Okuma CNC Alarm 1400 — What It Means
Alarm 1400 on an Okuma CNC machine indicates an encoder error on a servo axis. The Okuma OSP control detected a problem with the position feedback signal from the servo motor’s built-in encoder (Okuma uses proprietary absolute encoders on most models). This alarm means the control cannot verify axis position and will not allow axis motion until the encoder fault is cleared. Alarm 1400 series (1400, 1401, 1402) covers different axes and encoder fault subtypes.
Common Causes
- Encoder battery low or dead — Okuma absolute encoders use a backup battery to retain position data when the machine is powered off. A dead battery causes the encoder to lose its absolute position and trigger an alarm on power-up.
- Encoder signal fault — The encoder itself has developed a fault due to internal failure, contamination of the optical disk, or bearing failure.
- Encoder cable damage — The feedback cable between the encoder and the servo drive has a broken conductor or damaged connector.
- Servo drive encoder input fault — The encoder interface circuit on the Okuma SERVOPACK or drive module has failed.
Step-by-Step Fix {#fix}
- Check the encoder battery — On Okuma machines with absolute encoders, the battery bank is typically located in the electrical cabinet or on the machine base. Check the battery voltage with a multimeter. Okuma batteries should be above 3V. Replace if below 3V.
- Perform an encoder battery reset — After replacing the battery, perform the Okuma battery replacement procedure (typically: clear the alarm, then perform a reference point return for all axes). Follow the procedure in the Okuma maintenance manual for your machine.
- Power cycle the machine — After battery replacement, perform a full power cycle and allow the control to initialize. Alarm 1400 should clear if the battery was the cause.
- Inspect the encoder cable — Trace the feedback cable from the servo motor to the servo drive. Look for cable damage, pinching, or areas of wear. Flex the cable along its length to identify intermittent breaks.
- Inspect the encoder connector — At both the motor end and the drive end, verify the encoder connector is fully seated and free from moisture or contamination. Reseat the connector firmly.
- Contact Okuma service for encoder replacement — Okuma absolute encoders are proprietary devices. Replacement requires an OEM Okuma encoder and a calibration procedure that must be performed by an Okuma-certified technician.
- Reset and verify — After hardware repairs, reset the alarm and perform a reference return on the affected axis. Run the axis through its full travel range and confirm no alarm recurrence.
Parts Often Needed
| Part | Notes |
|---|---|
| Encoder backup battery | Amazon | Okuma-specific lithium battery; replace every 3–5 years preventively |
| Encoder feedback cable | Amazon | OEM Okuma cable; match to motor and drive model |
| Absolute encoder (Okuma OEM) | Amazon | Requires Okuma service for replacement and calibration |
| Servo drive (SERVOPACK) | Amazon | Replace if drive’s encoder interface has failed |
When to Call a Pro
Okuma absolute encoder replacement and post-replacement calibration must be performed by an Okuma Factory Automation (OFA) certified technician. Incorrect calibration will result in positioning errors that can damage the machine or workpiece.