Replacing a PCB-mounted pot

[weiss2040]

Hi,

I have a broken pot on my Marshall lead 12, little solid-state amp made in the late 80s. I bought a replacement pot knowing little about actually replacing it, and was thrown for a loop when I saw it was connected to the board. I was told that kind of replacement was more difficult, but I still wanted to see if I could do it without taking it in. Any help would be greatly appreciated!

Dan

[52 Bill]

Do the pots panel mount through the front panel with lock washers and nuts?

If they do, you can connect the one that you have with short jumper wires.

If they don't panel mount, you may be able to rig up something, but at that point it will be better to buy the correct replacement pot.

[weiss2040]

The pots do mount through the front panel with nuts and washer, and I took those off for easier access to the board. I have the chassis out and everything, but just thought I would be un-soldering the old one and re-soldering a new one. But the nodes of the pot are connected directly to the board. Sorry I'm not familiar with the jumper wire technique you speak of, but hey I'm willing to try anything. Thanks.

[52 Bill]

If you look at the two pots, you'll see that they are basically the same with the exception of the legs. One has legs that are designed to have a wire soldered to them and the other has legs shaped to fit into a pc board.

Carefully remove the original pot from the board using whatever desoldering equipment that you have. Now, if you hold the new pot in position where the old one was, you will find that the shaft will or will not align with the other pots. If it does fit in the same general space, you will need to use short wires to connect the new terminals to the pc board, where the original one were soldered to.

If the pot will not align correctly you will probably have to turn the pot 180 degrees, so that the legs point away from the board. If this is the case, the wires that you use to connect the new pot will have to be longer.

Once you've soldered the new pot in, replace the board and use the correct mounting hardware to mount the new pot through the front panel. It will look the same from the outside as the others, but it will not be mounted directly to the board.