This pump shows signs of arcing and burn marks at the point the shielded power wire enters the pump. While checking inoperative video entertainment system problem, found buffer box NR 2 and NR 3 circuit breakers popped. Attempted reset resulted in sparks in video closet behind video equipment. Instrument lights failed. Two minutes later, the instrument lights circuit breaker tripped.
Pilot reset the circuit breaker.
Approximately four minutes later, the smell of smoke was observed. Aircraft was on final approach at this time and safe landing was accomplished. No evidence of flame inside or around light control unit. Apparent internal short of circuit board caused odor of burning wires and smoke. Loss of electric trim, autospeed brake and right generator was noted.