Once again, a big thank you for pointing this out to me. I finally re-wired with a different switch today and it definitely works as it should.Unlikely as the ring of a stereo jack gets connected to the sleeve when a mono jack gets inserted. This is very commonly used in basses with an active eq to disconnect the battery when the jack is removed. So in your case that would mean both pups would be connected to ground leading to zero output.
Here's a stereo jack with stereo plug inserted:
View attachment 4307014
Now here's the same jack with a mono plug inserted:
View attachment 4307015
You can clearly see connection 5-Right being shorted to 1-Shield.
If you were to have an on-off switch between 5 and 2, putting the switch in on position would connect both 2 and 5 to 1 since 5 is already connected to 1.
With an active eq what's done is that 5 is connected to the negative battery pole. With the jack removed it would not have a negative connection to the eq, thus as if there's no battery. Inserting the mono jack would connect the negative pole to the eq meaning activated eq.
With an SPDT switch it would be like this:
View attachment 4307026
with the stereo jack inserted it would have to be in the B position to have stereo output.
with a mono jack inserted it would have to be in the A position to have both pups connected to mono output.
I’m getting old. My mind isn’t as sharp, shaky with the soldering iron and eyes…
You were a big help.


I'd never really thought about it. While I rarely pick it up, I'm rather proud of it, and am loathe to part with it.