In the process of troubleshooting a broken controller, I decided to sketch the circuit schematic. It was a real fun exercise, seriously, and the results are below. Next post will be my guess at the theory of operation. I already have figured most of it out, but I want to make a few measurements before saying I fully understand the circuit.
SA5 schematic sketched for debugging
SA5 front view, manually assigned ref des
SA5 back view, manually assigned ref des