Need help figuring out this reverb driver transformer (Gibson e6400)

JW · Mar 8, 2017

Here's a scheamatic: http://i142.photobucket.com/albums/r106/capnjuan/gibson%20falcon/GibsonGA19MaestroM216.jpg

It's a Gibson Falcon GA19 RVT The original transformer was open, so I replaced it with an off the shelf fender reverb driver transformer (E 037099) that I bought off ebay.

I haven't been able to locate any information on either of these transformers though. Very frustrating. But I'm thinking it's very likely I put in an incorrect transformer as a replacement.

Problem is the reverb circuit fuzzes out way too early, around 11:00 on the reverb pan dial. I'd like to be able to crank it up even more when I want to.

I've tried swapping the 6C4 tube and I get the same result. The transformer primary is connected directly to the 6C4 plate and the reverb tank measures a low 185 ohm input impedance.

Can someone recommend the appropriate ratio transformer I should be looking for here? Or even a suitable replacement?

CJ · Mar 8, 2017

probably a 100:1 like the Fender transformers,

a lot of amps have full reverb as soon as you turn the knob, probably a sales thing,

measure the DCR of the input to the reverb pan, should be low ohms, other side should be higher, like 276,

maybe mod the makeup stage with a voltage divider, small caps can be used also to tweak the tone,

walter · Mar 9, 2017

I thought the Gibson Pan and Transformer was way different than Fender, but it's been awhile since I worked on one. You might try a Fender pan as a quick fix.

PRR · Mar 9, 2017

> the reverb tank measures a low 185 ohm input impedance.

That's a nominal 600r tank.

Fenders run 8r tank.

The get-er-done fix is to insert a stock Fender-like tank, then MARK the change on the chassis so later techs know it is changed.