When The Lights Went Out: Repowering a Deluxe Reverb Reissue. Enter The Avalanche.

A reissue Deluxe Reverb arrived here with a complaint of "no sound. Smells bad." and a brief investigation lead to some rocket science and the beginnings of a conspiracy.

The rectifier tube was defective and the power tubes were very weak. Some more investigation revealed that the primaries on the power transformer were open and therefore a new transformer was called for.

I had a Deluxe Reverb power transformer on the shelf but the original ones have a smaller footprint than the reissue amplifiers, namely the 65 Deluxe Reverb and the 68 Custom Deluxe Reverb.

However.....however the footprint is the same as the original power transformer for a Vibrolux Reverb or a Tremolux. As it happened I had one, and comparing published data I soon realized that not only could I use it to replace the failed transformer, it had significantly better capability current wise, and was less expensive in the bargain.

I got to thinking that with this transformer, a 40w output transformer and a pair of 5881s and the existing Jensen C12K speaker, a Deluxe Reverb Reissue could deliver significantly more power out of the same package. A minor revision of the power supply capacitors might be in order as well.

I do not think the 6V6 output transformer would be optimum for this conversion because the impedance is 6.6k rather than the 4k that the 6L6 and its variants take.

It's going to be called the Avalanche. I've got a friend lined up who's going to donate a 68 Custom DRRI for the prototype. This could be some serious fun.

Back to the amp on the bench.

What had happened was a cascading failure. The 22 ohm resistor R69 in the bias chain failed open. I imagine the power tubes red plated and the rectifier tube and the power transformer both failed no doubt from overheating, which explains the no sound and bad smells.

The point here is, never miss an opportunity to check your raw voltages with the tubes out of the amp. That revealed the original source of the problem and had I not checked the voltages it might have been an expensive afternoon.

This revealed that I had voltage up to the 22 ohm resistor and nothing coming out the other side and emerging at the grids. You should know what pin it's on.

When all was said and done I had 425 volts on the plates and screens, and all that was required was a matter of changing the bias resistor R59 from 22k to 10k which is what is called for in the schematic.

A heat soak for about four hours while I was watching the Super Bowl festivities got me to a surface temperature of 133 deg f on the exterior of the power transformer and there it stayed. A bit warm but tolerable. A small fan like the ones from Kmart or Target or Amazon come to think of it might just hit the spot. Or, perhaps, a metal bracket with a muffin fan? Maybe.

Don't expect this to stay here forever. If it looks like I can make some dough on this you won't see it any more.

Trade secrets, y'know.