What was found
SEA - ATB SMOKE IN FLIGHT DECK THROUGH 1000 FT. COMING FROM G4 AND G5 AREA, BEHIND F/O AREA. TROUBLESHOT NR 2 ENG GCU. INSPECTED AREA NEAR P-6 C/B PANELS, EE COMPARTMENT, AND NR 2 ENGINE GENERATOR. REPLACED NR 2 GCU. ENGINE RUN, OPS CHECK NORMAL. GCU RECEIVED UNSERVICEABLE. INSP SHOWED INTERNAL PWR SUPPLY CIRCUIT OVERHEATED AND TRANSFORMER T901 AND DIODE CR909 HAD OVERHEATED AND BURNED. TRANSFORMER AND DIODES TO BE REPLACED. UNIT REQUIRES COMPLETE CLEANING TO REMOVE BURNED COMPONENTS AND RESIDUE. (K)