What was found
WHEN CREW ENTERED AIRCRAFT AT GATE, WITH EXTERNAL POWER ON, THEY NOTICED SMOKE IN COCKPIT AND CABIN. THE NR 2 TRANSFORMER RECTIFIER CIRCUIT BREAKER WAS POPPED AND WOULD NOT RESET. EXAMINATION OF THE NR 2 TRANSFORMER RECTIFIER FOUND IT BURNT. THE NR 2 TRANSFORMER RECTIFIER WAS REMOVED AND REPLACED, OPERATIONAL CHECKS WERE GOOD.