'65 Reissue Twin Reverb - Fizzy on Rev/Trem Channel

[mikeboone]

I am looking at a reissue Twin Rev that's about 3 years old. On the rev/Trem side there is a distorted and fizzy sound at any volume. Problem does not exist on the Norm side. The Rev and Trem seem to function OK.

It also has a weird fizzled sound when a note decays as well, if that helps. Much like the sound decays when the amp is playing down when power is cut off.

The volume is normal, loud.

I looked at the schematic and worked through the preamp tubes starting at V2 ending at V5. Excluded V1 and V6 since the normal channel is, well, normal.

I will open it and measure/post the voltages soon, perhaps tonight.

In the meantime, does this sound like a common problem that any of you guys have seen?

Thanks,
Mike

[pdf64]

Does it have a valid waranty?

[mikeboone]

Does it have a valid waranty?

No, I wish. These were bought from Guitar Center as slightly used. They were used at Jazz Fest for back line and sold off afterwards.

[überfuzz]

Did you swap the tubes around. Start with a swapping of v1 and v2, with any luck it's just a bad tube.

[pdf64]

Ok, try removing V3 to see if that affects the fizz; weird things can happen with the reverb driver.
Other potential issues include a bad plate resistor and oscillation caused by a bad B+ or bypass cap.
The 5 years waranty is transferrable, provided that the original owner endorses it.
Pete.

[mikeboone]

Ok, try removing V3 to see if that affects the fizz; weird things can happen with the reverb driver.
Other potential issues include a bad plate resistor and oscillation caused by a bad B+ or bypass cap.
The 5 years waranty is transferrable, provided that the original owner endorses it.
Pete.

I did swap some tubes around but did not try it with the rev driver out. I am going to open it up tonight and plot all the voltages. I have a schematic that I got from Fender .com for the reissue Twin Rev. that has a lot of test point data as well.

Thanks for the input.