The FANUC A20B-3900-0141 is a combined CNC memory module providing 8MB FROM and 1MB SRAM. The FROM section supports system-software storage, while the SRAM section provides writable memory for data required by the applicable controller configuration.

FANUC documentation identifies this module in the Power Mate i-D and Power Mate i-H hardware family. Other compatible FANUC control applications may exist, but the controller, CPU card, software and PCB revision must be verified before replacement.

A20B-3900-0141 Product Information

Combined FROM and SRAM Functions

The module combines two different memory functions on one assembly. Its FROM section stores non-volatile control-system software, while the SRAM section supports writable control and machine data. A replacement module may therefore require both the correct system software and restoration of the original SRAM backup.

Model and Capacity Differences

A20B-3900-0141 is an 8MB FROM and 1MB SRAM module. It should not be confused with A20B-3900-0041, which is an 8MB DRAM module, or A20B-3900-0140, which provides 12MB FROM and 1MB SRAM. Similar physical dimensions do not confirm interchangeability.

Replacement and Data Protection

Confirm the complete part number, PCB revision, controller model, CPU card, memory requirements and installed software. Back up parameters, programs, PMC data, offsets and other available machine information before removal. Never touch the module pins or edge contacts directly, and use proper anti-static protection during installation.

REACO CNC checks the model label, PCB, memory devices, solder joints, contacts and system recognition as applicable. Software loading and backup restoration should be performed by qualified FANUC personnel using the correct machine files.

Related resources: FANUC CNC and robot parts and FANUC memory module and PCB repair services.