In automated production lines, the servo cabinet is the core of high‑precision motion control. When it malfunctions, the entire line can stop, causing significant production losses. Based on years of field service experience, we have developed a practical, easy‑to‑follow troubleshooting approach to help maintenance teams quickly pinpoint issues and restore operation.
Step 1: No Power Response – Check the Source
Symptom: The cabinet shows no reaction after power‑on – indicators are off, fans do not spin.
Don’t rush to open the cabinet. Follow these three checks first:
1. Inspect the external main power supply
Use a multimeter to confirm that the three‑phase voltage is within rated limits.
Verify that the main circuit breaker and fuses have not tripped or blown due to overload.
2. Check the 24 V DC control power
Measure the output of the auxiliary power supply inside the cabinet. In many cases, a failed auxiliary supply is the only reason the entire system fails to start.
3. Confirm the emergency stop button
Make sure the E‑stop is not pressed or locked. Often, a simple reset restores normal operation.
Pro tip: Our cabinets are factory‑tested with at least three load tests on the power circuit, and each door includes a clear power flow diagram – making first‑line checks much easier.
Step 2: Motor Does Not Run – Verify the Signal Chain
Symptom: The cabinet powers up normally, but the motor does not move when a run command is issued.
Prioritise the command path:
Read the drive display – Look for alarm codes such as AL01 (overcurrent) or AL03 (overvoltage). These immediately narrow down the possible causes; refer to the drive manual for specific actions.
Check the command signals – Use an oscilloscope or the PLC monitoring function to confirm that pulse/direction signals from the PLC or host controller are actually reaching the drive’s signal terminals.
Verify the enable signal – Many operators forget that the servo enable must be active. Without it, the drive remains in standby/locked state.
Pro tip: We deliberately place test points at all critical signal nodes in our cabinet designs. Maintenance staff can measure signal continuity without disconnecting any wires, improving troubleshooting efficiency by over 60%.
Step 3: Vibration, Noise, or Poor Accuracy – Check Mechanics and Parameters
Symptom: The motor vibrates noticeably, makes abnormal noise, or machining precision drifts.
Do not assume motor damage immediately – 80% of such cases can be resolved quickly:
1. Run the motor uncoupled from the load
If vibration persists without load, the likely cause is mismatched servo gain settings. Try reducing the position‑loop and velocity‑loop gains moderately to stabilise the response.
2. If vibration occurs only under load
Inspect mechanical couplings for looseness.
Check for excessive backlash in the transmission. Many on‑site noises are simply resonance caused by mechanical play.
3. Examine the encoder feedback path
Ensure the encoder cable is properly shielded and connectors are tight. Signal interference can corrupt position feedback and cause erratic motion.
Pro tip: Our cabinets come with pre‑tuned base gain parameters tailored to the typical load type of your application. On arrival, only fine‑tuning is needed for stable operation, greatly reducing commissioning time.
Step 4: Frequent Alarms or Random Restarts – Focus on Cooling and Load
Symptom: The drive triggers overtemperature or overload alarms intermittently, or the cabinet reboots without warning.
These elusive faults can be traced with this systematic approach:
1.Check cabinet cooling
Clean the dust filters and verify that the cooling fans are running properly. In hot weather, poor ventilation is the number one cause of overtemperature alarms.
2.Monitor the drive load curve
If the load rate consistently exceeds 90%, look for mechanical binding or jamming in the driven equipment. Prolonged overload can permanently damage the drive.
3.Inspect power and grounding cables
Look for worn, cracked, or loose connections. Poor grounding can introduce electrical noise, leading to random alarms and reboots.
At Huadong industry Control, we believe that a good servo cabinet should not only perform reliably but also be easy to operate and maintain. Mastering these four steps reduces dependency on external support and significantly improves overall line efficiency. For complex or unusual faults, our technical service team is ready to respond promptly – keeping your production running smoothly.
