Microphonic pedal?

[claytushaywood]

My sea urchin delay has been a real pain... all of a sudden it stopped working yesterday and just started humming really loud when on.  I tested continuity and realized the dc jack wasnt making ground contact to the enclosure- dont know why or how this happened... all of the ground connections seemed to be making connection.  I added a ground wire and it fixed the problem.  worked fine!

now today the pedal is acting like its microphonic-  when i step on it it's popping majorly,,, not just when i engage the footswitch but when there is any contact made.  if i gently press the footswitch it wont pop.  but when I have the back off just touching the edge of the board or even the knobs from the outside i get pops.  i can just hit the enclosure and it pops.  sometimes the effect cuts out and i hit it again and it comes back

I've heard of microphonic capacitors, could this be it?  or is it a ground loop?  loose connection?

anyone got a likely scenario?  I did add a switch to change one of the filtering caps so I can get a choice of how dark the repeats are.  Also, the mix knob doesnt seem to be functioning correctly... it doesnt get as quiet as it used to, and the feedback knob above noon sends the repeats into oscillation (after a couple seconds)

I've never had a problem like this!  Any help would be greatly appreciated!  Sorry I cant post pictures of the board right now

[claytushaywood]

can  anyone tell me what components are most likely to be microphonic?  are pt2399's prone to this?  I know ceramic caps are prone to microphonics... but I didnnt use any in this build- used polystyrene.  what about electroltyics?  it really seems like one of the pots is... is that possible?

[stecykmi]

i would say you have a loose ground connection somewhere. outside of vacuum tubes, electrical components aren't really affected by vibration (why would they? they have no moving parts).

check all your solder joints again, especially ground and +9V connections. reposition/tighten all your hardware to make sure they're making good connection to the case, and double check the solder joints on your pots.

[pickdropper]

i would say you have a loose ground connection somewhere. outside of vacuum tubes, electrical components aren't really affected by vibration (why would they? they have no moving parts).

check all your solder joints again, especially ground and +9V connections. reposition/tighten all your hardware to make sure they're making good connection to the case, and double check the solder joints on your pots.

+1.  I had a pedal that exhibited this sort of behavior.  Turns out that the input and output jacks had loosened over time.  The input was hardwired to ground, but the output relied on a tight connection to the chassis.