17.06.2025 by Viktor Siebert
Emergency Call from North Rhine-Westphalia – Spindle Amplifier with a High-Pitched Whistle Fanuc Spindle Amplifier A06B-6102-H215#H520
Just a few days ago, we received an urgent call from North Rhine-Westphalia. A long-time CNC service provider specializing in tool and mold making reported a problem with one of their Fanuc machines. The spindle would regularly come to a stop – accompanied by a loud, high-pitched whistle that echoed through the entire hall. Employees were frustrated, the customer under pressure. The diagnosis: Fanuc Spindle Amplifier A06B-6102-H215#H520 defective.
First Inspection – A Fan That Was No Longer a Fan
As soon as the unit arrived at our facility, we brought it straight to our inspection area. Upon opening the housing, we were shocked:
The internal fan wasn’t just broken – it was practically non-existent. Only fragments of the casing remained; the rotor had completely vanished. The fan blades? Gone without a trace. It appeared the plastic had degraded over time and shattered at high speed.
Another striking observation: a shrill whistling noise exactly at 1000 RPM. A typical resonance frequency triggered by insufficient cooling and thermal stress on specific components. Eventually, the amplifier would shut down with an overload error.
In-Depth Analysis – Damage Caused by Missing Airflow
We conducted a thorough examination:
- Power modules showed visible heat discoloration
- Two capacitors in the intermediate circuit were bulging
- The heatsinks of the output stage were completely clogged with dust
- The temperature sensor was giving inaccurate readings due to heat exposure
Without the cooling fan, the unit was forced to operate under permanent thermal stress. This resulted in secondary faults that would not have been detected without a detailed diagnosis.
The Repair – More Than Just Replacing a Fan
The repair involved:
- Complete replacement of the internal fan with an exact-match new unit
- change of all electrolyt capacitors and power modules
- Cleaning and reconditioning of the heatsink
- Replacement of all high-voltage electrolytic capacitors
- Reinstallation and stabilization of the temperature sensor
- Re-soldering of critical power connections
- Ultrasonic cleaning of all PCB assemblies
We then performed load testing under real operating conditions – full spindle load for six hours without any faults or temperature warnings.
Return Shipment & Customer Feedback
Only three working days later, the amplifier was already on its way back to the customer. The next day, we received this feedback:
“The machine finally runs without any issues. No more whistling, no more downtime. Excellent service, as always – thank you!”
Conclusion – Small Cause, Major Consequences
A defective fan can cause serious secondary damage in a high-performance spindle amplifier like the A06B-6102-H215#H520. Our experience clearly shows:
Regular visual inspections and preventive maintenance can help avoid costly production downtimes. And if something does go wrong – we’re here to help.
To mentioned Fanuc Drive: Fanuc Spindle Amplifier A06B-6102-H215#H520
More details about our Fanuc repair services can be found here:
Fanuc drive Repair by Industrypart
📞 Feel free to contact us with any questions about your Fanuc drive technology.
Our expert team is happy to help!
Device Specifications (Technical Data)
| Parameter | Value |
|---|
| Model | A06B-6102-H215#H520 |
| Device Type | Spindle Amplifier Module |
| Rated Input Voltage | 283 – 325 V AC |
| Maximum Output Voltage | 230 V~ |
| Rated Power Output | 17.5 kW |
| Rated Output Current | 63 A |
| Input Frequency | 3-phase, 50/60 Hz |
| Manufacturer | FANUC LTD, Yamanashi, Japan |
| Protection Class | CE-compliant, UL-certified |
| Manual Reference | B-65162 (standard manual) |
Operating Environment & Compatibility
The A06B-6102-H215#H520 module is typically used in CNC machines equipped with FANUC control systems. It is compatible with:
- α-series spindle motors (e.g. α12, α15)
- FANUC Power Supply Modules such as PSM–HV
- Optional components: PSMC–HV capacitor module, AC reactor, regenerative discharge unit
- Control via CNC through FSSB or serial communication interface
Environment:
- Operating Temperature: 0–55 °C (non-condensing)
- Humidity: <90% relative
- Must be installed inside a control cabinet with forced cooling
Functional Description
The spindle amplifier module controls the speed and torque of the connected spindle motor. It converts DC-link voltage (from the power supply module) into 3-phase AC voltage and performs:
- High-frequency PWM modulation for precise output control
- Monitoring of current, voltage, and internal temperature
- Interface communication with the CNC controller
- Support for spindle orientation and C-axis contouring control
- Emergency stop functionality and fault detection
Alarm Codes and Troubleshooting
| Alarm Code | Description | Cause / Solution |
|---|
| AL-01 | Output Overcurrent | Check spindle motor and wiring for short circuit |
| AL-02 | Overvoltage | DC link voltage too high, inspect power regeneration system |
| AL-03 | Overheat | Cooling failure, clean unit and replace the fan |
| AL-04 | Overspeed | Feedback/encoder issue, check encoder and connections |
| AL-11 | CPU Alarm | Internal control failure, reset unit or replace |
| AL-12 | Parameter Error | Incorrect parameters, verify all settings |
| AL-13 | Communication Error | Interface issue with CNC, check cabling and connectors |
| AL-22 | Fan Alarm | Fan malfunction detected, replace fan |
| AL-29 | Spindle Motor Overload | Motor thermal protection triggered, check load and settings |
