BB-type build with opto bypass - footswitch pop = leaky couping cap?

[Bret608]

I did a BB-type build recently and am getting some intermittent footswitch pop, even though I used an opto bypass that should prevent that. Checking for voltage at the circuit in and out, I see that there is voltage on the output going from 0v up to just over 1mv. It sort of builds up slowly and then goes back to zero if I actuate the switch a couple of times. That sort of tracks with what happens when I'm playing--the pop will get louder and louder then go back to totally silent switching for a bit. Sounds like a leaky coupling cap based on my reading on the matter. Would anyone be able to take a look at this schem and tell me which are the coupling caps? I'm suspecting the two electros of course, but am not sure if there are others to check out. Forgot to mention, there is never any voltage on the circuit input.

 

[jubal81]

That design has some issues. DM me and I'll PIF you my Ubu Roi. It's been in the closet for a while, so it's a little dusty.
All the options are on the control plate and it corrects the signal inversion.

 

[Bret608]

I would not have guessed there is anything fundamentally off with the design! Will DM you shortly...

 

[moonlighter]

Do you have a schematic for the opto bypass? Are you using H11F1M modules?

C1 and C9 are the coupling capacitors.
A common trick to reduce popping is adding a 1K resistor in series with your output; one leg to R10, the other to your board OUT.
It also seems R10 in your schem is a 1M, which much too high IMO, 100K would be more sufficient. The high resistance is keeping C9 from discharging any trickle current.