The FANUC A16B-3200-0420 is a Main CPU PCB and Master PCB used in compatible FANUC Series 16i, 160i, and 160is Model B stand-alone CNC control units.

FANUC maintenance documentation identifies the exact board as the 16i/160i/160is Main CPU Board, with hardware identification code 3X0C. It forms the main hardware platform for the CPU card, memory modules, axis-control hardware, display-control card, communication interfaces, and other CNC functions installed in the control unit.

The term stand-alone refers to the FANUC control architecture in which the CNC basic unit is installed separately from the LCD or operator panel. It does not mean that the A16B-3200-0420 can operate independently without the corresponding CPU card, memory, system software, back panel, power supply, display interface, and machine data.

Depending on the original configuration, the board may support interfaces associated with:

• RS-232C serial communication
• FANUC I/O Link
• Serial spindle and position-coder signals
• Analog output and high-speed digital input
• LCD/MDI display communication
• Memory-card operation
• Servo-axis and CNC option cards

The exact available functions depend on the installed card configuration and board revision.

Organic search results commonly describe the A16B-3200-0420 as:

• FANUC 16i/160i Model B Main CPU Board
• FANUC 16i-B Master PCB
• FANUC 160i-B CNC Main Board
• FANUC Stand-Alone Main CPU PCB
• FANUC CNC Control Motherboard

The board may be suitable for replacing a confirmed fault associated with CNC startup failure, CPU alarms, failure to recognize installed cards, intermittent system operation, communication faults, memory-related errors, or physical damage to the PCB.

• Main-board startup and interface functions tested before shipment
  
• In stock and prepared for prompt dispatch
  
• Worldwide DHL, UPS, and FedEx shipping

Product Details

• Brand: FANUC
• Part Number: A16B-3200-0420
• Alternative Format: A16B32000420
• Official Product Type: Main CPU Board
• Alternative Product Name: Master PCB / CNC Main Board
• Primary CNC Family: Series 16i / 160i / 160is
• Control Generation: Model B
• Control Architecture: Stand-Alone Type
• Hardware Identification: 3X0C
• Board Structure: Configurable / Card-Dependent
• Product Series: A16B-3200
• Application: Compatible FANUC i-Series CNC Controls
• Category: FANUC Main Board / CNC CPU PCB
• Supply Configuration: Bare, partially populated, or fully populated, subject to stock
• Testing: Inspected and tested under an applicable FANUC CNC configuration

The main-board designation, Model B system families, hardware ID, and stand-alone control structure are documented in FANUC maintenance and parts information.

Documented Basic Units

FANUC documentation lists the following stand-alone basic units for the Series 16i/160i/160is Model B hardware structure:

• A02B-0281-B801: Basic Unit with One Slot
• A02B-0281-B803: Basic Unit with Three Slots

The A16B-3200-0420 should be matched with the original basic unit, back panel, slot arrangement, power supply, and installed card configuration.

Documented Card Configuration

The A16B-3200-0420 is a configurable main PCB. FANUC documentation lists multiple card options for this control generation, including:

• A20B-3300-0310: CPU Card with 16MB DRAM
• A20B-3300-0311: CPU Card with 32MB DRAM
• A20B-3300-0340: LCD/MDI Display Control Card
• Standard and high-speed CPU card configurations
• Axis-control and CNC option cards

These are documented possibilities within the hardware family and are not guaranteed to be included with every supplied A16B-3200-0420 board.

A supplied unit may therefore be:

• Bare Master PCB
• Partially populated main board
• Main board with CPU and memory cards
• Fully populated machine-specific control assembly

The included modules should be confirmed before quotation and shipment because configuration has a major effect on compatibility and price.

Specification Revision Clarification

The original FANUC B-63525EN/02 documentation identifies:

• A16B-3200-0420: 16i/160i/160is Main CPU Board
• A16B-3200-0421: 18i/180i/180is Main CPU Board
• A16B-3200-0425: 21i/210i/210is Main CPU Board

A later FANUC specification-change sheet lists:

• A16B-3200-0427: Later 16i/160i/160is Main Board
• A16B-3200-0420: Old-specification board for selected 18i/180i/180is-MB5 configurations
• A16B-3200-0429: Later 18i/180i/180is Main Board
• A16B-3200-0421: Earlier 18i/180i/180is specification

This revision history means the exact A16B-3200-0420 application should be confirmed from the original CNC system rather than assuming every unit belongs to only one system designation.

Data Backup and Programming Warning

Before replacing the main CPU board or any mounted card, FANUC instructs maintenance personnel to back up the CNC’s SRAM contents, including parameters and programs, because data may be lost during replacement. If the SRAM checking method or memory configuration changes, the saved data may need to be restored after installation.

Depending on the original control, the backup should include:

• CNC parameters
• PMC ladder and PMC parameters
• Part programs
• Macro programs and variables
• Tool offsets
• Work-coordinate data
• Pitch-error compensation data
• Servo and spindle parameters
• Keep relays, timers, and counters
• Ethernet and communication settings
• System software and option information
• SRAM backup files

The statement “all parameters and programs must always be reloaded” is too absolute. If the original memory and CPU modules are transferred correctly and their data remains intact, a complete reload may not always be necessary. However, a verified backup should always be prepared before replacement.

Compatibility Note

Before ordering the A16B-3200-0420, please verify:

• Complete FANUC PCB number
• Revision printed after the base part number
• CNC system model shown at startup
• 16i, 160i, 160is, or applicable 18i-MB5 configuration
• Model B stand-alone control structure
• Original basic-unit number
• One-slot or three-slot back-panel configuration
• CPU-card part number and DRAM capacity
• FROM and SRAM memory modules
• Axis-control card and controlled-axis count
• Display-control card
• Communication and optional interface boards
• System software series and edition
• CNC option list
• Availability of the original parameter and SRAM backup
• Whether a bare or fully populated board is required

The A16B-3200-0420 should not automatically be substituted with A16B-3200-0320, A16B-3200-0421, A16B-3200-0425, or A16B-3200-0427 solely because the boards look similar.

Common Use Cases

• FANUC Series 16i-B main-board replacement
• Series 160i/160is Model B controller restoration
• Troubleshooting CNC CPU or startup alarms
• Diagnosis of memory and card-recognition faults
• Repair of intermittent control-system operation
• Transfer of original CPU and memory cards
• Replacement of physically damaged PCB circuitry
• Rebuilding a stand-alone FANUC CNC control unit
• Preparation of a tested spare Master PCB

Sales & Support

Each A16B-3200-0420 Main CPU PCB is inspected and tested under an applicable FANUC CNC configuration before delivery.

The installed CPU, memory, axis, and display-card configuration will be confirmed before shipment. REACO CNC provides PCB repair service, warranty coverage, testing-video support, data-backup guidance, configuration assistance, and technical support for FANUC CNC control systems.

Worldwide delivery is available through DHL, UPS, FedEx, and other express carriers.