FANUC SV0606 means that the cooling fan for the external radiator or cooling fin of the common power-supply module has stopped. In the FANUC αi Series maintenance manual, the CNC displays SV0606, while the applicable αiPS power-supply module displays alarm A.
FANUC's official procedure is to confirm that the radiator cooling fan rotates normally and replace it if defective. The manual also identifies a stopped unit stirring fan on certain power-supply models and an incorrectly seated control printed-circuit board or internal board connector as possible causes.
| Alarm location | Display | Meaning |
|---|---|---|
| CNC | SV0606 / converter cooling-fan alarm | The power-supply radiator cooling fan has stopped |
| Applicable αiPS power supply | A | External cooling-fin fan failure |
| Additional affected fan on certain models | A | The internal unit stirring fan may also have stopped |
| Official repair direction | Fan and assembly inspection | Check fan operation, replace the failed fan, and confirm correct control-board installation |
For surrounding servo and converter alarms, see the FANUC SV Alarm Codes: Servo Amplifier, Drive, Voltage and Overheat.
What Does FANUC SV0606 Mean?
The common power-supply module converts incoming AC power and supplies the DC link used by the connected servo and spindle amplifiers. Its power components generate heat, and an external radiator or cooling fin transfers that heat out of the module. A dedicated fan forces air through the radiator so the power semiconductors and surrounding components remain within their permitted temperature range.
SV0606 is generated when the power-supply module detects that this external radiator cooling fan is not operating normally. The immediate problem is loss of forced cooling, not excessive motor current, encoder feedback, motor insulation, or a servo parameter error.
Typical fault areas include:
- Foreign material, oil residue, or dust obstructing the fan blades
- A loose, partly inserted, damaged, or contaminated fan connector
- Broken fan wiring or conductors near the connector or strain relief
- A worn, seized, slow, or electrically defective fan motor
- Incorrect fan installation or reversed airflow after maintenance
- A stopped unit stirring fan on applicable A06B-6110-Hxxx or A06B-6120-Hxxx power supplies
- A control printed-circuit board or faceplate that is not fully seated
- A loose internal connector between the control and power printed-circuit boards
- A fault in the power-supply fan drive or monitoring circuit
Confirm the Affected Module Before Replacing a Fan
SV0606 concerns the power-supply or converter module, not the servo amplifier inverter. A FANUC cabinet can contain multiple cooling fans, including cabinet fans, heat-exchanger fans, power-supply fans, servo-amplifier fans, spindle-amplifier fans, and internal stirring fans.
Before ordering a replacement, record:
- The complete CNC alarm text and number
- The character shown on each power-supply, servo, and spindle amplifier display
- The complete FANUC power-supply model and every suffix
- The original fan or fan-unit part number
- Connector type, rated voltage, wiring arrangement, fan size, and airflow direction
- Whether the power supply has one external radiator fan, multiple fans, or an additional unit stirring fan
The cited αi Series manual maps SV0606 to alarm A on the αiPS. Some technician notes reproduce the display as “A or 10.” Do not assume that 10 is universal. If the installed unit displays 10, use the maintenance manual for its exact series and full model number before applying the alarm-A procedure.
Safety Before Troubleshooting
The common power-supply module and DC link retain hazardous voltage after incoming power is removed. Fan inspection and replacement must be performed by qualified personnel using the applicable FANUC and machine-builder procedures.
Before touching the fan, connector, faceplate, control board, or module:
- Stop the machine using the approved procedure.
- Isolate the incoming electrical supply and apply lockout/tagout where required.
- Wait the discharge time specified for the installed equipment.
- Confirm that the DC-link charge indicator is off and verify a safe condition.
- Prevent the machine from being restarted while work is in progress.
- Record fan orientation, connector position, cable routing, and screw locations before disassembly.
Never place fingers, tools, or cleaning material into a rotating fan. Do not bypass fan monitoring or continue production with the fan stopped, because the power supply can overheat and suffer secondary damage.
1. Confirm SV0606 and Power-Supply Alarm A
Confirm that the CNC displays SV0606 and that the applicable common power-supply or converter module displays A. Photograph all displays before switching off the machine.
Also record whether the alarm:
- Appears immediately when control power is turned on
- Appears only after the main power is enabled
- Occurs intermittently when the cabinet vibrates
- Appears after the machine has been operating for some time
- Began after fan, control-board, power-supply, or cabinet maintenance
- Is accompanied by abnormal fan noise, low airflow, or another thermal alarm
An alarm that changes when the connector or cable is disturbed suggests a connection or wiring fault. An alarm that appears with a stationary, noisy, or slow fan points more directly to the fan assembly. An alarm that remains with a confirmed good fan requires inspection of the board seating and power-supply monitoring circuit.
2. Check for Foreign Material and Mechanical Obstruction
With the machine safely isolated and discharged, inspect the external radiator cooling fan and its guard.
Check for:
- Metal chips, wire fragments, cable ties, labels, or other foreign objects in the blade path
- Oil mist, dust, or sticky contamination that prevents free rotation
- A bent guard or deformed fan frame rubbing against the blades
- Cracked, missing, or distorted fan blades
- Fan wiring entering the blade path
- Loose screws that allow the housing or guard to contact the rotor
- Heavy contamination in the radiator fins that restricts airflow
Follow the approved inspection method for the exact fan unit. The blades should rotate freely without scraping, binding, bearing roughness, or excessive play. A fan that starts only when pushed, rotates slowly, stops intermittently, or makes abnormal bearing noise should be replaced even if removing debris temporarily clears the alarm.
Clean the fan and radiator only by the method permitted in the applicable documentation. Avoid forcing conductive dust, metal particles, or liquid deeper into the power-supply module.
3. Inspect the Fan Connector, Wiring, and Mounting
Check that the fan connector is installed in the correct socket and fully latched. Inspect the plug, contacts, wiring, and strain relief for:
- Partial insertion or a loose locking mechanism
- Bent, backed-out, corroded, or contaminated contacts
- Broken conductors near the connector
- Cut, pinched, heat-damaged, or oil-damaged insulation
- Incorrect wire routing after previous maintenance
- Loose connector-mounting, fan-motor, or metal-plate screws
The following illustration identifies typical fan-motor mounting screws, connector mounting screws, airflow direction, and fan positions used on several FANUC module widths. Use it as a location guide, then follow the drawing for the exact installed power-supply model.
Typical FANUC external radiator cooling-fan installation for 60/90 mm, 150 mm, and 300 mm module widths. Verify the exact arrangement for the installed power-supply model.
Do not tighten screws beyond the specified torque. Do not substitute a different connector position or route the wire where it can contact the blades or sharp metal edges.
4. Confirm the Control Printed-Circuit Board Is Fully Seated
FANUC identifies poor control printed-circuit-board installation as another possible cause of alarm A. On applicable designs, a loose connector between the control printed-circuit board and power printed-circuit board can interrupt the fan-monitoring circuit even when the fan itself is serviceable.
With power isolated and the DC link safely discharged:
- Check that the control printed-circuit board is installed correctly.
- Confirm that the faceplate is pushed fully into position where the design requires it.
- Inspect accessible board-to-board connections according to the applicable service procedure.
- Look for signs that the board was recently removed, replaced, or left partially engaged.
Do not push, remove, or reseat a printed-circuit board while the module is energized. Avoid touching electronic components or connector contacts unnecessarily, and observe the required electrostatic-discharge precautions.
5. Verify Fan Operation
After completing the de-energized inspection, reinstall all guards and restore the machine using the authorized test procedure. Observe the fan without exposing personnel to energized components.
Confirm whether the fan:
- Starts when required by the power-supply module
- Reaches a stable operating speed without hesitation
- Runs continuously rather than stopping intermittently
- Produces airflow in the specified direction
- Operates without bearing noise, vibration, or blade contact
- Maintains operation when the machine cabinet experiences normal vibration
A fan can rotate and still be defective. If its speed is too low or its monitoring output is unstable, the power supply may continue to report a cooling-fan alarm. Replace a slow, intermittent, or noisy fan rather than relying on a temporary restart.
6. Use a Known-Good Fan Only as a Controlled Test
If a new fan is not immediately available, a qualified technician may temporarily test with a confirmed good fan from an identical compatible module. The donor fan must match the original:
- FANUC or manufacturer part number
- Rated voltage and current
- Connector and wire positions
- Physical dimensions and mounting points
- Rotation and airflow direction
- Speed-monitoring or alarm-output arrangement
Do not exchange fans merely because their outside dimensions are similar. An electrically incompatible fan may fail to run, rotate in the wrong direction, provide an incorrect feedback signal, or damage the power-supply circuit.
If the alarm clears with the correct known-good fan, replace the original fan with the specified new part rather than returning the deteriorated fan to service.
7. Replace the External Radiator Cooling Fan
Replace the fan if it is seized, slow, noisy, physically damaged, electrically defective, or fails a controlled substitution test. Depending on the module width, replacement can require removal of a fan plate, connector-mounting screws, metal-plate screws, or fan-motor screws.
Before installing the replacement, verify:
- Complete fan or fan-unit part number
- Rated voltage, current, and connector pinout
- Speed-feedback or alarm-output configuration
- Mounting arrangement and screw type
- Airflow arrow and installation orientation
- Compatibility with the full power-supply model and suffix
Install the fan in the specified direction. A reversed fan can rotate normally yet provide insufficient cooling through the radiator. Secure the wiring so it cannot enter the blade path, touch hot surfaces, or rub against sharp edges.
If a replacement fan or power-supply module is required, browse FANUC servo, spindle, and power drives or send the complete power-supply and fan part numbers to REACO CNC for a compatibility check.
8. Check the Unit Stirring Fan on Applicable αiPS Models
FANUC B-65285EN/04 states that alarm A is also generated when the unit stirring fan stops on power-supply models A06B-6110-Hxxx and A06B-6120-Hxxx.
If the external radiator fan is operating normally and the installed power supply belongs to one of these model families:
- Identify the unit stirring fan using the model-specific maintenance drawing.
- Inspect it for obstruction, connector problems, damaged wiring, low speed, or mechanical failure.
- Confirm normal rotation under the authorized test procedure.
- Replace the unit stirring fan if it is defective.
Do not assume that every αiPS contains this additional fan or that every model monitors it through alarm A. Apply this branch only when the complete power-supply model and manual confirm it.
9. Evaluate the Power-Supply Module if the Alarm Remains
If both applicable fans operate correctly, the wiring and connectors are sound, and the control printed-circuit board is fully seated, the fan power or monitoring circuit inside the power supply may be abnormal.
At that point, arrange professional testing or replace the common power-supply module according to the machine-builder procedure. Before selecting a replacement, verify:
- Complete FANUC part number and every suffix
- Input-voltage class and rated capacity
- αiPS series and hardware specification
- Compatibility with all connected servo and spindle amplifiers
- Connector arrangement and cabinet installation
- Whether the fan unit transfers with the module or must be ordered separately
Do not install a replacement power supply with a seized, shorted, incorrectly wired, or incompatible fan. An unresolved external fan fault can reproduce the alarm or damage the replacement unit.
10. Retest the Cooling System
After correcting the obstruction, connector, wiring, fan, control-board seating, or power-supply fault, restore the machine according to the applicable procedure.
Confirm that:
- SV0606 and power-supply alarm A no longer appear
- The external radiator cooling fan starts and runs steadily
- The unit stirring fan operates normally on models that use one
- Airflow direction matches the installation drawing
- No abnormal noise, vibration, or blade contact is present
- Fan wiring is secured away from blades, hot surfaces, and sharp edges
- Cabinet filters, vents, and heat exchangers are not obstructed
- No subsequent converter, overheat, or communication alarm appears
Run the machine through the machine builder's required test cycle and monitor the power supply under normal load. If a different alarm appears, record and diagnose the new number independently.
Difference Between SV0601, SV0602, SV0603, and SV0606
| CNC alarm | Typical module display | FANUC description | Main distinction |
|---|---|---|---|
| SV0601 | F on an applicable servo amplifier | Inverter radiator cooling fan stopped | Concerns the servo-amplifier inverter fan |
| SV0602 | 6 on an applicable servo amplifier | Inverter overheat | Indicates excessive inverter temperature rather than only a stopped fan |
| SV0603 | 8., 9., or A., depending on axis channel | Inverter IPM overheat | Concerns the intelligent power module temperature |
| SV0606 | A on the applicable αiPS | Converter radiator cooling fan stopped | Concerns the common power-supply or converter fan |
The same cabinet can contain both SV0601-related and SV0606-related fans. Always use the CNC alarm number and the display on the physical module to identify the correct fan.
Difference Between SV0606 and SP9113
SV0606 and SP9113 can report the same converter cooling-fan condition through different CNC alarm paths.
| Alarm | Associated display | Meaning |
|---|---|---|
| SV0606 | A on the applicable power supply | Converter radiator cooling fan stopped, reported as a servo alarm |
| SP9113 | b3 / A on applicable spindle systems | Converter radiator cooling fan stopped, reported through the spindle alarm group |
Do not confuse either alarm with SP9088, which concerns the radiator fan associated with the spindle amplifier rather than the common power-supply module.
FANUC SV0606 Diagnostic Table
| Finding | Interpretation | Recommended action |
|---|---|---|
| CNC shows SV0606 and αiPS shows A | Power-supply radiator cooling fan fault is detected | Inspect the external radiator fan and its connector |
| Fan blades are obstructed | Foreign material or contamination is preventing rotation | Isolate power, remove the obstruction safely, inspect for damage, and retest |
| Fan connector is loose or partly inserted | Fan power or monitoring signal is interrupted | Inspect contacts and reconnect it fully with power isolated |
| Fan is noisy, slow, intermittent, or difficult to start | Fan bearings or motor are deteriorating | Replace the fan with the exact compatible part |
| Correct known-good fan clears the alarm | Original external fan is defective | Install the specified replacement fan |
| External fan runs normally on A06B-6110-Hxxx or A06B-6120-Hxxx | The monitored unit stirring fan may be stopped | Inspect and replace the unit stirring fan if defective |
| Alarm began after control-board work | Board or internal connector may be partly disengaged | Install the control board and faceplate fully according to the manual |
| Both fans and connections are normal but alarm remains | Power-supply fan drive or monitoring circuit may be abnormal | Professionally test or replace the common power-supply module |
| Module shows a code other than A | A different converter condition may be present | Diagnose the actual code using the exact model manual |
Recommended Troubleshooting Order
- Confirm SV0606 on the CNC and record the display on every amplifier and power-supply module.
- Record the complete common power-supply model, suffixes, and fan part number.
- Isolate power, observe the DC-link discharge time, and verify a safe condition.
- Inspect the external radiator fan for foreign material, oil, dust, blade damage, and mechanical obstruction.
- Inspect the fan connector, wiring, strain relief, guard, mounting screws, and radiator airflow path.
- Confirm the control printed-circuit board and faceplate are fully seated on applicable designs.
- Restore the machine safely and confirm fan speed, stability, and airflow direction.
- If necessary, test with an identical known-good compatible fan.
- Replace the defective external radiator cooling fan.
- On A06B-6110-Hxxx and A06B-6120-Hxxx models, inspect and replace the unit stirring fan if required.
- If the correct fans and connections are normal but SV0606 remains, professionally test or replace the common power-supply module.
- Retest under normal load and diagnose any new alarm separately.
Need Help With FANUC SV0606?
REACO CNC provides independent testing, repair, compatibility checking, and replacement support for FANUC power-supply modules, servo amplifiers, spindle amplifiers, and cooling-fan assemblies. Send us the CNC alarm screen, every module display, complete power-supply model and suffix, fan part number, and details of when the alarm occurs.
Visit the FANUC Technical Support Center for more FANUC alarm guides, or contact REACO CNC for assistance.
Reference Source: Beijing FANUC. This article is based on FANUC technical documentation. The exact fan, connector, board-seating, and replacement procedure depends on the installed power-supply model and machine.
