Fanuc Drive Board A16B-1200-0720 A16B12000720 A16B-12OO-O72O

FANUC A16B-1200-0720 | S-Series 2-Axis Servo Drive PCB — A16B-1200 Series / Dual-Axis / AC Servo Control

Dual-Axis Servo Control in the A16B-1200 Series

The A16B-1200-0720 is a 2-axis servo drive control PCB from FANUC's A16B-1200 series, designed for S-series AC servo drive systems in CNC machine tools. In the S-series servo drive architecture, the servo drive module handles the closed-loop current and position control for the connected servo axes. The A16B-1200-0720 controls two axes simultaneously — L-axis and M-axis — from a single board, enabling synchronized two-axis motion within the drive module it serves.

The S-series was FANUC's analogue interface servo drive generation that preceded the Alpha series. Machines built on S-series servo drives continue in production service. The A16B-1200-0720 is the control PCB component within the 6058 servo drive assembly — identifying and replacing this board specifically, rather than the complete drive unit, is the component-level repair path for S-series drive failures where the control card is the fault source.

Key Specifications

Board-Level Repair vs Drive Replacement

The 6058 servo drive module is a complete unit with the A16B-1200-0720 control PCB as an internal component. Identifying whether a servo drive fault originates in the control PCB or the power stage determines whether board-level repair is the appropriate path.

Control card faults typically produce alarm codes on all axes controlled by the board simultaneously — when L-axis and M-axis alarms appear together with confirmed good motors and cables, the A16B-1200-0720 is the primary suspect. Power stage faults produce overcurrent, phase loss, or transistor alarms specific to the affected circuit, usually on a single axis or as a load-dependent fault.

Confirm the exact part number from the installed board's label before ordering. Adjacent A16B-1200 variants serve different axis counts and drive configurations within the S-series family.

FAQ

Q1: What FANUC CNC generation uses the A16B-1200-0720?

The A16B-1200 series servo control PCBs are associated with FANUC's S-series servo drive platform — the generation that preceded the Alpha series. S-series servo drives interfaced with FANUC Series 0, 3, 5, 6, and 10/11/12 CNC controls using the analogue PWM interface. Confirm the CNC and drive generation from the machine documentation before specifying this board.

Q2: Can the A16B-1200-0720 be tested before installation?

Functional verification of a servo drive control PCB requires running the complete drive module under motor load — conditions that cannot be replicated without the full drive assembly and a connected motor. A board confirmed good in donor machine testing is the most reliable verification method. Bench power-on testing without a load only confirms the board powers on without basic faults.

Q3: What alarms indicate the A16B-1200-0720 has failed?

Simultaneous alarms on both L-axis and M-axis — the two axes controlled by this board — with confirmed good motors and cables point to the control PCB. VRDY (velocity ready) faults at startup or alarm codes indicating servo communication failure also point to the control card when the drive wiring and motor are confirmed healthy.

Q4: Are there switch or jumper settings on the A16B-1200-0720 that must be matched?

Servo drive control PCBs in the A16B-1200 series may carry configuration switches for axis interface parameters. Before removing the original board, photograph or record all switch positions. The replacement board must be configured identically. Incorrect switch settings produce axis alarms or incorrect drive behaviour that does not match the CNC's programmed motion parameters.

Q5: Where is the A16B-1200-0720 sourced?

Through the FANUC S-series servo drive aftermarket — FANUC component dealers, industrial CNC repair specialists, and tested surplus suppliers. Confirm A16B-1200-0720 specifically from the installed board's label. The A16B-1200 family contains multiple variants; the -0720 suffix identifies the specific 2-axis configuration for the 6058 drive module.