What was found
(CAN) WHILE ENROUTE, THE FLIGHT CREW NOTICED AN ODOR LIKE PLASTIC MELTING. THE FLIGHT CREW AND F/A LOCATED THE SOURCE OF THE ODOR TO BE THE ATTENDANT PA CONTROL PANEL. THE PILOT PULLED THE RELATED CIRCUIT BREAKER FOR THE PA SYS AND THE ODOR WENT AWAY. WHEN THE ACFT LANDED MAINTENANCE STAFF INVESTIGATED AND CONFIRMED THAT THE ATTENDANT CONTROL UNIT WAS AT FAULT. IT IS SUSPECTED THAT THIS UNIT MAY HAVE FAILED DUE TO WATER INGRESS, IT WAS RAINING HARD DURING THE PREVIOUS STOP, WATER MAY HAVE CONTAMINATED THE UNIT WHILE THE PAX DOOR WAS OPEN FOR PAX BOARDING. THE UNIT WAS REPLACED AND THERE HAVE BEEN NO RELATED ISSUES REPORTED SINCE.