Used Fanuc Circuit Board A20B-8101-0400 A20B81010400 A2OB-81O1-O4OO

A20B-8101-0400 | FANUC 30i-A and 31i-A5 Main PCB A4 — Master Board / A20B-8101 Series / LCD/MDI Unit Installed / FS30i Platform

Series 30i-A and 31i-A5 — FANUC's High-End Platform

The FANUC Series 30i/31i/32i platform represents the top tier of FANUC's i-series CNC architecture. Positioned above the Series 16i/18i/21i in processing capability and axis count, the 30i/31i/32i series is designed for the most demanding machine tool applications:

Series 30i-A: FANUC's most capable CNC — supporting up to 9 paths, 32 axes, and 4 spindles. Used on highly complex multi-spindle machining centres, transfer lines, and combined machining systems where no other CNC offers sufficient axis count or programme capability.

Series 31i-A5: A high-performance CNC in the same 3xi family — configured for 5-axis machining with advanced AI servo and spindle control features optimised for 5-axis simultaneous contouring. The "A5" designation identifies this specific 31i-A configuration variant.

The A20B-8101-0400 is the master board that unifies all CNC functions for these platforms.

Key Product Information

A4 vs A5 — Main PCB Types in the 30i Series

Within the A20B-8101 series, the 30i/31i main PCBs come in multiple type designations:

The "A4" and "A5" type designations identify different hardware generations or capability configurations within the same 30i/31i main PCB family. The A20B-8101-0401 (A5 type) is described as "for 30i/31i/32i series Model A without PC function" — suggesting the 0401 is for configurations without the integrated PC option. The A20B-8101-0400 (A4 type) specifically serves 30i-A and 31i-A5.

Application Scenarios

30i-A main board failure: A FANUC 30i-A machining centre system's master board develops a fault — CNC initialisation fails, or persistent communication errors prevent normal operation. After SRAM backup, the A20B-8101-0400 is replaced. SRAM data is restored and CNC operation resumes.

31i-A5 5-axis machining centre maintenance: A 5-axis machining centre with 31i-A5 control undergoes main PCB replacement during a scheduled control system refurbishment.

FAQ

Q1: What SRAM data must be backed up before replacing A20B-8101-0400?

All machine-specific data stored in SRAM must be backed up via the CNC's ALL IO or data management function before beginning the replacement. This includes: CNC parameters (axis settings, software limits, gains), PMC ladder programme, part programmes, tool offsets, work coordinate offsets, and custom macro variables. Without this backup, the data is lost permanently when the board is removed.

Q2: Is the CPU module transferred when replacing A20B-8101-0400?

The CPU module plugs into the master board. When replacing the master board, the CPU module is typically transferred to the replacement board — the CPU module itself is not the failed component. Confirm from the FANUC 30i-A maintenance manual whether the CPU module transfer is specified for the replacement procedure.

Q3: What is the difference between A20B-8101-0400 (A4) and A20B-8101-0401 (A5)?

The A4 type (A20B-8101-0400) is confirmed for 30i-A and 31i-A5. The A5 type (A20B-8101-0401) is confirmed for 30i/31i/32i series A without PC function. The boards serve different configurations within the 30i-A/31i platform and are not interchangeable.

Q4: What power supply module works with A20B-8101-0400?

CNC-Shopping confirms the adjacent A20B-8101-0401 is "mounted with FANUC FS30i Power supply module A20B-8101-0010." The A20B-8101-0400 in the same master board family uses the same FS30i power supply (A20B-8101-0010).

Q5: Can A20B-8101-0400 be used in 32i-A systems?

The product description specifically identifies 30i-A and 31i-A5 compatibility. The Series 32i-A is in the same hardware family but is a different CNC variant.