Distortion pedal volume/noise jumping around, can't figure out why

[karbomusic]

How long did it take for the CNC to do that by the way?

About 10-15 minutes...the feed speeds need to be pretty slow for a smooth cut in the copper.  If you go too fast it's a really rough cut, and there are tons of copper slivers that would make debugging life miserable!

The longest part was putting the circuit board design together in Diptrace, and that wasn't too bad because I had an existing layout to follow.

That isn't bad at all. It's pretty much equal to the time I spend on an etch. My etches used to take more like 30 minutes but I built a little computer controlled 'wave machine' a few months back which cuts the etch time down to 12-15 minutes. If I lightly brush it constantly with a sponge that goes down to 3 minutes or less but it was the being engaged, work and mess I wanted to avoid so the DIY machine allows me to etch quickly while unattended.

[J0K3RX]

I like the CNC, looks really clean... fine tune it and get the correct drill bits and you'll be golden

Don't think you have a solder issue but it's possible.. I think it may be one of the 1uf electros you have on your build. I almost always use the poly film or box type caps when they are 1uf and they are in the signal path. I would remove all of those 1uf electorlytics and replace them with 1uf mylar or box type...  or, something other than the electrolytics   

Notice.. Wampler uses the poly film in the signal path

[canman]

Now that's something I hadn't considered...the other builds I've done I used film, not electrolytic.  In the layout, it showed electrolytic so I used those. 

As mentioned before, I don't have a meter that will measure caps.  Seeing as these caps are part of the signal path, I could use an audio probe to see which cap first causes the problem, correct?  (I'd want to continue the process until I've eliminated all possible 1uf cap suspects, naturally)

[karbomusic]

You might also (if you haven't already) check that the existing electros are all oriented properly polarity wise. Long shot, worth checking.

[J0K3RX]

The polarity looks correct in the pic on the first post... I would check the one hangin off the volume pot first 

[canman]

I checked the polarity several times, didn't see anything crazy.  I'll look again.  (Last time I got the polarity wrong, it went boom haha)

As I was prepping for the audio probe session, I couldn't get the stupid thing to act up.  Naturally.  So I started messing with the 1uf caps, just to see if I could prompt the issue again.  Here's the weird thing.  When I touch the tops of all the caps, nothing happens, except when I touch the 1uf cap coming off pin 14 of the TL074.  If I'm not touching anything metal on the guitar, the hum gets LOUD.

When I'm touching strings, hit a chord, and then touch the top of the cap...volume drops.  Just like in the video.  I'm wondering if that cap is the suspect.  Could the cap be faulty?  Should a capacitor make noise when you touch the top of it?  (The little metal disk there on top)

[GibsonGM]

They CAN act like an antenna, kind of, and do odd things.  At that point, you're thru 4 gain stages...but, like Jok3rx was talking about...at this point I'd go ahead and change the 1u, just because I have extra caps around, and it is mimicing your problem. Could be a long shot, OR it could be the problem!      Make sure of the polarity orientation, of course. 

One check I'd make first is to see what pin14's output voltage is (DC), and see if you read a DC voltage outboard of the 1u cap...if you do get something, be advised that the NEXT 1u down the line could be leaky rather than the one we're talking about...

[canman]

So, I was mistaken in regards to which cap was acting like an antenna.  It was the cap AFTER the one I referred to.  But either way, I tested both voltages, and both are reading minimal DC voltage outboard.  I also replaced the cap in question with another electrolytic, just to see if the antenna issue was just that cap, but it happened with the new cap too.

The bummer is, the CNC machine is having a motor issue and I'm not sure if I'll be able to engrave a new board for a while.  Which means, I need to get this stupid thing dialed in!  I'll see if I can generate the noise issue tomorrow and trace the signal and hopefully identify the culprit.