These are the service manuals for a number of Astron power supplies. These workhorses are built solid for years of constant service in radio communications and other applications. The linear models use a very simple design, and any problems which occur with them can usually be remedied by the replacement of one of the (socketed for your convenience) 2N3771 transistors on the back heatsink, or the large electrolytic capacitor inside. Should you need the schematics, though, here they are. 

Please see astron-rm50a-bb.jpg for a VERY useful standby backup battery circuit! Power goes out, radios stay on! (If you build and add this to your PSU, please adjust the variable resistor inside to set the output voltage present at the battery terminals to 13.80 volts with no battery connected. This is the optimum float charge voltage for a lead-acid battery.)

See more useful information on Astron supplies here. 
 
https://www.repeater-builder.com/astron/astron-index.html