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LAST UPDATED: 01/21/2019
LAST UPDATED: 01/21/2019
Servo Amplifier - Troubleshooting Guide
Introduction
Electrical Safety
Caution: When you do maintenance or repair on CNC machines and their components, you must always followbasic safety precautions. This decreases the risk of injury and mechanical damage.
• Set the main circuit breaker to the [OFF] position.
Danger: Before beginning any work inside the control cabinet the High Voltage indicator light on the 320V PowerSupply / Vector Drive must have been off for at least 5 minutes.
Some service procedures can be dangerous or life-threatening. DO NOT attempt a procedure that you do not fullyunderstand. If you have any doubts about doing a procedure contact your Haas Factory Outlet (HFO) and schedule aservice visit.
There are four versions of Haas amplifiers. 30A[1], 45A [2], 60A [3], and 90A [4]. All four operatethe same way.
Smart Amplifier assemblies are powered fromthe 320 VDC Bus from the Vector Drive assemblyor Minimill Power Supply. They each have a redLED FAULT light, and a green LED POWER ONlight to show the status of the amplifier.
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Symptom Table
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Symptom Possible Cause Corrective Action
Amplifier detected ashort. Check cables for contamination or damage.Alarms 161-164 AXIS
DRIVE FAULT,
Alarm 993 AMPLIFIERSHORT CIRCUITand 1.993 - 6.993
Alarm 2040 VECTORDRIVE OR SPINDLEAMPLIFIER-SHORTCIRCUIT
The amplifier has ainternal short circuit.
Do the Amplifier Short Circuit Inspection section.Note: If a short-circuit is found, inspect the cable and motorfor a short circuit before installing a new amplifier.
Alarms 161-164 AXISDRIVE FAULT andAlarm 986 CALIBRATIONFAULT
Amplifier internalcalibration.
Check the command cable from the Maincon / Mocon PCB toamplifier. Check the 320 VDC voltage to amplifiers.
Alarms 161-164 AXISDRIVE FAULT andAlarm 992 AMPLIFIEROVER CURRENT
Axis mechanicalblockage. Axis mechanical blockage.
Incorrect application. Change speed and check for tool damage.Alarms 161-164 AXISDRIVE FAULT andAlarm 994 AMPLIFIEROVER LOAD
Axis mechanicalblockage. Remove Blockage.
Alarms 161-164 AXISDRIVE FAULT andAlarm 991 AMPLIFIEROVER TEMPERATURE
Problem with thecooling fan. Check cooling fan.
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NGC machinesequipped with a 60Aservo amplifier
Alarm 3.991 Z-AXISAMPLIFIER OVERTEMPERATURE.
Erroneous alarmgenerated by electricalnoise.
• Install a ferrite filter P/N 64-1252 to the Z-axis motorpower cables [2].
• If the machine has the ferrite filter installed and thealarm persist replace the 60A servo amplifier with (P/N93-32-5552F or later).
• If the machine already has the 60A servo amplifier (P/N93-32-5552F or later), check the amplifier for a overheatcondition. Look at the servo fan for correct operationand the cutting application before changing any parts.
Alarm 991 AMPLIFIEROVER TEMPERATURE.
The Maincon/Moconaxis channel isdefective, or there is abroken pin on theconnector.
Remove the encoder/drive cables from the Maincon/Mocon PCBaxis channel. Inspect the connectors pins. Test the axis on adifferent Maincon/Mocon channel, if the problem goes away thereis a problem with the axis channel.
Mechanical BlockageCorrective Action:
Make sure the axis has a clear path of travel. Tools, part fixtures, or workpieces that are too large can crash into themachine enclosure.
Look at the machine's alarm history. Overload alarms followed by over current alarms are a sign of a crash.
Look at the machine enclosure, spindle and tooling for damage. Damage to the tooling, fixtures and enclosure aresigns of a crash.
If there are no signs of a crash, inspect the ballscrew and linear guides. They must move or turn freely by hand.
Amplifier Short Circuit InspectionCheck the amplifier for a short. Power off the machine. Disconnect the cables for the axis servo motor at the amplifierthat generates the alarm.
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Place MultiMeter Leads Here Instructions
Set the meterto ohms, andtake thefollowingreadings:
Groundscrew to RED,WHT, andBLKterminals
If the meterdoes notshow open(o.l) theamplifier isdamaged.
Set the meterto Ohms, andtake thefollowingreadings:
Black lead onHV (+) andRed lead toHV (-), RED,WHT, andBLKterminals.
The metershould showhighresistancereadingstypically inthe Kilo orMega ohms.If the meterreads verylowresistancethe amplifieris damaged.
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Set the meterto diode testmode, andtake thefollowingreadings:
Red lead onHV (-) andblack lead toHV (+), RED,WHT, andBLKterminals
If the meterdoes notshow avoltage dropranging from0.2 to 0.8volts theamplifier isdamaged.
Set the meterto diode testmode, andtake thefollowingreadings:
Black lead onHV (-) and redlead to HV(+), RED,WHT, andBLKterminals
If the meterdoes not anopen circuit(O.L) theamplifier isdamaged.
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Servo Motor Short Circuit Inspection
Review the Part ProgramCorrective Action:
The machine load is too high. Decrease the feeds to decrease the machine load. Examine the cutting tool for damage.
Test the axis that generates the alarm. Write a program in MDI to move the axis. If any movement at any feed ratecauses the alarm, then the servo amplifier is at fault.
Corrective Action:
Check the cables for a short: Make sure the axisservo motor cables are not contaminated orpinched. Contaminated or pinched cables cancause a short. Replace the cables if necessary.
Inspect the servo motor. Disconnect and inspectthe power cable connector at the motor. Makesure that there is no coolant contamination.Coolant contamination can cause this alarm anddamage the amplifier. Measure the resistancefrom the pins labeled A, B and C at the motorconnector to chassis ground.
• The reading should show an opencircuit.
• If there is not open resistance, the servomotor is at fault.
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Low Voltage Inspection
Pins Correct Voltage
+5 and GND +4.90 to +5.20 V dc
+12 and GND +11.85 to +12.50 V dc
-12 and GND -11.85 to -12.50 V dc
Cooling Fan
Corrective Action:
Measure the low voltage power supply voltagelevels at the Maincon or Mocon PCB. Make sureyou do not short or cross your multimeter pins.
Cycle power to the machine. If the fault stays,then the amplifier is faulty.
If every axis amplifier in the machine generatesthe alarm at the same time, and the low voltagepower supply is correct, then the Maincon orMocon PCB may be at fault.
Corrective Action:
Note: The maximum temperature for safeoperation of Haas CNC machines is 122 °F (50 °C).The amplifier over temperature sensor will triggerat 195 °F (90 °C).
Make sure the cooling fan for the servo amplifiersoperates correctly.
If the fan does not operate correctly, measure thevoltage it receives. Disconnect the cable from thecooling fan. Measure the voltage between theleads of the cable. The correct voltage 120 VAC.
• If the cable has the correct voltage, thecooling fan is defective.
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Electrical Diagram
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