What was found
KPSP - KLAS TRIP ID# 743429 CREW REPORTED THAT THEY HEARD A POPPING SOUND COMING FROM THE CIRCUIT BREAKER PANEL. ARCHING HAD OCCURED FROM THE BOTTOM OF THE CIRCUIT BREAKER PANEL FOLLOWED BY A NOTICABLE SMOKEY SMELL. APPROXIMATELY TEN SECONDS LATER THE ARCHING HAD EXTINGUISHED AND VAPOR HAD CLEARED. THE CIRCUIT BREAKER PANEL LIGHTS WERE FOUND TO BE INOPERATIVE, AND A SMALL MELTED AREA ON THE PANEL WAS HOT TO THE TOUCH. THE LIGHTING FOR THE PANEL WAS ISOLATED AS WELL AS THE HEAT SOURCE WHEN THE CIRCUIT BREAKER FOR THE PANEL LIGHTING WAS PULLED. THE FLIGHT PROCEDED WITHOUT FURTHER INCIDENT. MAINTENANCE ISSUED MEL 33-6 FOR THE CIRCUIT BREAKER PANEL LIGHTING.ON 14 JANUARY, 2005 MAINTENANCE REMOVED AND REPLACED THE