Hello Ben, what you're looking for is at : http://www.wb4hfn.com/DRAKE/DrakeManuals/L4B/Manual_L4B.htm Go to page 27. Best regards Guillermo - LU8EYW. SM6CKU escribió: > I am looking for the schematics of this power supply. Tried http://bama.sbc.edu but nothing found. Got the PSU some twenty years ago and it has never been used I assume. > Anyone with an advice? > 73 de Ben SM6CKU