Odd switch pop issue: Only when something's plugged into the In jack

[midwayfair]

I've got a pedal boxed up with a Multiplex, Rub-A-Dub, and Fatpants in series. Only the multiplex is on the bypass switch; the other two are always on.

At first it was popping without anything in the in jack. I removed the pull-down resistors from the Rub-A-Dub and Fatpants and now it only pops when something's plugged into the in jack.

I removed the boards one at a time and determined that the Fatpants is source of the pop, since I don't get a pop when it's not in the circuit.

This doesn't happen if I run three discrete copies of these pedals in series regardless of which ones are on or off.



Edit: Actually, I think I found the source of the problem: I've got power leaking to ground somehow. craaaaaaaaaap.
Edit edit: Actually, no I didn't. Hooked everything up to the bypass one at a time and in all three combinations, desoldered power from the ones that weren't in the circuit, and there was still a pop. Finally got really curious and disconnected the power and .... it still pops.

Welll..... that's freaking magical. 

[jkokura]

I would switch out my switch at this point.

Jacob

[midwayfair]

I would switch out my switch at this point.

Jacob

I did that, too.

Right now, I'm down to no boards in the box (with the LED being the only thing "bypassed"), but I ran out of troubleshooting time last night. I'm swapping out the DC jack next.

Although I thought it was the Fatpants, I've now confirmed that it really is somehow related to the tip of the input jack and its relation to .... well, I don't know. I do wonder if maybe it's from grounding the multiplex's input in bypass. I didn't think of disconnecting that at home.

However, I've decided that I'll probably end up cutting the trace to the rotary and wiring the pedal for tails. If I can get the switch to where it doesn't pop when bypassing just the LED ...

I'm starting to think there's a Gremlin in the box.

Edit: Once I get it working, this is totally being painted on the bottom lid: