Okuma Alarm A-1120 – Overload Detected
Okuma Alarm A-1120 indicates that an overload condition has been detected in an external motor or drive system.
This alarm is generated when the CNC control receives an overload signal from the machine’s protection system, typically through the “General Overload Detect” circuit.
The overload detection system monitors the load on motors and other machine components. If the load exceeds the safe operating limit, the control system triggers Alarm A-1120 to protect the motor, drive electronics, or mechanical components from damage.
Possible causes
Several issues may cause this alarm:
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Mechanical overload on the motor or driven axis
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Spindle or axis motor under excessive load
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Tool jam or mechanical obstruction
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Fault in the motor drive or amplifier
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Overload signal triggered by the protection circuit
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Wiring or sensor problems in the overload detection system
What happens when this alarm appears
When Alarm A-1120 occurs, the CNC control detects that a motor or drive system is operating beyond its safe load limit.
To prevent damage to the machine, the control system usually stops the affected operation or disables the motor until the issue is resolved.
Recommended actions
To troubleshoot this alarm, the following steps are recommended:
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Check for mechanical blockage or excessive load on the machine axis or spindle.
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Verify that the tool or workpiece is not causing abnormal resistance.
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Inspect the motor drive and amplifier for overload indications.
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Check the “General Overload Detect” circuit and related wiring.
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Restart the machine after the issue has been corrected.
Professional repair service
If the alarm continues to appear, the problem may be related to a faulty drive system, motor protection circuit, or control electronics.
Our technicians specialize in Okuma CNC electronics diagnostics and repair, including drive modules, control boards, and servo system components.
