What was found
CREW REPORTED ON TAXI OUT BOTH EICAS SCREENS BLANK FOLLOWED BY COMPACT MODE. UPPER EICAS BLANK THEN HOT ELECTRICAL SMOKE NOTED. CREW ELECTED A BLOCK RETURN FOR FAULT ISOLATION AND CORRECTIVE ACTIONS. AIRCRAFT GROUNDED FOR MAINTENANCE. GENERAL VISUAL INSPECTION VERIFIED UPPER DISPLAY UNIT HAD DISTORTED COLOR AND INDICATION. INTEGRITY AND SECURITY OF EQUIPMENT COOLING SOURCE TO DISPLAY UNIT GOOD. EHSI & EICAS INDICATOR ASSEMBLY REMOVED AND REPLACED. LEFT AND RIGHT EICAS COMPUTERS OPERATIONAL CHECKS GOOD PER BOEING 767-300 AIRCRAFT MAINTENANCE MANUAL 31-41-01 AND 31-41-02. NO ADDITIONAL FAULTS NOTED, AIRCRAFT RELEASED TO SERVICE.