[islesailor]

I added a jack for a bluetooth reciever to my 37-650x, it works fine. Should work for your phono. Mount a jack aand a spdt on the rear of your chassis. Since the radio is mono you need to combine the stereo channels. Connect a 1K resistor to each side of the jack. Connect the 1K resistors together and to a 1 Meg resistor. Connect the 1 Meg to ground. Connect the junction of the 2 1K and the 1 Meg to one side of the SPDT switch. Disconnect C33 (.01) from the junction of R31/R32. Connect C33 to the center terminal of the switch. Connect the other side of the switch to the place where you disconnected C33. Connect the third pin on the jack to ground.
Enjoy
Kelton
W4IND