Cooling fan
Common VFD, drive, UPS, and cabinet overheating failure point.
Mazak Nexus Series Error Codes
Mazak Nexus series (QTN, QT, VCN, VCS, HCN) machines use the Mazatrol MATRIX CNC or SMOOTHG control. Alarms display on the CNC screen with a number and description. Alarms are grouped by category: 1xx (servo), 2xx (spindle), 3xx (PC/control), 4xx (OT/limit), 5xx (ATC/APC), 6xx (chuck/tailstock).
Nexus Alarm Code Table
| Code | Fault Description | Common Cause | Action |
|---|---|---|---|
| 50 | Emergency stop | E-stop activated | Release and check cause |
| 100 | Servo alarm - X axis | Servo drive or motor fault | Check servo drive |
| 200 | Spindle alarm | Spindle drive fault | Check spindle drive |
| 201 | Spindle overspeed | Speed above maximum | Check program S code |
| 300 | Control unit alarm | NC/PC communication fault | Check PC board |
| 400 | Overtravel - positive | Axis past positive limit | Move axis, check limits |
| 401 | Overtravel - negative | Axis past negative limit | Move axis, check limits |
| 500 | ATC alarm | Tool changer fault | Check ATC sequence |
| 501 | Magazine alarm | Magazine positioning fault | Check magazine servo |
| 600 | Chuck fault | Chuck not clamped | Check hydraulic pressure |
| 601 | Tailstock fault | Tailstock positioning fault | Check tailstock control |
| 700 | MPC alarm | Machine parameter error | Check machine parameters |
| 800 | ATC carrier alarm | Carrier positioning fault | Check carrier servo |
Most Common Nexus Faults
100/200 - Servo/Spindle Alarms
Nexus servo alarms refer to the Mazak servo pack (FANUC-based). Check servo amplifier LED on cabinet door. Alarm LED codes: 1 = overload, 2 = regeneration, 3 = DC bus, 4 = IGBT, 5 = feedback, 6 = communication. Match LED reading to specific remediation.
400/401 - Overtravel
Work offset or tool offset entered incorrectly. In MDI mode with E-stop released, hold SHIFT + override axis in JOG mode to move axis back into travel range. Then review all offsets before resuming production.
500 - ATC Alarm
Mazak Nexus ATC sequence is programmable. Check which step in the M6 sequence fails - view ATC sequence diagram in the machine maintenance screen. Common causes: proximity switch failure, servo positioning error, or mechanical jam.
600 - Chuck Fault
Check hydraulic pressure (minimum 900 PSI for standard chucks). Verify workpiece is seated correctly. If chuck relay is suspected, check PLC input in the Mazatrol diagnostic screen.
Parts Commonly Needed
| Part | Notes |
|---|---|
| Servo pack | Match axis and current rating |
| Encoder battery | Absolute encoder backup |
| ATC proximity switches | Check position in sequence diagram |
| Hydraulic pressure switch | Chuck and tailstock circuits |
| Coolant pump | Check impeller and motor amps |
Technician Tips
CNC alarms should always be diagnosed by reading the full alarm text, not just the number. Modern Fanuc, Haas, and Mazak controls provide detailed alarm descriptions — press the help key while viewing the alarm for diagnostic suggestions. The alarm history screen stores the last 50-100 alarms with timestamps; review this before clearing to identify patterns. A servo alarm (SV series on Fanuc) that appears only during rapid traverse points to a different cause than one that appears during cutting.
Prevention: Back up your CNC parameters monthly. Battery-backed memory faults are much easier to recover when you have a current parameter, ladder, offset, and macro backup. Replace control batteries on a planned maintenance schedule before voltage drops far enough to risk data loss.
Need Replacement Parts?
Before ordering, match the machine-control part to the model number, electrical rating, and failure symptom. Check current prices on Amazon - prices and availability change frequently.
Pro tip: Mazak Nexus stores alarm history with timestamps in the ALARM LOG menu. Access via MAINTENANCE -> ALARM LOG. Historical data shows if an alarm is intermittent (temperature-related) or consistent (mechanical or electrical failure).