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| Place of Origin | JAPAN |
| Brand Name | FANUC |
| Certification | CE ROHS |
| Model Number | A20B-3900-0280 |
The FANUC A20B-3900-0280 is a memory module in the A20B-3900 family. It is listed with 128MB FROM and 1MB SRAM, which places it in the control-memory category rather than in the display, power-supply, or amplifier-control categories.
In FANUC systems, a module like this is used where stored control software and retained controller data need a defined memory board rather than a generic plug-in card.
Maintenance-manual excerpts also distinguish this model as a FROM/SRAM module B1 in the newer A20B-3900-028x specification family.
That makes it a board worth handling carefully during replacement, especially in systems where memory configuration, version matching, and stored data integrity matter as much as physical fit.
For product-page purposes, the clearest way to position A20B-3900-0280 is as a high-capacity FANUC memory module for repair, replacement, and controller memory restoration.
It is the kind of part buyers look for when the original control hardware is still worth maintaining and the fastest solution is to replace the exact memory module rather than alter the wider control platform.
| Item | Specification |
|---|---|
| Part Number | A20B-3900-0280 |
| Brand | FANUC |
| Product Type | Memory Module |
| Memory Type | FROM / SRAM |
| FROM Capacity | 128MB |
| SRAM Capacity | 1MB |
| Module Group | A20B-3900 series |
| Manual Classification | FROM/SRAM Module B1 |
| Typical Use | Controller memory replacement |
The A20B-3900-0280 is most appropriate for controller memory replacement, software storage support, and control restoration projects where a FANUC system requires a 128MB FROM / 1MB SRAM module.
Because it belongs to the FROM/SRAM memory class, it fits applications where preserving the original controller memory structure is more important than changing the broader hardware platform.
In maintenance environments, this module is especially useful for board-level memory repair, backup-oriented replacement work, and spares inventory for installed FANUC controls that still rely on the A20B-3900 memory family.
It is a practical choice when the machine remains productive and the most efficient repair path is to replace the exact memory module rather than rework the entire control.
Q1: What kind of board is A20B-3900-0280?
It is a 128MB FROM / 1MB SRAM memory module. That means it belongs to the controller-memory section and is intended for storage and retained-data functions rather than for motion control or operator-panel tasks.
Q2: Why does the FROM/SRAM combination matter?
Because the module combines a larger nonvolatile storage area with a smaller SRAM area used for retained control data. In real maintenance work, that distinction matters when backing up, restoring, or replacing controller memory hardware.
Q3: What should technicians do before replacing this module?
They should verify the exact part number, confirm the controller’s memory configuration, and protect any required backup data before removal. Since this module sits in the stored-memory path, a hardware swap without preparation can turn a board replacement into a data-recovery problem.
Q4: Is this module interchangeable with every A20B-3900 board?
No. The A20B-3900 family includes multiple FROM/SRAM variants with different capacities and specifications. Matching the exact model is important because memory size and module version can change the way the controller expects to read or retain data.
Q5: Where does this part make the most sense in service work?
It fits best in controller memory repair, replacement stock, and long-life FANUC system support where the original control hardware remains valuable and needs the correct memory module to stay in service.
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