What was found
INSPECTION TYPE:N/A, RTR-NR 4 GEN PWR FAIL ILLUM, LWR CGO FIRE LIGHT ILLUM ALL PANEL LIGHTS WENT OUT, SMOKE OF UNKNOWN ORIGIN FILLED COCKPIT AND CABIN. SHUTDOWN 1, 2 AND 4 ENGINES. *S/D* T/S AND FOUND NR 4 VRG FAILED PREVENTING NR 1 BTR CLOSURE. REMOVED AND REPLACED NR 4 VRG PANEL. RAN ALL ENGINES. AC GEN SYST PREF CK AND OP CK NORMAL MM 24-20- 00. P/N ON/OFF 51508-000, S/N ON: 937ABC, OFF: 265ABC.