What was found
WHILE EN ROUTE, THE ACFT EXPERIENCED SMOKE IN THE COCKPIT, APPROX 20 MILES FROM DESTINATION. THE CREW SHUTDOWN AVIONICS & DECLARED AN EMER. THE ACFT LANDED SAFELY & WAS MET BY FIRE DEPARTMENT. FIRE DEPARTMENT VERIFIED NO FIRE OR SMOKE EXISTS. TROUBLESHOOTING FOUND THE COPILOT'S OR RT PRIMARY FLIGHT DISPLAY, PFD WAS CAUSE OF SMOKE. REMOVED FAULTY PFD & INSTALLED AN OVERHAULED UNIT OF LIKE PN WHICH OPERATIONS CHECKED SATISFACTORILY. FURTHER INVESTIGATION FOUND NO OTHER ISSUES RELATING TO SMOKE INCIDENT. THE ACFT WAS RETURNED TO SERVICE & THE FAULTY UNIT WAS SENT FOR REPAIR. DISPLAY UNITS ARE ON CONDITION ITEMS & MAY NEED AN OVERHAUL LIMITATION TO HELP PREVENT FUTURE INTERNAL COMPONENT FAILURES, WHICH RESULT IN SMOKE IN COCKPIT.