Twin Reverb 65RI Reverb noise problem

[Badfish]

Hello there!
I’m hoping I could find a solution here if anyone experienced the same problem with their Twin Reverb 65RI having a very noisy reverb circuit.

Whenever I engage the reverb on and turn on the knob it just produces a loud hiss noise that gets louder as I turn the reverb knob more.
When I turn the reverb off the noise stops. The trem works fine without any issues.
I already searched around and tried different solutions such as replacing both the reverb send and recovery tubes, tried using a different footswitch, and of course checked & cleaned the circuit, spring reverb unit itself and its connections - but nothing helped and the reverb is still just produces noise.
I have a strong suspicion that it has something to do either with the footswitch jack area of the circuit or the reverb circuit itself but everything seems fine there.
I’ll be grateful for some wisdom if anyone here had the same issue with their Twin, cheers!

[GilmourD]

Hello there!
I’m hoping I could find a solution here if anyone experienced the same problem with their Twin Reverb 65RI having a very noisy reverb circuit.

Whenever I engage the reverb on and turn on the knob it just produces a loud hiss noise that gets louder as I turn the reverb knob more.
When I turn the reverb off the noise stops. The trem works fine without any issues.
I already searched around and tried different solutions such as replacing both the reverb send and recovery tubes, tried using a different footswitch, and of course checked & cleaned the circuit, spring reverb unit itself and its connections - but nothing helped and the reverb is still just produces noise.
I have a strong suspicion that it has something to do either with the footswitch jack area of the circuit or the reverb circuit itself but everything seems fine there.
I’ll be grateful for some wisdom if anyone here had the same issue with their Twin, cheers!

Does it do it with the reverb tank disconnected?

[Badfish]

Does it do it with the reverb tank disconnected?

Yes, that’s why I think it comes either from the footswitch jack area or the reverb circuit on the amp itself, perhaps a grounding issue?

[GilmourD]

Does it do it with the reverb tank disconnected?

Yes, that’s why I think it comes either from the footswitch jack area or the reverb circuit on the amp itself, perhaps a grounding issue?

Well, the switch issue COULD BE a grounding issue since all the switch does is complete the reverb circuit by connecting the other side to ground.

[andy_tchp]

The reissue is different from AB763/vintage (surely, hopefully?!) in the way it handles the reverb switching isn't it?

IIRC vintage models route the reverb signal through the footswitch wiring. (Thanks Leo! )

If the reverb is properly non-functional and only produces noise I would be pulling the tank itself and having a look. The wiring connections to the transducers is pretty light gauge and not uncommon to break.

[GilmourD]

The reissue is different from AB763/vintage (surely, hopefully?!) in the way it handles the reverb switching isn't it?

IIRC vintage models route the reverb signal through the footswitch wiring. (Thanks Leo! )

If the reverb is properly non-functional and only produces noise I would be pulling the tank itself and having a look. The wiring connections to the transducers is pretty light gauge and not uncommon to break.

I'm 99% sure that the only circuit changes are the death cap and with it the three prong power cable.

65 Twin Reverb Reissue Service Manual https://imgur.com/a/stov98D

[Badfish]

The reissue is different from AB763/vintage (surely, hopefully?!) in the way it handles the reverb switching isn't it?

IIRC vintage models route the reverb signal through the footswitch wiring. (Thanks Leo! )

If the reverb is properly non-functional and only produces noise I would be pulling the tank itself and having a look. The wiring connections to the transducers is pretty light gauge and not uncommon to break.

Did that already - the tank and wiring seems fine, and its noisy even with the tank disconnected, so I’m quite clueless here