The FANUC A20B-2003-0271 is a one-slot control-unit back panel PCB for selected FANUC Series 0i Mate-B CNC systems. Installed at the rear of the control-unit cabinet, it provides the internal backplane connection used by the main CPU assembly and associated control-unit hardware.

FANUC documentation lists A20B-2003-0271 as the one-slot back panel and identifies A02B-0301-B801 as a documented 0i Mate-B one-slot basic unit. This board should not be classified as a standalone power supply or distributed I/O module.

A20B-2003-0271 Product Information

One-Slot Backplane Function

The A20B-2003-0271 forms the rear electrical and mechanical interface inside the one-slot CNC control unit. It supports secure board seating and routes the internal bus and supply connections between the installed control hardware. The assembly also includes the connection used by the control-unit fan.

Compatibility and Replacement Checks

Confirm A20B-2003-0271 on the original PCB together with the complete A02B basic-unit number, cabinet type, slot count, main CPU board and connector arrangement. Do not substitute A20B-2003-0490 solely because both parts are FANUC back panels; the latter is documented as a two-slot configuration.

Testing and Installation Notes

REACO CNC checks the label, PCB condition, connector pins, fan connection, board engagement, internal continuity and controller startup under an applicable test setup. Back up parameters, programs and other SRAM data before replacement. Power must be isolated, and the main CPU and installed boards should be removed and reinstalled by qualified personnel using ESD protection.

Related resources: FANUC PCB boards, FANUC CNC controls and FANUC CNC repair services.