As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) PILOT SAW SMOKE COMING FROM AVIONICS STACK. SHUTOFF AVIONICS, ELECTRICAL ETC, LANDED WITHOUT INCIDENT. MX DISCOVERED SOME HARWARE AND ELECTRICAL TRANSISTOR LOOSE IN TRANSPONDER CASE, SUSPECTED FROM THE TRANSPONDER. REPLACED TRANSPONDER WITH LIKE SERVICEABLE UNIT.