What was found
ON FLIGHT 4524 THE CREW REPORTED A STRONG SMOKE ODOR COMING FROM A PASSENGER SERVICE UNIT AT SEAT 8A IN THE CABIN. THE CAPTAIN DECLARED AN EMERGENCY AND THE AIRCRAFT LANDED WITHOUT INCIDENT AT BOS. THE AIRCRAFT WAS REMOVED FROM SERVICE. FOUND BURNING ODOR FROM BALLAST AT SEATS 7A AND 8A. REMOVED AND REPLACED CEILING BALLASTS IAW EMB AMM 33-21-05. THE OPERATIONAL CHECK WAS GOOD, NO FURTHER SMOKE SMELL NOTED. RE-SECURED PASSENGER SERVICE UNIT LATCH AT SEAT 8A AS REQUIRED. THE AIRCRAFT WAS RETURNED TO SERVICE.