I went to the Kitsap ARC hamfair in Silverdale, WA on Saturday. I found this RS-50a for $70, the seller mentioned the crowbar circuit was removed and I thought nothing of it, after further inspection, two of the 2N3772's are missing. So not quite the hamfair or hamfair deal I was dreaming of.
One thing for sure, it is a basic power supply and seem to be lots of info out there in regard to the Astron power supplies. I first plugged it in and watched the voltage go up to almost 18vdc! Glad I didn't plug a radio into it. After a few minutes of the voltage jumping around it settled down to a solid 13.8vdc. First fix attempt was replacing the LM723 voltage regulating IC.
Being a little older, this regulator board had the LM723 soldered directly on the pcb. I de-soldered the IC and installed a 14pin socket, making IC replacement easy. I have a few Astron power supplies so I tried one of the known good LM723, and still had the power on voltage problems! So still not trusting this supply, even though after about 5 minutes of being plugged in, voltage flattens out. I have a few ideas of where the problem could be, and I'll continue to work on it until I know it's perfect.