As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE ENTERED THE COCKPIT FROM BEHIND THE F/O'S SEAT WHILE ON FINAL APPROACH TO IAH. THE AIRCRAFT LANDED SAFELY AND TAXIED TO THE GATE UNDER ITS OWN POWER. THE SMOKE HAD CLEARED. MAINTENANCE FOUND THE FORWARD GALLEY WORK LIGHT BALLAST AT FAULT. THE BALLAST WAS REMOVED AND REPLACED. POWER WAS APPLIED TO THE SYSTEM AND OPERATION CHECKED GOOD WITH NO OTHER DEFECTS NOTED.