What was found
DURING FLIGHT 3500/3556/3542/3477, RT SCREEN HIGH TEMP LIGHT ON AND THE NR 2 ADC FAILED. AIR RETURN TO DTW. MAINTENANCE VERIFIED WIRES INSTALLED CORRECT. CHECKED RES AT ELEMENTS & THERM. CHECKED OUTPUT VOLT FROM NET FILTERS. CHECKED SYS WIRING. ALL CHECKS GOOD. REPLACED RELAYS 2HL14 & 2HL15, BOARD CAPACITOR 2HL23, & PCB 2HL18. PERFORMED SCREEN HEAT OPS TEST IN BOTH GROUND & AIR MODE. CHECKS GOOD. REF MM409 066888.