Marshall MG series Reverb switch MOD

[spartadrive_in]

More specifically I have the MG100DFX but they are all similiar.

I'm looking for a mod that will enable me to put an on/off bypass swtch for the onboard reverb on there. As you know it only has a Level knob for it. Moreover, enabling that switch to be taken to a footswitch.

A schematic would be helpful but if someone could explain how well enough then I can probably manage.

And I have had experience in and know the dangers of working with amplifiers.

Thank you.

[Enzo]

For the last 50 years, Fender amps have killed the reverb by shorting across the return cable. There is no reverb pan here, but there is a reverb output from the DFX card.

How about a short across C42. Myself, I;d use a JFET controlled by the footswitch insted of a tap on the signal line running out there.

Or you could add a JFET in series with the signal exactly the same way they turn the effects off and on. Betweeen C7 and VR13.

or use relays instead of JFETs if you like.

[spartadrive_in]

I was thinking of using a mechanical footswitch. DPDT so I can add an LED indicator. Should still be ok right? And by "killing" do you mean just short the signal to ground?

Also, wiring diagram for the JFET option?

[Enzo]

You can use a mechanical switch, but you would be tapping directly into the signal path with wires running outside, so you have potential noise nad hum issues, be forewarned. That is why I prefer relays or JFETs or something that can be turned off and on remotely.

Crate amps are full of JFET switching, steal a circuit there. I am not prepared to draw up a circuit and scan it and post it at the moment. I have a lot of repairs to finish here.

By killing I mean turning it off, preventing its sound. In the case of Fender it was shorting to ground, but look at the FX control just under the reverb circuit on the amp schematic for yours and see that it is killed by opening a circuit.