What was found
ON FLIGHT 3404 THE CREW REPORTED THAT UPON REACHING 15600 FEET ON DEPARTURE THE CABIN ALTITUDE BEGAIN TO CLIMB IN THE AMBER THEN RED ON EICAS. THE CREW DECLARED AN EMERGENCY AND BEGAIN A DESCENT AND COMPLIED WITH AOM VOL 1 PROCDURES. THE AIRCRAFT LANDED WITHOUT INCIDENT RETURNING TO DFW. THE AIRCRAFT WAS REMOVED FROM SERVICE. FOUND FAULTY DIGITAL CONTROLLER. REMOVED AND REPLACED DIGITAL CONTROLLER IAW EMB-145 AMM 21-31-01. THE OPERATIONAL CHECK WAS GOOD IAW MM 21-31-00. NO FURTHER DEFECTS NOTED AT THIS TIME. THE AIRCRAFT WAS RETURNED TO SERVICE.