FANUC A20B-3900-0182

32MB FROM / 256KB SRAM Module for FANUC Control Memory Repair

Main Description

The FANUC A20B-3900-0182 is a FROM/SRAM memory module with 32MB FROM and 256KB SRAM. It belongs to the A20B-3900 family and is used in the control-memory section rather than in the amplifier, display, or operator interface area.

In real maintenance work, this kind of module is selected when the original control still has value and the correct memory hardware is needed to keep the system structure intact.

This model is also described with a 5V operating voltage, 5W power dissipation, CMOS/TTL signal levels, and an edge-connector board format.

Those details make it easier to position as a dedicated internal memory board rather than a generic replacement PCB.

For product-page purposes, the cleanest way to describe it is as a FANUC 32MB FROM / 256KB SRAM module for board-level replacement and controller memory restoration.

Parameter Table

Applications

The A20B-3900-0182 is best suited to control-memory replacement, board-level CNC repair, and restoration of FANUC systems that depend on the original A20B-3900 memory structure.

It is most useful where the control hardware is still serviceable but the memory module must be replaced with the same capacity profile to preserve compatibility.

It is also a practical fit for repair inventory, legacy machine support, and maintenance departments that handle internal memory-board failures.

Because its SRAM value is only 256KB, it should be treated as a specific configuration rather than as a general substitute for any 32MB A20B-3900 module.

Replacement Guide

Before replacing the A20B-3900-0182, confirm the exact module number and memory configuration already installed in the control. In the A20B-3900 family, similar-looking boards can still differ in SRAM size, and that difference matters in actual system fit.

For this reason, matching the full part number is safer than matching only the FROM size.

It is also good practice to check the control’s backup procedure before removal, inspect the edge connector and receiving socket, and verify that the memory fault is not being caused by the main board or a separate software issue.

After replacement, confirm stable startup and normal controller behavior before returning the machine to production.

FAQ

Q1: What kind of module is A20B-3900-0182?
It is a FANUC FROM/SRAM memory module with 32MB FROM and 256KB SRAM, used inside the controller memory structure.

Q2: Why is the 256KB SRAM value important?
Because SRAM size is part of the module’s identity. Even another 32MB FROM module in the same family can still be a different board if the SRAM configuration is not the same.

Q3: What electrical details are available for this module?
The published details include 5V operation, 5W power dissipation, CMOS/TTL signal levels, and an edge connector format.

Q4: Is this module mainly used in repair work?
Yes. The current market around this model is centered on replacement and service use, which makes it far more relevant to maintenance and restoration than to new-system development.

Q5: What should technicians verify before buying or replacing it?
They should confirm the exact part number, the installed memory configuration, the connector condition, and the control’s backup status. With memory modules, correct identification is just as important as the physical replacement itself.