What was found
IMMEDIATELY AFTER TAKEOFF, POWER SET, WE GOT THE RED DITCH LIGHT THE YELLOW AUTO PRESS FAULT LIGHT AND THE FOLLOWING EICAS MESSAGES CABIN ALT HIGH AUTO PRESS R FADEC MINOR PRESS MONITOR ADDITIONALLY THE CABIN OXYGEN MASK DEPLOYED. INTERAGATED MDC AND FOUND CPC CHANNEL A AND B FAILURE. REMOVED FAULTY CPC AND INSTALLED A REPAIRED UNIT. PERFORMED OPS TEST WITH NO FAULTS NOTED IAW MM 21-30-00 AND 21-30-07 (VERIFY MODE, MANUAL MODE TEST, AUTO PRESSURE TAKEOFF MODE).