Fanuc A20B-2000-0650 is 6-slot backplane PCB for large CNC’s. Belonging to the Fanuc series 16/18 model A, B, and C control systems. This board is inserted into the yellow plastic frame which holds each board in place to connect the control system together. The PSU is normally on the right hand side of the control with the MAIN or CPU being next from the right. Then its a mixture of boards dependent on what type of CNC machine tool.