1154

Common Causes

• Input voltage drop, power failure, blown input fuse, or momentary power interruption (low voltage)
• Faulty power unit (abnormal control power or high voltage)
• Regenerative circuit overload or faulty regenerative resistor circuit
• Heat sink overheating from failed cooling fan or blocked airflow

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code X=0 = DC voltage alarm; ZZ = detected DC voltage (hex, 3.9 V units); code X=1 = Abnormal input voltage; ZZ = detected AC voltage (hex, 3.1 V units); code X=2 = Abnormal control power; ZZ: 1=+5V, 2=+12V, 3=-12V abnormal; code X=3 = Abnormal control status; ZZ: 1=converter overcurrent, 2=bad power element, 3=converter short, 4/5=regenerative circuit fault; code X=4 = Overload in regenerative circuit; code X=5 = Heat sink overheat; code X=6 = CPU error
2. 2Read the code's X digit to branch: 0=DC voltage alarm, 1=abnormal input voltage, 2=abnormal control power, 3=abnormal control status, 4=regenerative overload, 5=heat sink overheat, 6=CPU error.
3. 3For X=1 (input voltage) or low DC voltage: with proper lockout, check the shop supply voltage, input fuses in the power circuit, and look for signs of a momentary power interruption before suspecting hardware.
4. 4For X=2 (control power), ZZ tells which rail: 1=+5V, 2=+12V, 3=-12V abnormal — the power unit itself is the likely faulty part.
5. 5For X=3, ZZ identifies converter overcurrent, power element failure, converter short, or regenerative circuit fault — lock out and allow DC bus to discharge before opening the cabinet to inspect.
6. 6For X=5 (heat sink overheat), check the unit cooling fan operation and clear any blocked heatsink fins or filters.
7. 7If voltage supply and cooling are good and the alarm persists, the power unit is faulty — record the alarm number, full code and object and contact Okuma service.