What Does Alarm 52.3 Mean?
According to the Mitsubishi MR-J4 series servo amplifier manual, Alarm 52.3 means "Excess Droop Pulse 2”.
In simple terms, it means that the driver has detected an instantaneous pulse fluctuation in the output or feedback signal that exceeds the set threshold. These pulses typically occur during sudden load changes, shocks, or voltage fluctuations.
In other words, this is not a normal "overload” or ‘stall’, but a "system dynamic abnormality”. The drive monitors the pulse overrun and will actively alarm and protect the system.
In the actual maintenance, we found that this alarm is often related to mechanical shock, load changes, line feedback abnormalities or parameter settings are too sensitive related.
We Commonly See Several Causes
The following categories are the most common causes of Mitsubishi 52.3 alarms that Songwei encounters during maintenance - basically covering more than 90% of the cases.
1. Mechanical shock or sudden load change
This is the most common type. This is the most common type. For example, if the machining head hits the tool, the slide is pushed to the limit, or the axis is suddenly pushed backwards by an external force, the drive will detect a momentary pulse that exceeds the limit, and then the alarm will be triggered.
Sometimes customers say "obviously not moving”, but in fact, the motor has just had a moment of impact by external forces.
2. Encoder or feedback line signal abnormality
Encoder feedback instability, signal line broken strands, loose connectors, U/V/W connection error, etc., will also be misjudged by the system as "pulse abnormality”. Especially the old machine or cable repeatedly bending equipment, this type of failure is very typical.
3. Power supply voltage fluctuations or low bus voltage
Bus Voltage Drop (Bus Voltage Drop) will also trigger 52.3. For example, in the factory, a number of equipment started at the same time, the power grid instantly sunk, the driver detects the bus voltage instability, it will also be judged as a pulse overrun.
4. Parameter settings are too sensitive
If the servo parameters of the"Droop Pulse Threshold”or acceleration and deceleration time constants are set too small, the system's tolerance is too low, the normal fluctuations may be treated as abnormal pulses, and thus the alarm.
5. Drive internal module aging or detection circuit failure
If the mechanical and wiring are not a problem, but the alarm occurs repeatedly, most likely the drive internal logic board or power module aging. Especially the use of many years of amplifiers, this situation can often be reproduced on the repair bench.
Our Troubleshooting Process When Repairing
Although each unit is different, we usually check step by step along the following lines:
1. Safely disconnect the power and wait for the discharge
First turn off the main power and wait for the discharge lamp to go out completely (usually 10-15 minutes), then start checking.
Do not save this step, both for safety requirements, but also to avoid misjudgment.
2. Observe the timing of the alarm
Is it reported during operation or just after the power is turned on? Is it when moving the shaft, or in a state of shutdown? These details are very important to help us determine whether it is a mechanical shock or signal abnormality.
3. Check the mechanical parts
Manually rotate the relevant axis to see if there is any stagnation, abnormal noise or collision. Guide rails, ball screws, couplings, tool holders, etc. should be looked at a circle.
Many times just a slight mechanical top to the limit can cause a pulse overrun.
4. Check the encoder and signal wires
Unplug the encoder wires and make sure the interface is solid and not broken. Use a multimeter to measure the on-off, and use an oscilloscope to look at the signal waveform.
If you find a certain line signal drift or noise, it is recommended to replace it.
5. Check the power supply and bus voltage
Measure the bus voltage under load to see if it is within the rated range.
If a significant voltage drop is found, consider voltage stabilization or improving the quality of the power supply.
6. Check servo parameters
Some devices set the acceleration and deceleration time too short in order to pursue the response speed, or the position loop gain is too low, which will cause the fluctuation over the limit.
You can try to restore to the default parameters and test again.
7. Verify on the test bench
If all the above are OK, we will put the drive on the dedicated
Mitsubishi test bench to simulate the operation.
See if it still alarms under different loads to determine if there is any problem inside the drive.
Repair or Replace? This is what we usually recommend
* Repair is recommended: if the problem is found to be a signal line, parameter or external mechanical problem; or if the drive is only damaged by an individual module, and spare parts are readily available.
* Replacement: If the main power or logic board has failed multiple times, the model has been discontinued, or the cost of repair is close to the price of replacement.
Songwei will issue a full report after each test: including test data, alarm recurrence, repair feasibility and cost comparison, so as to facilitate the customer's decision.
How to Prevent 52.3 Alarms from Recurring
We have learned a few useful lessons when maintaining our customers' equipment:
* Clean the control cabinet and check the fan regularly to avoid heat buildup;
* Check the mechanical transmission parts to make sure they are smooth and free from jamming;
* Tighten the encoder connector regularly to prevent the signal line from loosening;
* Keep the power supply voltage stabilized to avoid frequent voltage fluctuations;
* Do not set the parameters too "aggressively”, especially the acceleration and deceleration time and ring gain;
* Do no-load and under-load testing of the drive once a year to detect early abnormalities.
Songwei's Support
We, Songwei, specialize in the sales, maintenance and testing services for servo drives of Mitsubishi, Fanuc, Siemens, Okuma, Heidenhain and other brands.
We have a perfect Mitsubishi test platform, which can simulate the actual load condition and quickly locate the cause of 52.3 alarm.
We can provide:
* Mitsubishi full series servo drive, servo motor (new, used, refurbished parts)
* Professional maintenance and inspection, provide test reports
* Global delivery and technical support
* One-stop program: diagnosis, repair, replacement, testing, after-sales protection
If you encounter Mitsubishi Alarm 52.3 and are not sure whether it is a drive problem or a mechanical problem, you can send us the equipment model number and alarm situation, and we will help you analyze and give you a feasible solution.
Summary
Mitsubishi Alarm 52.3 indicates that the drive detects excessive sag pulse signals. Common causes include mechanical shock, abnormal feedback signals, voltage fluctuations or improper parameter settings.
By following the right steps - mechanical, wiring, parameterization, and then verification at the test bench - you can quickly identify the problem.
We at
Songwei don't just want to help our customers fix alarms, we want to help them keep their systems running stably for the long term. Less equipment downtime means more money for production.
