What was found
IAH - FLT 1934 - ON CLIMB-OUT FROM IAH, PASSING THROUGH FL180 EN ROUTE TO PHL, FLIGHT ATTENDANT ADVISED CREW OF A BURNING ODOR IN THE CABIN. FLIGHT RETURNED TO FIELD AT IAH AND LANDED WITHOUT FURTHER INCIDENT. AN EMERGENCY WAS DECLARED. MAINTENANCE FOUND THE FORWARD RIGHT WINDOW HEAT CONTROLLER NOT FUNCTIONING. A TRANSFORMER SMELL WAS BEING EMITTED FROM THE NR 4 CONTROL BOX. REMOVED AND REPLACED THE NR 4 FORWARD RIGHT WINDOW HEAT CONTROLLER. OPS CHECK GOOD. CLEARED ODOR/SMOKE FROM CABIN. AIRCRAFT OK FOR SERVICE. (M)