A20B-8100-0721 Fanuc PCB Board A20B81000721 A2OB-8IOO-O72I

FANUC A20B-8100-0721 Power Supply PCB

Overview

The A20B-8100-0721 is a FANUC power supply PCB in the A20B-8100 family. It is described as a power supply PCB and also as a DC-DC converter module, with listings linking it to compatible 16i, 18i, and 21i control systems.

One listing further describes it as a bolt-on DC-DC converter attaching to the main board, which places it clearly in the control power section rather than in the display, I/O, or servo-amplifier section.

In practical maintenance work, this type of board is not treated as a generic PCB. A control power board must match the installed power architecture of the CNC, because it supports stable internal supply distribution for the controller hardware already built around it.

Using the same model helps preserve the existing power-board layout and keeps the replacement aligned with the original control family.

Technical Data

Applications

This board is suited to installed FANUC CNC controls that already use the A20B-8100-0721 power-board structure, especially in 16i, 18i, and 21i hardware environments.

It is particularly relevant in controller repair, board-level refurbishment, and exchange-based spare support where the original internal power layout must remain unchanged.

Replacement Guidance

Before ordering, confirm the installed part number, verify that the machine uses the same power supply PCB / DC-DC converter position, and check that the control family matches the 16i / 18i / 21i application context.

Because this board is tied to the control’s internal power structure, exact model continuity is one of the most important replacement checks.

FAQ

Q1: What kind of board is A20B-8100-0721?

It is a FANUC power supply PCB. Listings also describe it as a DC-DC converter module, which means it belongs to the controller’s internal power-conversion section rather than to the display, memory, or signal-I/O side of the system.

That role is important because a power board directly supports the operating stability of the installed CNC control.

Q2: Why is the DC-DC converter description important?

Because that description identifies the board by function, not just by part number. A board described as a DC-DC converter module is part of the machine’s internal power-conditioning path, so it should be replaced with the same functionally matched model.

That is especially important in CNC hardware where power distribution has to remain consistent with the original design.

Q3: Which FANUC controls is this board commonly associated with?

The model is associated with FANUC 16i, 18i, and 21i controls, and one listing identifies it more specifically as a model A bolt-on DC-DC converter attached to the main board in those control families.

That gives it a clear installed-base context for service and replacement work.

Q4: Is this a main board or a support board?

It is a support board in the power section, not the main CPU board. Its job is tied to internal power handling and conversion for the control system.

That distinction matters because a power-support board must be chosen by exact installed role, not by appearance alone.

Q5: What should be checked before ordering?

Check the installed board code, confirm the control family is 16i, 18i, or 21i, and verify that the original board is A20B-8100-0721 in the power-supply / DC-DC converter position.

If the machine has already been repaired in the past, it is also worth confirming the current installed board label directly on the hardware before purchase.