As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) CABIN CREW NOTED ELECTRICAL SMOKE EMANATING FROM THE PASSENGER SERVICE UNIT, PSU, AREA AT ROW 9AB DURING FLIGHT. FLIGHT CREW DECIDED TO RETURN TO BASE FOR MAINTENANCE PERSONNEL TO INSPECT THE ACFT. MAINTENANCE DISCOVERED ROOT CAUSE TO BE A READING LIGHTS POWER UNIT PN 8ES004514-01 TO BE AT FAULT. THE UNIT WAS NOTED AS OVERHEATED, BURNED AND MELTED. THE PSU WAS REPLACED AND OPERATION CHECKED SERVICEABLE. NO FURTHER FAULTS WERE NOTED.