Marshall G80RCD Input Jack Replacement

[misterc57]

I am trying to understand the odd input jack (that needs replacement) on this amp. This amp is not worth much due to cosmetics and if possible I would like to use a standard or shorting jack I have in stock. Otherwise I did find one at https://www.amprepairparts.com/marshalljacks.htm

Seems like one of the ground runs goes to a 1M resistor to ground. I do not understand the purpose of all the connections to the jack.

With the plug inserted I am thinking there is only a connection to R114 and to ground?

Schematic attached.

Thank you

Marshall+G80RCD-G100RCD.pdf

[The Dude]

That amp uses the ring contact and switch to ground signal in the preamp. It's not the traditional setup where the input itself is grounded when no plug is inserted. Why not just install the factory part?

[dmeek]

The switch shorts the gate of Q1 to ground to mute the amp. Schematic could be improved.

[misterc57]

And now another G80RCD input jack mayhem. Found this when I got the board out, since removed the jack. I will order a replacement jack. Not sure if I should try to fix the pads, via, traces or run wires from the new jack to the board.

Any thoughts on this repair? Thank you, Mark

[g1]

Due to the way the board mounts to chassis, I don't think you will be able to run wires. I think you will have to fix the traces.

[The Dude]

I agree. Best to fix the torn traces running small wires where necessary. Also, seeing all the ripped up traces, the jack itself may not even be bad. You can easily check it with a meter, since there is a diagram right on the jack itself.

[misterc57]

Reused the existing input jack. Not a proud soldering job. Amp has noise so opening a new thread.

Thank you