The FANUC A20B-3300-0120 is a four-axis high-speed axis control card for compatible FANUC CNC systems. Installed as a plug-in card in the control unit, it performs servo-axis control processing for as many as four controlled axes.

FANUC maintenance documentation identifies the board as a 4-axis card supporting 90A0 and 90A3 series servo software. It is commonly described in the replacement market as a high-speed servo control or FSSB card, but it is not a complete servo amplifier.

A20B-3300-0120 Product Information

Four-Axis High-Speed Servo Control

The card processes axis-control functions between the CNC and the matching servo system. Its four-axis capacity refers to the number of controlled axes supported by this card, not four independent power outputs. Motor power is supplied by separate servo amplifier modules within the machine's drive system.

Compatibility and Software Checks

Match the complete A20B-3300-0120 number, PCB revision, CNC model, motherboard, axis configuration and servo software. Do not substitute A20B-3300-0121, A17B-3300-0200 or A17B-3300-0201 solely because they belong to the same card family; they have different documented axis capacities.

Testing and Installation Notes

REACO CNC checks the label, card contacts, PCB condition, module recognition, startup status and axis-control operation on an applicable test system. Back up CNC parameters, servo parameters, programs, offsets and PMC data before replacement. Isolate power, observe ESD precautions and have qualified CNC personnel install the card.

Related resources: FANUC PCB boards, FANUC CNC controls and FANUC CNC repair services.