You can get access to the schematic through the Rider Index on this website. You will first get page 1. The information you want is on page 3 (change ..17.1.. to ..17.3.. on the address line of your browser and click go. This will show you that pin 1=antenna, pin2=ac line antenna (can be strapped to pin1 in place of external antenna), pin 5 is a phono input, pin 6 is chassis (common) and pin 7 is the output. When the tuner is turned off, the phono input is fed to pin7, otherwise pin 7 is the tuner output.