Hi all, I have an 1982 M20J. It has a radio master switch (right next to the master power switch) and it also has another switch/CB under the panel that is a bypass to the radio master in case the radio master dies. Here is the scenario I experienced last week: 1. Master & Radio master OFF, bypass switch in normal position as it has been for 200+ hours. I turn on the master switch (radio master still off) and all avionics come on. I change position of the bypass swtich with no change.