As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
A BURNING ODOR BEGAN COMING FROM THE PASSENGER SERVICE UNIT AT R/H SIDE, ROW 19 WHILE ON APPROACH TO IAH. THE AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND A CONTROL CIRCUIT CARD IN PSU HAD SHORTED. THE PSU WAS REMOVED AND REPLACED IAW MM 25-23-61. OPERATIONAL CHECKS WERE GOOD.