Okuma OSP codes
AxisMD

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Okuma OSP Controller

Servo/Axis · Intermediate

Alarm 1689

Okuma OSP Alarm A 1689 - MCS Rotary encoder 2 error

The MCS drive detected illegal data in Rotary encoder 2 (INA-BEARING type) on the indicated axis. The on-screen code identifies whether the A-phase or B-phase voltage from the encoder is out of range, pointing to a failing encoder element or signal path.

Okuma OSPServo/AxisIntermediate

1689

Okuma OSP Alarm A 1689 - MCS Rotary encoder 2 error

MCS Rotary encoder 2 error

The MCS drive detected illegal data in Rotary encoder 2 (INA-BEARING type) on the indicated axis. The on-screen code identifies whether the A-phase or B-phase voltage from the encoder is out of range, pointing to a failing encoder element or signal path.

Common Causes

  • Rotary encoder 2 (INA-BEARING) internal failure on the A or B phase
  • Damaged encoder cable or connector causing abnormal phase voltage
  • Contamination or bearing-related damage inside the INA-BEARING encoder assembly

Troubleshooting Steps

  1. 1Read the code number shown with the alarm: code XXXX=000A (HEX) = The illegal data is the A-phase voltage; YYYY shows the measured A-phase voltage value.; code XXXX=000B (HEX) = The illegal data is the B-phase voltage; YYYY shows the measured B-phase voltage value.
  2. 2Read the code on screen: the first four digits (XXXX) tell which phase is bad — 000A hex means the A-phase voltage data is illegal, 000B hex means the B-phase voltage data is illegal; the last four digits (YYYY) show the actual faulty voltage value.
  3. 3Note the axis in the alarm object, power down, and lock out before handling encoder wiring.
  4. 4Inspect and reseat the Rotary encoder 2 cable and connectors; check for oil ingress, chafing, or bent pins that could distort the phase voltage.
  5. 5Power up and recheck: if the same phase code returns with sound cabling, the encoder element is faulty — replace Rotary encoder 2 (INA-BEARING) per the manual.
  6. 6If the alarm persists after replacement, record the alarm number, code, and axis and contact Okuma service.

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