As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTS THAT MULTIPLE SYSTEMS AND ANNUNCIATORS UNSERVICEABLE. MAINTENANCE PERSONAL DISPATCHED AND FOUND THAT NR 1 DUAL FED ELECTRICAL BUS HAD FAILED BOTH MAIN FEED DIODES (P/N 70H10A). DIODES REPLACED AND FUNCTION CHECKED SERVICEABLE. COMPANY HAS NOW IMPLEMENTED A MONTHLY REPETITIVE CHECK OF THE BUS SYSTEM DUE TO THE DORMANT FAILURE RISK OF THESE DIODES.