Paragon Shorting on Enclosure

[ddavis20341]

I'm having some issues with the Paragon builds that I'm working on right now. I'm building 3 of them - 1 for me and 2 for friends - and all three of them are having the same issue.

They work fine out of the box, but when I go to put them in the enclosure, something shorts/grounds out and the signal cuts out. This is usually on channel 1 (2 of them have channel 1 cutting out, the 3rd has both channels), and additionally the tone knob on channel two then starts also controlling the volume. I was wondering if the tone pots are where the pedals are grounding, so put some electrical tape over the tops of the legs and also over the 3 holes right below the shaft, but that didn't seem to make any difference.

It seems to only happen as well in the last third or so of tightening down the components - everything works fine until you hit a certain depth, at which point you can hear the tone change from the tone part starting to control the volume, and the channel cutting out.

Just wondering if anyone has any tips/has encountered this before. I'm a little bit stumped right now since I don't see anywhere obvious for things to be grounding out. I also have plastic seals on the bottoms of the pots, and have tried re-flowing a bunch of the connections to see if that makes any difference. Thanks!

(Sorry for the bad lighting in these pics, I can upload better ones if needed)

https://imgur.com/a/tR8hEsN

 

[ddavis20341]

(For reference, I also looked at this, but that problem didn't really have to do with the enclosure it sounded like)

 

[Robert]

Are you using metal LED bezels?

 

[ddavis20341]

Yes I am! Let me try taping off the end of it and see if that fixes things.

 

[ddavis20341]

Wow, you're totally right - I haven't turned it on yet, but just visually looking at it, I can see that the bezels look like they're touching the tone pots.

 

[ddavis20341]

No dice so far - I tried a piece of electrical tape across the bezel, and then after that tried one around the legs of the pots. I'm going to try taking the bezels out to confirm that's actually the culprit.

 

[ddavis20341]

Okay, that seems to have done it. What else can I try to better isolate the bezels? Just a lot of tape?

 

[Gordo]

Either cut/file them down so they clear or switch to plastic. If they're the ones I'm thinking of they have a short crown of about 3/16" or do that isn't threaded that could likely be removed.

 

[ddavis20341]

Filing them down did the trick! Thanks for the suggestion.

The last hurdle in these builds now is a pretty audible pop when engaging or disengaging the pedals (audible on both channels). I just checked and saw that I have between 50 and 250mv on the output jack when the pedal is engaged (which seems like a huge amount of dc to be getting through). Double-checked the value and orientation of all of the caps and diodes, everything seems to be in order there. Values for pull-down resistors are also correct.

Any thoughts? I saw this on adding an extra cap to tame it.

 

[phi1]

I’d guess it’s the 1u electrolytic (in parallel with the 1u film). Electrolytics can leak dc through, and I’ve had that exact issue a few times. I’d try replacing the electrolytics with film.

Moreover, you could probably just clip the electrolytics off without replacing them, by my math the 1u film ought to be plenty to let all low frequencies through.

 

[ddavis20341]

Worked like a charm, the issue is totally gone now. Thanks for all of the help, you all on this forum are awesome!