Hi
I've built the Neutrino black version with a PCB I etched myself. But I can't get any sound from the output. Should there be a short in place of the omitted diode (D4)? Also is C2 just left out (nothing in place of it)?
You may safely omit C2, but you do need to jumper D4 on the etched board. That shouldn't be killing your output, though.