What was found
AIR TURNBACK, NR 1 GENERATOR TRIPPED OFF IN CLIMB. UNABLE TO CONNECT AUX PWR UNIT TO BUS. NR 1 ENG BUS OFF LIGHT ILLUM IN FLT, WOULD NOT RESET. APU GEN WOULD NOT CONNECT TO NR 1 MAIN BUS THOUGH APU SHOWED 115V 409HZ. APU DID CONNECT AT GATE ON GROUND AFTER ARRIVAL BUT DROPPED OFF AFTER 3 MINUTES. REMOVED AND REPLACED NR 2 BUS TIE BREAKER FOR APU (BAD AUX CONTACTS) PER A8M24001. REMOVED AND REPLACED NR 1 GEN FOR NR 1 GEN TRIP FAULT PER R5M24002, ALL FUNCTIONS NORMAL.