First, clean all the connectors associated with this board. Over time they can get corrosion built up on them and they stop conducting. Use De-OXIT or Isopropyl alcohol to clean them. You may have to clean the deviation control on the board or replace C* and C10. I doubt if the microphone amplifier, Q1, is bad but if you can check the voltages around it, that might give you a clue. This problem shouldn't be too hard to fix as the rest of the radio is working. Good Luck!
Answers & Comments
First, clean all the connectors associated with this board. Over time they can get corrosion built up on them and they stop conducting. Use De-OXIT or Isopropyl alcohol to clean them. You may have to clean the deviation control on the board or replace C* and C10. I doubt if the microphone amplifier, Q1, is bad but if you can check the voltages around it, that might give you a clue. This problem shouldn't be too hard to fix as the rest of the radio is working. Good Luck!