What was found
(CAN) ENROUTE THE PILOT REPORTED A STRONG SMELL AND A FLASH OF LIGHT FROM CENTER CONSOLE AREA. THEY TURNED THE INTERIOR DOME LIGHT ON A CONFIRMED THAT A PLASTIC LIGHTING PANEL WAS MELTING ON THE RUDDER LIMITER AND STANDBY ELEVATOR BUTTONS. HE POKED THE SPOT WITH A PEN WHICH RESULTED IN FURTHER ARCING AND SMOKE. HE REQUESTED A LOWER ALTITUDE AND LANDED. MAINTENANCE WAS CONTACTED AND DISPATCHED TO THE AIRCRAFT. MAINTENANCE FOUND THE LIGHTING PANEL FOR THE TRIM HAD SHORTED. IT WAS DISABLED AND THE INTERIOR LIGHTING TESTED WITH NO FURTHER PROBLEMS. THE ITEM WAS DEFERRED AND THE AIRCRAFT RETURNED TO SERVICE. THE PILOT REPORTED THAT THE CB DID NOT POP AND THAT HE HAD A HARD TIME IN LOCATING THE CORRECT CB TO ISOLATE