What was found
(CAN) ACFT OPERATING, RETURN AFTER THE F/A`S SMELLED BURNING PLASTIC AROUND ROW 3 AFTER REACHING TOP OF CLIMB. PASSENGERS ALSO REPORTED ODOR IN ROW 3 AND MIDDLE OF CABIN. CREW RAN SMOKE QRC AND CHECKLIST, DECLARED AN EMERGENCY AND DID AN AIR TURNBACK. MAINTENANCE INVESTIGATED THE REPORT FROM THE FLIGHT CREW OF BURNING PLASTIC/RUBBER ODOR, ISOLATED AROUND ROW 3 ABC. CREW ALSO REPORTED LTV SCREENS AT ROW 2ABC WENT OUT AROUND THE TIME BURNING ODOR WAS NOTICED. FIM 21-00, TASK 806 CARRIED OUT, LIGHT BALLASTS AND CEILING PANELS INSPECTED FOR EVIDENCE OF BURNED RESIDUE, NO FAULTS FOUND. CARRIED OUT LTV INTEGRITY CHECK AND DIDN`T FIND ANY SIGNS OF BURNING AT ROWS 2, 3, 4 LT, REPLACED SEB`S AT ROWS 3 LT,4 LT AND THE LTV SYSTEM OPS TESTED SERVICEABLE IAW LTV AMM 44-20-28.