What causes Haas alarm 39?

Electrical cabinet cooling fans have failed or are running at reduced speed due to capacitor failure or worn bearings causing insufficient airflow across servo amplifier heatsinks. Servo amplifier heatsink is clogged with dust, metal chips, or coolant mist residue blocking thermal transfer from power components to cooling air. Air intake filters are severely restricted with accumulated dirt preventing adequate cooling air from entering electrical cabinet and reaching servo amps. Servo amplifier is working excessively hard due to mechanical binding on axis, bad ballscrew, tight gibs, or improper tuning causing high continuous current draw and heat buildup. Ambient temperature around machine or inside electrical cabinet exceeds design limits (over 104-110°F) reducing thermal margin and causing premature overtemperature faults.

How do I fix Haas alarm 39?

1. Step 1: Allow servo amplifiers to cool for minimum 20-30 minutes, verify all electrical cabinet cooling fans are operating at full speed and replace any failed or slow-running fans 2. Step 2: Remove and clean or replace all electrical cabinet air filters, ensure cabinet air intake and exhaust paths are completely unobstructed 3. Step 3: Open electrical cabinet and use compressed air to blow out servo amplifier heatsinks and surrounding area, removing all dust and debris from cooling fins 4. Step 4: Check Diagnostics page for servo amplifier temperatures and motor current draw on all axes during jogging to identify if one axis is drawing abnormally high current indicating mechanical issue 5. Step 5: Manually move affected axis through full travel with servo off to check for binding, rough spots, or excessive drag that would cause servo to work harder and generate more heat 6. Step 6: If cooling system is clean and functional but alarm persists, check servo tuning parameters (gains, especially velocity and acceleration) for proper values; if mechanical and tuning are correct, servo amplifier may have degraded components requiring replacement

Haas codes

axismd.ai

Haas Controller

Overheat/Thermal · Basic · 30-60 minutes

Alarm 39

HAAS Alarm 39 - Axis Drive Amplifier Overheat

Alarm 39 fires when the servo drive amplifier temperature sensor exceeds the thermal shutdown threshold, typically 85°C. The NGC control monitors drive temperatures continuously and triggers this alarm to prevent permanent damage to the servo amplifier electronics.

HaasOverheat/ThermalBasic30-60 minutes

39

HAAS Alarm 39 - Axis Drive Amplifier Overheat

Axis servo amplifier temperature too high

This alarm is generated when one or more axis servo amplifier modules exceed their internal temperature limit as measured by thermistors monitoring the power components. The affected servo amp will disable immediately to protect IGBTs and other heat-sensitive components from thermal failure. The MOCON board receives this fault condition from the servo amplifier and halts all axis motion, displaying which axis amplifier has overheated in the alarm message.

Root Cause Summary

Safety

Do not touch the servo drive heatsink or housing while it is hot; thermal burns can result from contact
Do not restart axis motion until the servo drive has cooled for at least 15 minutes to prevent immediate re-alarm
Disconnect power from the servo drive circuit before performing cleaning or internal inspection

Causes and Fixes

1
Power down and lockout machine
Turn main disconnect OFF and follow LOTO procedures before opening electrical cabinet.
High voltage present - ensure power is OFF before proceeding
2
Inspect servo drive cooling fins
Open electrical cabinet and visually inspect all axis servo drives for dust buildup on heat sink fins and cooling passages.
Use flashlight to check between fins - buildup often hidden in narrow spaces
3
Clean cooling system
Use compressed air (max 30 PSI) to blow out cooling fins, cabinet fans, and air filters. Clean from inside-out to avoid pushing debris deeper.
Wear safety glasses and ensure all loose debris is removed from cabinet
4
Check cabinet ventilation
Verify cabinet cooling fans operate properly and air filters are clean. Replace filters if heavily contaminated.
Cabinet should maintain slight positive pressure to prevent dust ingress

DIY Feasiblehigh confidence

Call a technician if:

·Drive LED indicates internal fault
·Temperature alarm persists after cleaning and mechanical checks
·Multiple axes showing thermal issues simultaneously
·Suspected servo drive component failure

Prevention

Clean cabinet filters monthly
Monitor Parameter 19 axis loads regularly
Maintain shop temperature below 40°C
Schedule regular way lubrication
Avoid continuous high-speed operation without cool-down periods

Common Mistakes

Ignoring gradual temperature buildup
Using excessive air pressure when cleaning (damages components)
Not checking mechanical binding before assuming drive failure
Operating machine immediately after cleaning without allowing drives to reach normal temperature

Related Alarms

31 32 33 34 35 36

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