What was found
F/A REPORTED HEAVY ELECTRICAL BURNING SMELL FROM ROW NR 2-4 CAPTS SIDE AT APPROXIMATELY FL 290. RAN QRH FIRE/SMOKE/FUMES CHECK LIST. F/A REPORTED ELECTRICAL SMELL DIMINISHING, DECLARED EMERGENCY. HAD FIRE DEPT SCANNED INSIDE WITH THERMAL SCANNER AND HAD SMELL HOT SPOT. F/A PULLED PIN ON FIRE EXTINGUISHER, BUT DID NOT DISCHARGE EXTINGUISHER. REMOVED AND REPLACED PSU'S ON ROWS 2 ABC; 3 ABC AND 4 ABC, PER MM 25-23-31 AND MT 735-22-02 REP.