Gretch 6162 reverb pan replacement ?

[1ampman]

Originals are short and in a cardboard box held down by sping. The pan is bad. I've tried other long pans and can't get a peep out of it.....I do realized it has 2 shut-off switches.

[52 Bill]

Do you have a schematic?

Is the tank driven through a cap, no transformer?

[1ampman]

Yes I have schematic and it is transformer driven. They use both sides of a 12ax7 to drive the transformer. I scoped the signal in to pan but signal out is very little. I've tried some higher impedance pans from a Traynor and made no difference . PIA.......

[Enzo]

I think that might have been a hint to post the schematic...
http://bmamps.com/Schematics/Gretsch/gretsch_6162.pdf

Looking at it, I would expect the lowest impedance pan to be your choice, like a 4AB2C1B. Higher impedance drive sides won't go where you want.

Isolate the problem. COnnect a speaker to the output of the drive transformer - instead of the reverb pan. Do you hear signal in that speaker? That tests the drive. Pull the cable from the pan output and touch the tip of the plug with your finger, and have the reverb up midway. Does that make a loud hum? That tests the recovery.

You can connect the drive to the pan input and run a cable from its output over to the input of some other amp. Do you hear reverb through that other amp?

If you rock the amp to crash the springs, does THAT make a loud sound out the amp?

You want to see the pan output signal? Just sit the pan on the bench, springs up, not connected to anything, hook your scope to the output jack on it. Now run your fingers along the springs. You know that would normally be loud. Well, that is what a loud reverb signal looks like on your scope.

And that mixing circuit is sure unique. MAke sure the pot is 500k like it should be, and no one has put a wrong value in. In fact, make sure the reverb return switch is open, and measure resistance across the 500k pot. It looks like it ought to go from about 80k down to zero as the pot travels.

[52 Bill]

Yes, thanks for the link Enzo.

Interesting footswitch design, open the secondary load on the reverb drive transformer.

[Enzo]

I THINK the idea behind two reverb kill switches was that the one on the panel did not have to interact with the footswitch. Most amps with a panel switch and a footswitch, put them in series or some other convolution so they can work together. This is simple.

[52 Bill]

Yeah, but I thought that the dumbest idea would be to run a power amp with a transformer, albeit a tiny one, without a load. Isn't that tube design no-no #1?

[Enzo]

Well, I see it as a matter of scale. That tiny circuit probably cannot damage itself like a huge OT with 500v on it. I have seen tube amps with the pans out for decades and have yet to see one kill the transformer. I may have replaced three reverb transformers in Fender in the last 30 years. I doubt that is what killed them.


You get better gas mileage in a car with streamlining and reduction of air resistance. But I suspect in something like a Caterpillar tractor, it won;t make any difference. To slow for air resistance.

I swear that sounded like a good analogy when I typed it out.