What was found
AIR TURN BACK. DURING FLIGHT LOST APU WITH NR 1 GENERATOR ALREADY ON MEL. AIRCRAFT RETURNED WITHOUT FURTHER INCIDENT. MX REMOVED AND REPLACED NR 1 IDG IAW AMERICA WEST AIRLINES TASK CARD R5M24301. OPERATIONAL CHECKS WERE GOOD. PLACED THE APU ON MEL. TEAR DOWN REPORT CONFIRMS REASON FOR REMOVAL. UPON TEAR DOWN, FOUND TWO LEAD WIRES BROKEN ON THE EXCITER ROTOR. THIS STOPPED RESISTANCE FLOW AND OUTPUT TO THE CORRESPONDING PHASES, TRIGGERING THE IDG OFFLINE. UNIT WAS REPAIRED IAW CMM 24-11-79 REV. 18.