As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING SHORT FINAL APPROACH, SMOKE WAS DETECTED COMING OUT OF THE NR1 NAV CONTROL HEAD. THE NR1 NAV CB'S WERE PULLED, THE SMOKE STOPPED AND AC LANDED WITHOUT FURTHER INCIDENT. MAINT REMOVED AND REPLACED CONTROL HEAD AND CLEARED DISCREPANCY. SUBSEQUENT TEARDOWN AT REPAIR VENDOR SHOWED BURNED COMPONENTS ON POWER SUPPLY CARD. NO PRIOR HISTORY OF THIS PROBLEM ON COMPANY FLEET.