What was found
APPROXIMATELY 6 HOURS INTO FLIGHT HAD STRONG ODOR OF ELECTRICAL COMPONENTS OVER HEATING/BURNING. ALSO, HAD VISIBLE SMOKE HAZE. RAN SMOKE SOURCE AND ELECTRICAL FIRE CHECKLIST. CREW USED OXYGEN ODOR DISSIPATED AFTER 20 TO 30 MINUTES. FOUND WING ANTI-ICE CONTROL CARD AND RELAY WITH EVIDENCE OF OVERHEAT/BURNING. REPLACED RELAY AND CONTROL CARD OPERATIONAL CHECK NORMAL PER M/M 36-11-00 AND 24-00-00. ALSO, REPLACED A1, A8, A10, A13, AND A17 MASTER DIMMER CONTROL CARDS DUE TO SIGNS OF OVERHEATING PER M/M 33-12-00.