DavidRavenMoon wrote:OK, I got it working!
gtrgeek1 is correct... there seems to be nothing wrong with the original schematic (except for Q1's supply voltage being 8V and not 9V), and RG's PCB is correct.
So here's what I did... first there was the issue where on RG's layout sheet R22 and R27 are swapped. So I removed them and put them in the correct locations. That did little to help the Brass switch, but I at least heard something when I switched it. I had tried moving where R29 connected to C13, but I switched that back to the original location.
I decided to check Q6, since that was responsible for amplifying the output of the filter and sending it back to the circuit. I looked up the pin out for the Fairchild 2N5308.. voilà! I had it in backwards. It did match the layout as far as where the flat side was, but it had the emitter and collector swapped!
So I carefully unsoldered it and flipped it around.
Here's the results. First you hear the two settings of the Brass switch, then I flip the Harmonic switch, and then switch the Brass switch again. You go from very full to very thin, just like the real thing. The very thin setting is what Squire used a lot, as in the example I play from Close to the Edge, which has the dry signal mixed back in.
I don't have a real one in front of me to compare, but going from memory, this is pretty much nails the tones I remember using.