Finally! I’ve been debugging a serial port on a new controller for days. I’ve made dozens of these things and there’s not at lot to it. This was making me a bit bonkers. It ended up being a sharp point on a bottom on a chip socket that was poking through the insulation of a wire and intermittly applying 12 volts to the attention line. The wire was moved and sharp point clipped, and a few more gray hairs added. I guess that’s what testing is for. This one will fly on Away 36 this summer.