1 PC Used Fanuc A20B-2001-0930 PCB Board A20B20010930 A2OB-2OO1-O93O

FANUC A20B-2001-0930 | Alpha SVM1 Type-A Servo Drive Control PCB — A06B-6079 Single-Axis / 12–80A / LCD Alarm Display

Top Card of the Alpha SVM1 — Control Intelligence for One Axis

The A20B-2001-0930 is the Type-A control PCB — the top (front-facing) card — in FANUC's A06B-6079 series single-axis Alpha servo amplifier modules. It is the intelligence layer of the SVM1 module: it receives motion commands from the CNC via the Type-A PWM interface, processes the Alpha servo motor's encoder feedback, runs the servo control loop, and drives the power transistors in the wiring board below it.

One A20B-2001-0930 controls one axis. This is the single-axis equivalent of the A20B-2001-0940 (which controls three axes in an SVM3 three-axis module). Each drives its respective axis count independently, with the control PCB as the common functional element across the SVM1 module range from 12A to 80A.

The front-mounted LCD display shows the status and alarm codes for the axis — a two-digit display that indicates operating state during normal running and an alarm number when a fault occurs. This display is the first diagnostic tool when an Alpha servo axis faults: the alarm code on the LCD identifies whether the fault is in the power stage, the motor, the encoder, or the communication interface between the CNC and the drive.

Key Specifications

Type-A PWM — The Interface Generation Before FSSB

The A06B-6079 Alpha SVM uses the Type-A interface — PWM (pulse-width modulation) signals carried on cable between the CNC servo interface board and the drive module. The A20B-2001-0930 receives these PWM current commands from the CNC, processes them through the servo loop, and drives the output transistors accordingly. It also returns alarm and VRDY (velocity ready) signals back to the CNC through the same cable interface.

This Type-A interface places the A06B-6079 SVM generation before the FSSB optical fibre interface used in the A06B-6096 and later Alpha i series. The two interface types are incompatible — a Type-A drive cannot be substituted with an FSSB drive without changing the CNC's servo interface hardware. Confirm the interface type from the installed drive module before specifying a replacement.

FAQ

Q1: The Alpha SVM1 axis shows an alarm. How is the A20B-2001-0930 identified as the fault source?

Check the LCD display on the module face — the two-digit code identifies the alarm category. Alarms pointing to servo communication (VRDY fault, communication error) or control card initialisation failure on a single axis point to the A20B-2001-0930 control PCB. Power stage alarms (overcurrent, IPM fault, DC bus fault) point to the wiring/power board below it. Confirm the axis motors and cables are undamaged before concluding the control card has failed.

Q2: What is the difference between A20B-2001-0930 and A20B-2001-0932?

Both are Alpha SVM1 Type-A single-axis control PCBs in the A06B-6079 series. The -0930 covers the standard SVM1 current range (12A to 80A). The -0932 is associated with the SVM1-130 module (130A class). They are not interchangeable — the control PCB must match the power stage it commands. Confirm the exact suffix from the installed module's wiring board label.

Q3: Can the A20B-2001-0930 be tested in isolation without the full SVM1 module?

No. Functional verification requires running the complete SVM1 module with a connected Alpha servo motor under load — conditions that cannot be replicated on a bench without the full drive assembly. Swap testing with a confirmed-good A20B-2001-0930 in the complete module is the definitive diagnostic and verification method.

Q4: Are there configuration switches on the A20B-2001-0930 that must be set correctly?

The Type-A control PCB carries configuration switches for axis parameters and interface settings. Before removing the original card, photograph or record all switch positions. The replacement must be configured identically. Incorrect switch settings produce VRDY failures, wrong alarm codes, or servo behaviour that does not match CNC expectations.

Q5: Where is the A20B-2001-0930 sourced?

Through the FANUC Alpha servo drive aftermarket — Alpha SVM module specialists, FANUC CNC drive repair centres, and tested surplus suppliers. Note that many aftermarket suppliers only supply the A20B-2001-0930 as part of the complete tested A06B-6079 SVM1 module rather than as a bare card, because isolated testing of the control card without the full module is not feasible.