What was found
AT FLIGHT LEVEL 250, REDUCED POWER FOR DESCENT, CABIN ALTITUDE STARTED TO CLIMB AT 1500 FEET PER MINUTE. STANDBY MODE WAS SELECTED AND TOTALLY LOST PRESSURIZATION, OXYGEN MASK DROP. REMOVED AND REPLACED CABIN PRESSURE CONTROLLER. PERFORMED PRESSURE DECAY CHECK. RE-PACKED OXYGEN MASK. OPS CHECKS AND LEAK CHECKS NORMAL IAW MM 21-31-21, 21-31-0, 5-51-91, AND 34-11-0.