As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
KT76A TRANSPONDER FAILED IN-FLIGHT. TRACED PROBLEM TO FAILED RESISTOR MODULE RM402 ON MAIN CIRCUIT BOARD. ACCOMPLISHMENT OF AD 98-14-03 (BENDIX/KING SB K7-76A-7). REPLACED RM401 AND RM402 AND REPAIRED UNIT. RE-INSTALLED UNIT AFTER REPAIR/AD COMPLIANCE AND TESTED GOOD IN AIRCRAFT USING ATC-600 PUMP TESTER (FAR 91.413). RM 401 AND RM402, P/N 015-00045-0001.