What was found
(CAN) PRIOR TO PASS BOARDING WHILE FLIGHT ATTENDANTS PREPARED THE CABIN FOR FLIGHT SMOKE AND ARCING WAS NOTICED COMING FROM THE REAR OF THE AIRCRAFT GALLEY COFFEE MAKER CB PANEL. ELECTRICAL POWER WAS REMOVER FROM THE AIRCRAFT GALLEY AND THE FIRE EXTINGUISHER FIRED INTO THE COMPARTMENT. NR 2 COFFEEMAKER CB AND ATTACH WIRES HAD BEEN SEVERELY OVERHEATED AND PART OF THE HOUSING AND WIRES WERE BURNED. CB AND WIRES REPLACED.