What was found
PASSING FL 180 DURING CLIMB, THE FIRST OFFICER LOST ALL CONTROL OF HIS BARO ALTIMETRY, ALT DISPLAYED BOTH EAD'S, ALT WINDOW ON AFS PANEL WENT BLANK, NO CONTROL WITH ALTITUDE KNOB. AIRSPEED HDG ALSO BLANKED WITH NO CONTROL, AUTO THROTTLES LOCKED. AIR TURN BACK. TROUBLESHOT IAW FIM 22-00-00-810-837, BOTH FCC'S HAVE CURRENT FAULTS ADC 1 AND ADC 2 BARO COR ALT LNV FLO BARO COR ALT INV FLO BARO KNOB INOPERATIVE. REMOVED AND REPLACED ADC 2 IAW AMM 34-16-01 ADC OPS TESTED OK IAW AMM 34-16-01, BARO KNOB ON FIRST OFFICER`S SIDE RETURNED TO NORMAL OPERATION. PERFORM AFS CAT3 B TEST ON FCC 1 AND FCC.