What was found
DURING CRUISE FLT AT 340 VTK FLAG ON CAPT,S SIDE BOTH FMC DISPLAYS BLANKED AND THEN WENT TO MENU ON DISPLAYS VTK WENT AWAY AND BOTH FMC'S OPERATED NORMALLY AFTER. GROUNDED - YES. DFCS BITE SHOWS FMC #1 REBOOTED AT FL 340 ON LEG 3 AND AGAIN ON LEG 2 AT FL 350. MDS FAULTS CODE 34-69001 ON THE SAME LEGS. REVERSED MEL CONFIG. RESET FMC 1 & 2 REF B737-9 IFIM 34-61-00-810-836. OPS TEST GOOD. C/W FMS LRU REPLACEMENT TEST. OPS CHECK GOOD.