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.

sas-schematic SA5 schematic sketched for debugging

sas-front-annotated SA5 front view, manually assigned ref des

sas-back-annotated SA5 back view, manually assigned ref des