What was found
WHILE ATTEMPTING TO START APU, GOT AN APU FAULT, THEN ELECTRICAL FUMES AND SMOKE IN COCKPIT PULLED APU/ START C/B. OPEN FRONT PANEL OFF OF 120 VU, INSPECTED WIRING, AND APU START CONTACTOR 5KA, APPEARS TO BE IN GOOD SHAPE, NO DAMAGE, 50 AMP BREAKER 10XH POPPED AND WILL NOT RESET. ATTEMPTED TO START APU TWICE AND RECEIVED APU FAULT. RPM NEVER ABOVE 17% AND EGT STAYS AROUND 5. ECB FAULTS NO FLAME AND INLET DOOR. MEMORY ERASED ON ECB AND RESTART OF APU ATTEMPTED WITH SAME RESULT. DURING BOTH START ATTEMPTS, SMELLED STRONG ELECTRICAL BURNING FUMES COMING FROM E&E AREA. UNABLE TO PINPOINT ISSUE CAUSING BURNING SMELL. AMM: 24-37-00-0AMM: 24-35-11-04 AMM: 24-00-00-06 REF TSI 24-32/3860, 1) VERIFIED OVERHEAD GAUGES, ECAM DC VOLTS AND DC AMPS OK FOR THE ESS T/R. 2) INSPECTED 2PC AND 3PC WITH NO VISUAL DEFECTS NOTED. 3) OPENED 106VU PANEL, INSPECTED, NO DEFECTS NOTED. 4) OPENED 101VU PANEAL AND INSPECTED COMPONENTS WITH NO DEFECTS NOTED.5) REF WRI #49-40/3862, R/R'D APU STARTER AMM: 49-00-00-5 REF MTSI 24-32/3860 FOR FUNCTION CHECK. AMM: 24-32-11-04 R/R'D ESSENTIAL T/R AND CONFIRMED BURNED SMELL. OPS CHECKS GOOD. REFERENCE ABOVE. ESS BUS NOW POWERED BUT #3 BATTERY READS 24 VOLTS AND WILL NOT CHARGE. (W/KIT) TRANSFORMER RECTIFIER MPN: F11QY3714 SRL OFF: 1.546R.. MPN: F11QY3714 ON SRL: 2736