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| Place of Origin | JAPAN |
| Brand Name | FANUC |
| Certification | CE ROHS |
| Model Number | A20B-8100-0137 |
If your project or service job calls for a 21i-A LCD mounted main PCB with PMC-SA1, the FANUC A20B-8100-0137 is the model tied to that configuration in public parts listings.
FANUC documentation for the same control family identifies PMC-SA1 as the lighter PMC option, with a basic instruction speed of 5 μs/step and a maximum ladder size of 5,000 steps.
That positioning gives this board a distinct maintenance role.
It is suited to applications where the machine already uses the original 21i-A LCD mounted structure and where preserving the established control format is more practical than altering the hardware platform.
From a buyer’s point of view, the board is valuable because it supports continuity: same family, same mounted concept, and the PMC type expected by the original setup.
| Parameter | Data |
|---|---|
| Part Number | A20B-8100-0137 |
| Manufacturer | FANUC |
| Board Type | Main PCB |
| Installation Style | LCD mounted |
| Associated Control Family | 21i-A |
| PMC Version | PMC-SA1 |
| Basic Instruction Speed | 5 μs/step |
| Maximum Ladder Steps | 5,000 |
| Typical Application | CNC repair and replacement |
Compared with the SA5 variant, this board is tied to the PMC-SA1 configuration, which is the more compact option in the same FANUC family documentation.
That distinction is useful when identifying the correct replacement board for a machine that must retain its original control logic environment instead of being reworked around a different PMC arrangement.
Q1: What is the main role of the A20B-8100-0137?
The A20B-8100-0137 is an LCD mounted main PCB associated with the PMC-SA1 configuration. In industrial use, that places it in the main control layer rather than in a simple support role.
It is typically selected when the machine depends on its original 21i-A mounted architecture and needs a like-for-like replacement.
Q2: How is PMC-SA1 different from PMC-SA5 in practical terms?
Published FANUC data shows PMC-SA1 with a slower basic instruction speed and a smaller ladder capacity than PMC-SA5.
In practical terms, that means the board belongs to a different PMC configuration, so it should not be treated as interchangeable with an SA5 version unless the full system design supports that change.
Q3: Why does an LCD mounted main PCB need careful identification?
Because boards in this class are tied to both the control family and the physical integration format.
The LCD-mounted design affects how the board fits within the control assembly, while the PMC type affects logic-side behavior. Exact identification helps avoid mismatch at both levels.
Q4: What service checks should be made before replacing this board?
Technicians should confirm the complete part number, inspect the LCD-mounted assembly, verify surrounding power and connector condition, and check whether there are related faults in cables or option boards.
With main-PCB replacements, a structured diagnosis is always better than swapping parts by guesswork.
Q5: Why is this board relevant for long-life CNC equipment?
Many 21i-A based machines remain in productive use long after initial installation.
For those machines, keeping the correct main PCB available supports practical maintenance, shortens downtime, and avoids unnecessary control migration when the original platform is still viable.
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