What was found
DURING TAXI IN L FMC WENT BLACK (AT SAME TIME AS SOUND AND SMOKE APPEARED AFTER AC WAS BLOCKED IN MAINTENANCE GROUNDED AC AND ACCOMPLISHED FMC INTERFACE CHECK AND WIRING CHECK MORMAL LH FMC INOP .CONTACTED ENG. RECEIVED REA 3400-65418-00 TO PULL AND COLLAR BREAKER C609. SWAPPED LH TO RH AFTER POWER UP AND VERIFY NO SMOKE THEY DEFERRED THE RH FOR DEPARTURE IAW MEL 34-61-1-1A. AND RETURES TO SERVICE .AFTER ARIVAL IN CVG . RELACED RH FMC CDU OPS CHECK GOOD IAW AMM 34-61-02 PLACARDS REMOVED THE CLEARS DI 52779.