What was found
CREW REPORTED- WHILE AT FL360 EN-ROUTE TO LAS, AUTOPILOT FAILED FOLLOWED BY MULTIPLE SYSTEM FAILURES EMBLEMATIC OF A DC BUS1 FAILURE EVEN THOUGH DC BUS 1 FAIL DID NOT APPEAR ON THE EICAS. SYSTEMS INCLUDED TRIM, PRESSURIZATION , HYDRAULICS, FLAPS, SPOILERS, ETC. ALSO INCLUDED ANTI-ICE, SPS, LG AIR/GND FAIL. CORR ACTION MX TROUBLESHOOTING WITH EMB MFR SME'S AS THIS IS A REPEAT ISSUE. AIRCRAFT STILL AOG UNTIL ISSUE FOUND.