What was found
DIVERSON / DECLARED EMERGENCY. DURING CRUISE AT FL 230, CABIN ALTITUDE WARNING HORN SOUNDED, CREW DONNED 02 MASKS AND COMMENCED DESCENT, COMPLETED QRH CHECKLIST. NO OTHER PROBLEMS NOTED WITH AIRCRAFT (RAPID DEPRESSURIZATION). REMOVED AND REPLACED CABIN PRESSURE CONTROLLER, MAIN OUTFLOW VALVE, AND PRESSURE CONTROL PANEL PER MM.