What was found
DURING TAKEOFF FROM ATL-CHA, WHILE IN TRANSITION TO CLIMB THE CREW RECEIVED A STAB TRIM AND MACH TRIM AMBER CAUTION MESSAGE. QRH PROCEDURES WERE COMPLIED WITH, BUT THE TRIM WOULD NT RE-ENGAGE. AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO ATL, LANDING SAFELY. MAINTENANCE REMOVED AND REPLACED THE CO-PILOTS PITCH TRIM DISCONNECT SWITCH. OPS CHECKS GOOD. AIRCRAFT OK FOR SERVICE. (M)