What was found
GUM - FLT 958 - SITTING AT GATE WITH APU RUNING, APU ELECTRICAL POWER KICKED OFF WITH A PHASE UNBALANCED LIGHT ON, ON ELECTRICAL FAULT PANEL. SHORTLY THEREAFTER, ELECTRICAL SMOKE IN COCKPIT. FOUND T3 TERMINAL ON 'A' PHASE FEEDER CABLE BURNED AT APU GENERATOR CIRCUIT BREAKER T3 TERMINAL. REPLACED APU GENERATOR CIRCUIT BREAKER AND REPLACED 'A' PHASE TRANSFORMER. REQUIRES TERMINAL END TO CONNECT 'A' PHASE FEEDER CABLE TO TERMINAL T3. UNABLE TO LOCATE. PLACARDED APU GENERATOR PER MEL 24-01-2. (M)