Can't get MXR Flanger to stop buzzing

[ugly_guitar_guy]

Hey guys, I've been trying to sort this Flanger for months now. Originally the switch was kaput, so I replaced it with a 3PDT so that I can later add a floating plexi LED plate for on/off indicator. Then it started buzzing when in certain positions. If it was face down it worked perfectly, if it was face up it buzzed like crazy. I thought it might have been the power chord, so I swapped it and that didn't change anything. I've uploaded a youtube video to show the problem. I've check all connections that I can check for continuity and everything seems to line up, so I'm a little lost. Any thoughts here?

Thanks guys, I know this is a vague problem to track down but I gotta get this thing fixed. It just sounds too damn good to leave like this!

www.youtube.com/watch?v=HnIgx3q2UbY

[LucifersTrip]

maybe not a bad joint or connection. it's possible an exposed wire is being pushed up against the case or part of the circuit... something that got jammed in there after you replaced the switch.

does it do the same thing when the circuit is removed from the enclosure?

you'll probably have to check the voltages in the "good" and "bad" state.

[cjlectronics]

Obviously something is micro-phonic and typically an inductor, or transformer in this case, is the culprit. If you feel the transformer case is well grounded ( I assume when you replaced the power cord you wired the ground terminal to the case) try these other ideas.
I've seen weird things happen where resistors cause noise and micro-phonics.  Try using a non-conductive stick and lightly tap various components to see if its possible to isolate an area on the board where the buzz is heard.
If this goes nowhere, try a can of freeze-it on various components while injecting a tone into the circuit so the buzz is heard. You might spray an area where the buzz stops.

[ugly_guitar_guy]

maybe not a bad joint or connection. it's possible an exposed wire is being pushed up against the case or part of the circuit... something that got jammed in there after you replaced the switch.

does it do the same thing when the circuit is removed from the enclosure?

you'll probably have to check the voltages in the "good" and "bad" state.

Took it out of the enclosure and it wouldn't STOP buzzing. It sounded horrific... Put it back in the enclosure and it was back to the same old problem.

Obviously something is micro-phonic and typically an inductor, or transformer in this case, is the culprit. If you feel the transformer case is well grounded ( I assume when you replaced the power cord you wired the ground terminal to the case) try these other ideas.
I've seen weird things happen where resistors cause noise and micro-phonics.  Try using a non-conductive stick and lightly tap various components to see if its possible to isolate an area on the board where the buzz is heard.
If this goes nowhere, try a can of freeze-it on various components while injecting a tone into the circuit so the buzz is heard. You might spray an area where the buzz stops.

I checked ground continuity with the DMM and everything was fine. tapped around the board with the stick and no matter when I touched I get that buzz so it's impossible to narrow down a source that way. Is it possible the SAD1024 is doing this?? I do have an extra, but don't want to wreck it if there's something on the board that's a problem.

[ugly_guitar_guy]

Just a thought, what's the chance this is a bad 3PDT? When I push the switch I get a rather loud pop...

[ugly_guitar_guy]

Nevermind! I fixed it FINALLY!!

In an act of desperation I shoved a piece of plastic between the pcb and the pots just  to rule out that they were somehow touching when the pcb was screwed down. No more buzzing! It's quiet as a church mouse and sounds fantastic! Very happy camper at the moment. Now I can add this and my mini tremolo to my pedalboard. 

Thanks for the help guys!