What was found
AFTER TAKEOFF, THE CREW SMELLED ELECTRICAL SMOKE. THE CAPTAINS EADI SCREEN WENT BLANK AND THE SMOKE STOPPED WHEN THE LEFT AVIONICS WAS SWITCHED OFF. THE AVIONICS SMOKE LIGHT ON THE ANNUNCIATOR PANEL DID NOT ILLUMINATE. THE AIRCRAFT RETURNED TO FIELD WITHOUT INCIDENT. UPON INVESTIGATION MAINTENANCE FOUND THE LEFT DIGITAL PROCESSING UNIT, DPU FAILED. REPLACED LEFT DPU, EFIS SCREEN AND THE AVIONICS RACK FILTER. AIRCRAFT RELEASED FOR SERVICE.