What was found
(CAN) SMOKE IN COCKPIT IN FLIGHT WHILE EXITING AN INBOUND HOLD. AFTER INVESTIGATION, AN AFTER SMOKE DISSIPATED AN EICAS (ENGINE INDICATION AND CREW ALERT SYSTEM) MESSAGE APPEARED FOR A TRIPPED OFF LINEOF THE FORWARD ELECTRICAL SUPPLY FAN. REPLACED AIR COOLING FAN AND REPLACED ELECTRICAL/ELECTRONICS EQUIPMENT COOLING SYSTEM 9 INCH DIAMETER AIR CHECK VALVE THAT WAS FOUND BROKEN. FAN SYSTEM OPERATIONAL AND MESSAGE CLEARED.