Okuma OSP codes
AxisMD

axismd.ai

Okuma OSP Controller

Power Supply · Intermediate

Alarm 0854

Okuma OSP Alarm P 0854 - MCS Power supply unit error

The MCS power supply unit has reported an internal error for the indicated axis or spindle system. The code identifies the failure type — DC bus voltage, input AC voltage, control power, regenerative circuit overload, heat sink overheat, or CPU error — plus the unit's status bits and measured voltage data.

Okuma OSPPower SupplyIntermediate

0854

Okuma OSP Alarm P 0854 - MCS Power supply unit error

MCS Power supply unit error

The MCS power supply unit has reported an internal error for the indicated axis or spindle system. The code identifies the failure type — DC bus voltage, input AC voltage, control power, regenerative circuit overload, heat sink overheat, or CPU error — plus the unit's status bits and measured voltage data.

Common Causes

  • Incoming AC supply low, phase loss, blown input fuse, or momentary power interruption
  • Power unit failure (converter overcurrent, faulty power element, or shorted converter)
  • Regenerative circuit fault or overload during heavy deceleration
  • Heat sink overheating from failed cooling fan or blocked airflow
  • Internal +5V/+12V/-12V control power abnormality in the power unit

Troubleshooting Steps

  1. 1Read the code number shown with the alarm: code X=0 = DC voltage alarm; ZZ data is the detected DC voltage in hex (3.9V per count).; code X=1 = Abnormal input voltage; ZZ data is the detected AC voltage in hex (3.1V per count).; code X=2 = Abnormal control power; ZZ shows which rail failed (1=+5V, 2=+12V, 3=-12V).; code X=3 = Abnormal control status; ZZ identifies converter overcurrent, power element fault, converter short, or regenerative circuit fault.; code X=4 = Overload in the regenerative circuit.; code X=5 = Heat sink overheat.; code X=6 = CPU error in the power unit.
  2. 2Read the code on screen: the X digit is the alarm number (0=DC voltage, 1=input voltage, 2=control power, 3=control status, 4=regenerative overload, 5=heat sink overheat, 6=CPU error) and ZZ gives the measured data.
  3. 3X=1 (abnormal input voltage): before opening the cabinet, lock out and verify the shop supply — measure all three phases at the machine disconnect, and check the input fuses in the power circuit for a blown phase.
  4. 4X=0 (DC voltage alarm): the ZZ data is the detected DC bus voltage (hex, 3.9V per count); a low reading points back to the input supply or a failing converter section in the power unit.
  5. 5X=2 (control power abnormal): ZZ tells which rail failed (1=+5V, 2=+12V, 3=-12V); with power locked out and DC bus discharged, check the power unit — this indicates an internal power unit fault.
  6. 6X=3 (control status): ZZ distinguishes converter overcurrent, abnormal power element, converter short, or regenerative circuit fault; inspect the power unit and regenerative resistor wiring after lockout and discharge.
  7. 7X=5 (heat sink overheat): check the power unit cooling fan operation and clear dust/chips from the heat sink and cabinet filters before condemning the unit.
  8. 8If the alarm persists after supply, fuses, and cooling checks, the power unit itself is suspect — record the full code and contact Okuma service.

Seeing Multiple Alarms?

Seeing another alarm with this one? Enter the code.

Get machine-aware diagnosis

AxisMD logs alarms against your actual machines, tracks patterns, and gives AI context your manual doesn't have.

Start free

Was this guide helpful?

Always verify with your machine manual or a certified technician before performing service procedures.