What was found
ORD - CREW REPORTED LEFT OVERHEAD LIGHT BALLAST BEHIND ROW 8AB FAILED WITH FUMES AND ELECTRICAL SMELL. PER EMERGENCY PROCEDURE, PULLED CIRCUIT BREAKERS L6, J7, L19, L20, L21 AND F6. EMERGENCY DECLARED FLIGHT RETURNED ORD LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REPLACED LEFT OVERHEAD LIGHT BALLAST. SYSTEM GROUND CHECK NORMAL OPERATION.