As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE COMING FROM FL BUTTON ON TRANSPONDER. TURNED TRANSPONDER TO STBY AND SMOKE BEGAN TO DISSIPATE. PULLED CORRESPONDING ATC CBS AND NO SMOKE WAS NOTED. DURING INSP NOTED THAT FO LIGHTING CB ON PEDESTAL POPPED. REPLACED TRANSPONDER PANEL. AFTER CONFIRMING PANEL SMOKED. TRANSPONDER TEST GOOD CB RESET LIGHTS TEST GOOD. NO FURTHER INCIDENCE OF SMOKE.