As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
TRANSPONDER WILL NOT IDENT. RESOLDERED COLD SOLDER JOINT ON DIODE CR416. REPAIRED RECEIVE PROBLEM. FOUND -10 VOLTS ON -6 VOLT LINE. TROUBLESHOT AND FOUND C409 CAPACITOR DEFECTIVE. REPLACED CAPACITOR TO REPAIR -6V LINE. COMPLETED FUNCTION CHECK. ALSO INSTALLED Q415 HEATSINK AND REPLACED DETERIORATED RESISTOR R477. BENCH CHECK GOOD.