Hi All, Here is a link to a schematic for the 3/4 A power supplies with the added parts for external voltage protection:
http://www.ameradio.com/doc/Astron%20RS-3A,%20RS-4A%20schematic.pdf John KN5L On 07/21/2016 07:41 AM, Myron Schaffer wrote: > It used to be that way....the RS linear models could not tolerate external > voltage present when unpowered, not anymore. Astron has incorporated > back-voltage protection through incorporation of some diodes installed in key > locations to prevent this. > > You can verify if your supply has this modification by looking at the circuit > board and see a 1N4001 type diode soldered across 2-pins (can't remember > which ones off the top of my head) of the IC voltage regulator LM-723 chip > and others hung in various places to protect the pass transistor as well. > Usually soldered to the solder side of the circuit board so they are easy to > spot. I can't remember is there were some small capacitors added as well. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
