I thought I'd post a little pictoral of the board revs to-date. We start off with the original board layout (unlabeled Rev A):
You will notice a few unfortunate jumpers: I didn't have a good way to cross the Arduino data lines, so I jumpered the +/- 15V. Also, in a last minute change, I ended up tying three data lines to ground (those are the jumpers running to the left). New rule of thumb: Don't do last minute changes!
Fixes were applied, leading to the Rev B board:
This is working all right, but doesn't do any cleanup of the power, and had really, really big mounting holes. Rev C was next, but it was a total dud - I got so ticked that I chucked 'em all! Rev D is the current board:
Now I've got some caps and diode across the power lines (hopefully preventing future bursts of smoke coming from the Nanos...), and I've replaced the analog input connectors with 3-pin MTAs so that they can be user-swapped as pots, switches, jacks or push-buttons. I want to do a little more power supply cleanup, then we are probably to 1st version production boards. Hurrah!