in the new hook, apply a bit of nail polish if the other springs have it.
The key is to not let the brass tube melt the plastic block, good luck.

[nashvillebill]

Ouch. Looks like a new tank would be more cost effective.

Thanks!

[g1]

Yup, if it's not a vintage tank that you can't get a replacement for, it's not worth it. When we used to do this, tanks were very expensive. They sold transducer blocks to repair them and the blocks cost more than some whole modern tanks cost today.
But now some folks want their vintage tank to keep their vintage amp stock. And some won't settle for a non-us made tank. So it's not a completely worthless bit of trivia .

[52 Bill]

But now some folks want their vintage tank to keep their vintage amp stock. And some won't settle for a non-us made tank. So it's not a completely worthless bit of trivia .

The former Accutronics people apparently still have a stock of parts for the old US made tanks. They are offering a rebuild service for Accutronics tanks on eBay.

I used to save all of the dead tanks for parts, but after a while, all of the same parts were used up.