What was found
CREW REPORTED, ON FINAL APPROACH, A SMALL PUFF OF SMOKE CAME FROM THE NAV/COM PANEL. CREW ACCOMPLISHED SMOKE IN COCKPIT CHECKLIST, SMOKE QUICKLY SUBSIDED AND NO FURTHER SIGNS OF THE PROBLEM EXISTED. ADVISED THE TOWER, AND LANDED WITHOUT INCIDENT. MX INSPECTED ACFT, FOUND AUTO PILOT COMPUTER HAD DISTINCTIVE BURNED ODOR. AUTO PILOT COMPUTER CIRCUIT BREAKER WAS PULLED AND COLLARED, AUTOPILOT WAS PLACED ON MEL (22-1-1). AFTER ISOLATING AUTOPILOT SYSEM, NO OTHER SOURCES OF ODOR COULD BE IDENTIFIED. ACFT RELEASED BACK TO SERVICE. AUTO PILOT COMPUTER WAS LATER R & R AND MEL WAS CLEARED.