A20B-3900-0227 Fanuc PCB Board A20B39000227 A2OB-39OO-O227
FANUC A20B-3900-0227
64MB FROM / 2MB SRAM R301A Module for FANUC Control Memory Support
Main Description
The FANUC A20B-3900-0227 is a 64MB FROM / 2MB SRAM R301A module from the A20B-3900 family. In practical terms, it belongs to the control-memory side of a FANUC system rather than the amplifier, display, or operator-panel section.
A module in this class is used where stored system data and retained controller memory need to remain consistent with the original hardware layout.
What makes the A20B-3900-0227 useful in service work is its balance of larger FROM capacity and dedicated SRAM space.
That combination makes it suitable for repairs where the machine still has value in production and the most effective solution is to replace the exact memory module instead of altering the wider control platform.
On a product page, it is best positioned as a memory module for restoration, replacement, and long-term support of installed FANUC controls.
Parameter Table
| Parameter | Value |
|---|---|
| Part Number | A20B-3900-0227 |
| Brand | FANUC |
| Product Type | Memory Module |
| Module Type | R301A Module |
| FROM Capacity | 64MB |
| SRAM Capacity | 2MB |
| Product Family | A20B-3900 series |
| Typical Use | Control memory replacement |
Applications
The A20B-3900-0227 is best suited to controller memory replacement, board-level control restoration, and spare-parts support for FANUC systems that still use the original A20B-3900 memory architecture.
It fits especially well in maintenance environments where the control hardware remains serviceable and the correct memory module is needed to preserve the existing configuration.
It is also a practical choice for repair stock, legacy CNC support, and service departments handling memory-board failures where the priority is to restore the original module structure rather than retrofit the whole control.
That application framing is an engineering use-case based on the module’s verified memory role and capacity.
FAQ
Q1: What kind of part is A20B-3900-0227?
It is a 64MB FROM / 2MB SRAM R301A memory module in the A20B-3900 series. That means it belongs to the control-memory section of the CNC rather than to motion control or panel interface hardware.
Q2: Why does the FROM and SRAM combination matter?
The two capacities indicate that the module is built to handle both stored memory and retained working memory in one board. In service terms, this matters because memory replacement is not just about physical fit; it is also about preserving the intended storage structure of the control.
Q3: Is this module mainly used in repair work?
Yes. Market listings around this part are centered on replacement and service supply, which makes it much more relevant to maintenance and restoration work than to new-machine design.
Q4: What should technicians check before replacement?
They should verify the exact part number, confirm the required memory capacity, and make sure the fault is really in the memory path rather than in the main board or a separate data issue. For memory modules, preparation and identification are usually just as important as the physical swap.
Q5: Why is exact model matching important for this module?
Because A20B-3900 modules exist in several different FROM/SRAM combinations.
Even modules from the same family can differ in memory size, so matching A20B-3900-0227 exactly is the safer way to preserve compatibility.
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