FANUC A20B-8101-0790 – Main CPU/Control PCB for FANUC Series 0i-D Platforms

The FANUC A20B-8101-0790 is a factory CPU/control board used on many FANUC Series 0i-D and 0i Mate-D CNC configurations. From my experience, shops usually fit this board as the “brains” of the control, handling motion control, PMC logic, and field communications over FSSB to Alpha i-series drives. If you’re dealing with a down machine due to a failed main PCB or intermittent resets, this part is typically the right place to look. You might notice that it integrates the high-speed FSSB link and supports standard CNC comms like RS-232C, with Ethernet available on certain sub-versions.

Our Order Placement Process and Guarantees

• Warranty: 365 days
• Delivery: 1 week if in stock; no more than 1 month at the latest
• Payment: 50% advance payment; full payment prior to delivery
• Express Options: FedEx, UPS, DHL
• Testing & Packaging: Professionally inspected, ESD-safe packaging; we can support photo/video verification before shipment in many cases

Key Features

• Main CPU board for 0i‑D/0i Mate‑D – Serves as the central processor and control interface within the FANUC 0i‑D family.
• FSSB drive interface – Fiber serial link to FANUC Alpha i-series servo/spindle amplifiers for reliable, high-speed motion control.
• PMC and I/O Link support – Coordinates ladder logic and interfaces with FANUC I/O Link modules used by many machine builders.
• Standard CNC communications – RS‑232C for DNC/backup; Ethernet is present on many sub-versions (availability can vary by board revision).
• Non-volatile storage compatibility – Works with FANUC memory devices used for parameters, programs, and ladder (depending on system configuration).
• Drop-in replacement – Designed to mount into the 0i‑D backplane with standard connectors; no mechanical modifications in typical cases.

Technical Specifications

Application Fields

This board is typically found in:

• CNC machining centers and vertical mills running 0i‑D
• CNC lathes/turning centers (including 0i Mate‑D builds)
• Cylindrical/grinding machines with FANUC 0i‑D control packages
• Special-purpose machines where builders standardized on 0i‑D architecture

One thing I appreciate is how predictable the retrofit process can be if the sub-version matches your existing board. We’ve seen shops get a machine back in cycle the same day by swapping this PCB and restoring backup data.

Advantages & Value

• Reliability: FANUC 0i‑D hardware is known for long service life; failures tend to be predictable and repairable.
• Compatibility: Works with Alpha i‑series drives over FSSB and standard FANUC I/O Link modules used by many builders.
• Lower Downtime: Board-level swap with parameter/PMC restore usually gets you running fast, which in many cases saves more than a board repair attempt.
• Technical Support: We can assist with basic matching guidance—e.g., confirming sub‑version, firmware alignment, and backup/restore steps.
• Cost Control: Sourcing the exact A20B-8101-0790 reduces integration risk versus cross‑models, helping avoid hidden commissioning time.

Installation & Maintenance

• Environment: Mount inside a sealed CNC cabinet with adequate ventilation; keep ambient within 0–55 °C and low humidity.
• ESD & Handling: Use a grounded wrist strap, handle by edges, and avoid flexing the PCB. Power down and wait for DC rails to discharge before removal.
• Cabling: Inspect FSSB fiber, I/O link cables, and backplane connectors. Any bent pins or dirty sockets can mimic a faulty PCB.
• Backups: Before swap, save CNC parameters, PMC ladder, macros, offsets, and pitch error tables. After install, restore in the recommended sequence.
• Battery/Memory: Confirm the CNC memory backup battery is healthy; unexpected power loss during restore can cause headaches.
• Firmware Matching: Ensure the new board’s firmware and options match the machine configuration. We typically verify this based on your photo/label details.
• Routine Care: Keep the cabinet filtered and clean; check fan filters quarterly, and schedule periodic parameter/ladder backups.

Quality & Certifications

• Quality System: FANUC production is associated with ISO 9001 quality management.
• CE/UL: Typically used within CE/UL‑compliant CNC systems. Individual board markings can vary by revision.
• RoHS: Many later‑release boards are RoHS compliant; earlier vintages may differ. We can check by part label and date code.
• Warranty: 365‑day coverage from us against functional defects under normal use.

Common Supporting Components (for integration)

• FANUC Alpha i‑series servo and spindle amplifiers (FSSB compatible)
• FANUC I/O Link digital/analog I/O units and operator panel interfaces used on 0i‑D machines
• 0i‑D HMI/display units and panel keyboards matched by the machine builder

Quick note from recent customer feedback: a maintenance team swapped an A20B‑8101‑0790 into a 0i‑D lathe and, after restoring parameters and ladder, cleared FSSB alarms immediately—the only hiccup was a dirty fiber endface. After a simple clean and reseat, the machine was cutting parts the same afternoon. That seems to be the typical experience when the sub‑version is matched properly.