1 PC Used Fanuc A20B-2101-0050 Control BoardIn Good Condition A20B21000050 A2OB-21O1-OO5O

A20B-2101-0050 | FANUC Beta-i SVM1 Control PCB — SVM1-4i / SVM1-20i / SVM1-40i / A06B-6130-H001/H002/H003 / FSSB / Dynamic Brake

Beta-i SVM1 — Economy Single-Axis Servo Drive

The FANUC Beta-i (βi) series occupies the economy tier of FANUC's servo drive product range. Where the Alpha-i series targets high-performance applications demanding maximum servo stiffness and contouring accuracy, the Beta-i serves machine tools where reliable servo performance at a practical cost is the priority.

The Beta-i SVM1 (Single-axis servo module, A06B-6130 series) provides one servo axis per module:

The A20B-2101-0050 is the common control PCB for the 4i, 20i, and 40i variants. The 80i requires a separate control PCB (A20B-2101-0051).

Key Specifications

Dynamic Brake — Controlled Deceleration on E-Stop

The A20B-2101-0050 control PCB enables the SVM1's dynamic brake function. This function activates automatically when the drive is disabled — on E-stop, alarm trip, or power loss:

How it works: When the drive disables its output, the control PCB commands a circuit that connects a resistor across the servo motor's phase windings. The motor, still spinning due to inertia, becomes a generator — driving current through the brake resistor. This generates a braking torque that decelerates the axis significantly faster than free-coasting.

Why it matters: An uncontrolled coasting axis after E-stop can damage tools, fixtures, or workpieces. Dynamic brake provides a predictable, faster stop — protecting both the machine and the operator.

Application Scenarios

Beta-i SVM1-20i control PCB fault: A compact CNC machining centre's Beta-i SVM1-20i (A06B-6130-H002) develops FSSB communication alarms. The power board is confirmed intact. Replacing the A20B-2101-0050 control PCB restores FSSB communication.

Economy CNC axis servo board replacement: A CNC machine uses three separate SVM1-20i drives for its three axes. All three use the same A20B-2101-0050 control PCB — stocking one spare covers all three drives regardless of axis.

FAQ

Q1: Does one A20B-2101-0050 cover SVM1-4i, 20i, and 40i — all three current ratings?

Yes. The FANUC Beta-i Series Descriptions Manual (B-65322EN/02) confirms A20B-2101-0050 as the control PCB for all three: SVM1-4i (H001), SVM1-20i (H002), and SVM1-40i (H003). The power board changes with each current rating, but the control PCB is common across the three variants.

Q2: Can A20B-2101-0050 replace A20B-2101-0051 (used in SVM1-80i and SVM1-40HVi)?

No. The A20B-2101-0051 serves the higher-current SVM1-80i and the high-voltage SVM1-40HVi. These variants require different current feedback scaling and gate drive interface hardware. Fitting A20B-2101-0050 in an SVM1-80i produces incorrect current regulation. Always match the control PCB to the specific drive model.

Q3: What power boards are paired with A20B-2101-0050 in each SVM1 variant?

From the FANUC Beta-i manual (B-65322EN/02):

• SVM1-4i and SVM1-20i (H001/H002): Power board A20B-2101-0091
• SVM1-40i (H003): Power board A16B-3200-0512

Both the control board and the power board must be functional for the drive to operate. Confirm both before replacing only one.

Q4: Does replacing A20B-2101-0050 require servo parameter re-entry?

No. Servo parameters (motor ID, encoder type, gain values) reside in the CNC's main parameter memory. After fitting the replacement A20B-2101-0050, the CNC re-establishes FSSB communication and applies existing parameters automatically. Verify normal servo response before returning to production.