As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ELEC BACKUP SYS A FAILURE IN THE BACKUP ELECTRICAL SYS HAS OCCURRED THAT CANNOT BE ATTRIBUTED TO A BACKUP GENERATOR. FOUND BACK UP CONVERTER FAULTY IAW FIM 24-25-TASK 802. 28V DC PCN PRESENT AT PIN 1 OF CONNECTOR 24008, REF WDM 24-25-31. REQUIRED 566-9012 NIS GUM. PLACED CONVERTER 566-9012 ON PAC ORDER, REF OSTF T1501. REPLACED BACK-UP GEN CONVERTER IAW AMM. BACK-UP GENERATOR SYS SERVICEABLE.