What was found
CABIN ALT AUTO 1 STATUS MESSAGE RECEIVED CLIMBING OUT OF 15,000 FEET, ONCE LEVELED AT FL200 FOR APPROXIMATELY 5 MIN, RECEIVED A MASTER WARNING CABIN ALTITUDE , DECLARED AN EMERGENCY, FOLLOWED QRC AND QRH PROCEDURES, MADE DESCENT TO 8,000 FEET.LANDED AT KSHV WITH NO FURTHER ISSUES. EMERGENCY DECLARED. BITE CHECK CABIN ALTITUDE CONTROLLER NR 1, ALL COMPONENTS SHOW FAIL SUSPECT BAD CONTROLLER. ALSO PERFORMED BITE CHECK ON NR 2 CONTROLLER SHOWS AC MOTOR FAIL IAW AMM 21-31-00-5. REMOVED AND REPLACED AUTOMATIC CABIN PRESSURE CONTROLLER NR 1 IAW B757 AMM 21-31-02-4 OPS CHECK GOOD.