Circuit Board A20B-2902-0277 A2OB-29O2-O277 A20B29020277

A20B-2902-0277 | FANUC Series 16/18/160/180 Model B 9-Inch High-Resolution CRT Control Module — CRTC / OPT1 Plug-In / FS16-MB / FS18-MB

CRTC Modules in the Series 16/18 Model B Generation

The FANUC Series 16/18 Model B (16-MB, 16-TB, 18-MB, 18-TB) CNC systems use a modular display architecture. The display function is not fixed into the main board — it is provided by a plug-in CRTC (CRT Controller) daughter board that installs into the OPT1 (Option 1) slot of the CNC control unit.

Within the A20B-2902-027x CRTC module family for the Series 16/18-B, several variants exist to match different monitor configurations:

A20B-2902-0270: 14-inch colour CRT variant A20B-2902-0271: 9-inch CRT standard resolution A20B-2902-0272: VGA output variant (for LCD or VGA monitor) A20B-2902-0273: 14-inch CRT alternative A20B-2902-0275: VGA variant A20B-2902-0276: 9-inch CRT alternative A20B-2902-0277: 9-inch high-resolution CRT A20B-2902-0278: VGA variant

The A20B-2902-0277 is specifically the high-resolution 9-inch CRT variant — confirmed for FS16/18/160/180-MB systems with a high-resolution monochrome CRT operator display.

Key Product Information

High-Resolution CRT — What It Means in Context

In FANUC CNC operator displays, "high-resolution" distinguishes the enhanced display capability from standard-resolution CRT modules fitted on the same series:

Standard resolution: Used for text-dominant displays showing axis positions, programme content, tool offsets, and alarm codes — sufficient for the CNC's basic character-based interface.

High resolution: Produces more pixels per unit area on the 9-inch screen — enabling finer character rendering, sharper graphics, and more display content per page without loss of readability. For CNC systems where graphical tool path display, higher-density programme listing views, or more detailed diagnostic screens are required, the high-resolution CRT module provides the display quality that the standard module cannot.

The A20B-2902-0277 drives a 9-inch CRT at the higher pixel density that the high-resolution display configuration requires.

OPT1 Plug-In Architecture

The Series 16/18 Model B CNC control unit's display is served by the OPT1 board — a dedicated expansion slot board within the CNC's card rack. The CRTC module plugs into a socket on this OPT1 board, connecting the CRTC's video output to the CRT monitor's deflection and intensity circuits.

Replacing the A20B-2902-0277 requires:

1. Opening the CNC control unit and locating the OPT1 board
2. Removing the failed CRTC module from its socket on the OPT1 board
3. Fitting the replacement module into the same socket
4. Closing and restoring power — no parameter changes needed

Application Scenarios

16-MB CNC display failure: A FANUC 16-MB machining centre loses its operator display — the 9-inch CRT goes blank or shows corrupted content. CNC operation continues normally. Diagnosis isolates the fault to the A20B-2902-0277 CRTC module. Replacement restores the display.

Display quality maintenance: A high-resolution 9-inch CRT on an 18-MB CNC develops distorted character rendering due to ageing CRTC module components. Replacing the A20B-2902-0277 restores display quality without replacing the CRT monitor itself.

FAQ

Q1: How is A20B-2902-0277 different from A20B-2902-0271 (also a 9-inch CRT module)?

Both are 9-inch CRT CRTC modules for the Series 16/18-B family, but the 0277 is the high-resolution variant and the 0271 is the standard-resolution variant. The high-resolution version generates more pixels per scan line, producing finer character and graphics rendering on the same physical 9-inch screen. Confirm which variant is installed on the specific CNC by checking the part number on the board label before ordering.

Q2: Can the A20B-2902-0277 be fitted in a Series 16/18 Model C (MC) CNC?

Compatibility between B and C configurations depends on the specific OPT1 board variant and CNC system version. Confirm from the specific CNC's spare parts documentation whether the 0277 is specified for the installed system configuration.

Q3: What symptoms indicate the A20B-2902-0277 has failed versus the CRT monitor tube?

A failed CRTC module typically causes sudden, complete loss of display content — the CRT goes dark without the gradual dimming that accompanies tube ageing. A failing CRT tube shows progressive symptoms: reduced brightness, loss of focus, geometric distortion. If the 9-inch CRT is dark but the CNC operates normally (axes move, programmes run, alarms clear), and testing the CRT with an external signal confirms the tube is intact, the A20B-2902-0277 CRTC module is the replacement target.

Q4: Does replacing A20B-2902-0277 require any CNC parameter adjustments?

No. The CRTC module is a display hardware component — it does not store CNC parameters. After fitting the replacement A20B-2902-0277 and powering the CNC, the display should restore immediately. If the display format appears incorrect (wrong character size or scaling), check whether the CNC's display type parameter matches the installed module configuration.

Q5: Is the A20B-2902-0277 repairable if the complete module has failed?

The A20B-2902-0277 is an SMD (Surface Mount Device) construction module. Component-level repair by a specialist CNC electronics service centre is technically possible for faults involving identifiable failed components (oscillator failure, voltage regulator fault). For production-critical machines, direct board replacement is the faster resolution. Repair is a viable option when the replacement module is unavailable or where the cost of repair is significantly lower.