What was found
CREW CALLED MAINTENANCE WHILE AIRCRAFT WAS AT GATE, STATING THEY SMELLED SMOKE IN THE CABIN. MAINTENANCE FOUND THAT A LIGHT BALLAST ABOVE ROW 19 DEF HAD GOTTEN HOT AND SCORCHED THE OVERHEAD BIN. ALSO, THE PSU CENTER LIGHTING CIRCUIT BREAKER IN THE COCKPIT WAS FOUND POPPED. MAINTENANCE FOUND THAT A WIRE RUNNING ABOVE THE SAME OVERHEAD BIN HAD GROUNDED. THE BALLAST WAS REPLACED. ALSO, THE ADJACENT BALLAST WAS REPLACED AS A PRECAUTIONARY MEASURE. THE OVERHEAD BIN WAS PULLED DOWN AND THE CHARRED WIRING WAS REPLACED AND THE INSULATION WAS REPAIRED.