31.05.2025 by Viktor Siebert
Successful Repair: Mitsubishi MDS-C1-SPHX-55 Spindle Drive with Alarm A.32
A Real Case from Our Workshop.
Just recently, a Mitsubishi MDS-C1-SPHX-55 AC Spindle Drive Unit left our workshop. This unit typically operates with a Mitsubishi SJ-V5.5-01 spindle motor.
The customer initially couldn’t determine whether the fault was with the drive or the motor. The motor had already been replaced, but the spindle continued to jerk at low speeds. Even at higher speeds, the drive would randomly shut down with an error. The motor would spin down, and the machine would stop.
Workaround to Stay in Production
To keep production running, the customer reprogrammed the machine to reduce spindle load. Since the error occurred randomly rather than consistently, he said:
“What matters is that I can keep producing.”
Then Came the Bang
After about two months, the device finally gave out—with a loud bang. Alarmed, the customer contacted us, asking:
- Can the device be repaired?
- How long will it take?
- Do you have all the parts in stock?
The drive was permanently showing Alarm A.32.
Known Issue: Alarm A.32
We were already familiar with this unit—and with Alarm A.32, which is among the most common alarms for this type. We’ve seen this scenario before: the customer replaces the motor, cables, even the controller—and in the end, the fault lies in the drive.
In this case, not only had the power transistors exploded, but the housing was also badly damaged, requiring us to source a replacement casing.
Fast Repair – Big Impact
Despite the damage, we repaired the unit within one week. The customer was amazed at how fast it went. Ordering a new unit from the machine manufacturer would have been possible—but only as an exchange. Given the condition of the drive, an exchange wasn’t viable. The customer would have had to pay over €5,000 for a new device.
With us, the repair cost just a quarter of that. We were only about two days slower than the manufacturer’s exchange process. Meanwhile, we’ve added this unit to our exchange inventory—and can compete both in terms of price and turnaround time.
Background on the Fault
Alarm A.32 relates to the power output stage and its control logic. In some cases, the motor or supply cable may also be to blame.
How to Prevent Failures Like This
We are often asked: “What can be done to prevent such failures in the future?”
Here are our recommendations:
- Replace cooling fans regularly
- Clean the unit thoroughly
- Perform preventive overhauls
- React early to signs such as motor jerking or unusual noise
Is a Repair Without Testing Possible?
This was another question the customer raised. He had received an offer from another service provider claiming that a repair without functional testing was possible. Allegedly, all components could be checked visually and electrically with sufficient confidence.
Our technicians have a clear stance:
“That’s pure luck. The chance of success is about 60–70%. But how long it will last is an entirely different question.”
A final load test is absolutely essential. It’s the only way to ensure reliable function.
To mentioned Mitsubishi Drive: Mitsubishi MDS-C1-SPHX-55 or MDSC1SPHX-55 Spindle Drive Unit
Similar type MDS-C1-SPH-55
More details about our Mitsubishi repair services can be found here:
Mitsubishi drive Repair by Industrypart
📞 Feel free to contact us with any questions about your Yaskawa drive technology.
Our expert team is happy to help!
Technical Summary of the Unit
The MDS-C1-SPHX-55 is a spindle drive unit with a rated output of 5.5 kW.
The “HX” in the model name indicates a high-speed version, designed for use in fast, precision CNC applications.
Technical Specifications – Mitsubishi MDS-C1-SPHX-55
| Parameter | Value |
|---|
| Device Type | AC Spindle Drive Unit |
| Model Number | MDS-C1-SPHX-55 |
| Rated Power | 5.5 kW |
| Input Voltage | DC 270–311 V |
| Input Current | 20 A |
| Auxiliary Supply | 1-phase 200–230 V, 0.2 A, 50/60 Hz |
| Output | 3-phase 200 V, 0–833 Hz, 18 A |
| Software Version | BNP-G3000 |
| Manual Number | BNP-C3000 (technical manual reference) |
| Hardware Version | H |
| Manufacturer | Mitsubishi Electric Corporation, Japan |
Alarm List – Common Error Codes on MDS-C1-SPHX-55
| Alarm Code | Description | Possible Cause | Recommended Solution |
|---|
| A.32 | Output stage error (IGBT/driver fault) | – Exploded IGBT module(s) – Malfunction in gate driver/control section | – Replace damaged output modules – Repair driver circuitry |
| A.10 | Overcurrent on output (during start/load) | – Motor cable short – Defective motor – Overload | – Check motor and cables – Test overcurrent protection |
| A.04 | Overtemperature of drive | – Fan failure – Blocked ventilation – Excess ambient temperature | – Replace fan – Clean unit – Check installation environment |
| A.70 | Encoder/feedback signal error | – Faulty feedback cable or connector – Defective encoder | – Inspect connections – Replace encoder |
| A.61 | Communication failure with CNC controller | – SH21 cable disconnected – Fault in controller or drive communication | – Check SH21 bus cable – Verify parameter settings |