Servo Amplifier - Identification Guide

RD0095

Revision A - 03/2026

Introduction

The 30A and 40A servo amplifiers are available in two versions analog and digital. Although the two types perform similar functions, they are visually identical, which means you cannot distinguish them by appearance alone.

The only reliable way to tell them apart is by checking the part number.
This document explains where to locate the part number on the amplifier and how to use it to determine whether the unit is analog or digital.

Note: For servo amplifier replacement procedures and compatibility information, refer to the following document: Servo Amplifier - Replacement AD0280

30A Servo Amplifier

30A Analog Servo Amplifier

For the 30A Analog Servo Amplifier, the part number is located on the top of the amplifier housing.

Assembly Part Number:  32-5550X

Current Firmware: V1.32

30A Digital Servo Amplifier

For the 30A Digital Servo Amplifier, the part number is located on the top of the amplifier housing.

Assembly Part Number:  32-9118

Current Firmware: V2.32

40A Servo Amplifier

40A Analog Servo Amplifier

For the 40A Analog Servo Amplifier, the part number is located on the top of the amplifier housing.

Assembly Part Number:  32-3551X

Current Firmware: V1.32

40A Digital Servo Amplifier

For the 40A Digital Servo Amplifier, the part number is located on the top of the amplifier housing.

Assembly Part Number:  32-9119

Current Firmware: V2.32

12.1 Servo Amplifier Replacement

Servo Amplifier - Replacement

AD0280

Revision B - 03/2026

Introduction

This procedure tells you how to remove a servo amplifier and install a smart servo amplifier.

If you replace a servo amplifier that was made before 2007, refer to PCB Auxiliary (AUX) Load - Replacement.

Document Applies to these Parts

  • 93-32-5549       AMP, 90A BL SMART
  • 93-32-5550J      AMP, 30A BL SMART
  • 93-32-5550N    AMP, 30A BL SMART
  • 93-32-3551J       AMP, 45A BL SMART
  • 93-32-3551N     AMP, 45A BL SMART
  • 93-32-5552G     AMP, 60A BL SMART
  • 93-4988       AMP,  60A BL SMART
  • 93-4989       AMP,  90A BL SMART
  • 93-5088       AMP, 30A DIGITAL AMP
  • 93-5089       AMP, 45A DIGITAL AMP    

NOTE: The Digital Amplifiers are fully backward compatible with BL Smart Amplifiers.

NOTE: Refer to the Servo Amplifier - Identification Guide for more information. 

Electrical Safety

 DANGER: Working with the electrical services required for CNC machines is extremely hazardous and can result in serious injury or death.

Before connecting line wires to the CNC:

  • Turn off all power to the machine at the source.
  • Perform a Lockout-Tagout (LOTO) procedure to ensure the power remains off during service.
  • Verify that power has been disconnected by using an AC voltage detector on all incoming lines.

If you are uncertain about how to safely disconnect power or perform LOTO procedures:

  • Do not proceed.
  • Contact qualified personnel or obtain appropriate assistance before continuing.

Failure to follow these precautions may result in electrical shock, equipment damage, or fatal injury.

 Danger: Before beginning any work inside the control cabinet, verify that the High Voltage indicator light on the 320V Power Supply / Vector Drive has been off for a minimum of five (5) minutes. This waiting period ensures that residual voltage has dissipated and reduces the risk of electric shock.

Certain service procedures involve high-risk electrical components and may pose serious injury or fatality hazards. Technicians must not attempt any procedure unless they have a complete understanding of the steps involved and the associated risks.

If there is any uncertainty regarding a procedure, contact your Haas Factory Outlet (HFO) to arrange for a qualified service technician.

Replacement

1

Push [POWER OFF].

Set the main circuit breaker to the [OFF] position.

Lock the main circuit breaker. Use an approved lock with an approved safety tag.

Danger: If the voltage indicator light is on, do not touch the electrical components. The high voltage in the electrical cabinet can kill you. Wait for the voltage indicator LED to go off fully.

2

Disconnect the cables from the used servo amplifier. Remove the used servo amplifier.

Install the replacement smart servo amplifier [1].

Connect the current command [2] cable.

Connect the servo cables [3]. The cables are color-coded.

Connect the high-voltage jumpers [4] to the terminals on the adjacent servo amplifier.

12.1 Servo Amplifier Troubleshooting Guide

Servo Amplifier - Troubleshooting Guide - NGC

TG0125

Revision D - 6/2026

Introduction

There are four versions of Haas amplifiers. 30A [1], 45A [2], 60A [3], and 90A [4]. All four operate the same way.

Smart Amplifier assemblies are powered from the 320 VDC Bus from the Vector Drive assembly or Minimill Power Supply. They each have a red LED FAULT light, and a green LED POWER ON light to show the status of the amplifier.

Download and fillout the Amplifier Inspection Report Checklist below before replacing any parts.

Amplifier Inspection Report Checklist

Electrical Safety

 DANGER: Working with the electrical services required for CNC machines is extremely hazardous and can result in serious injury or death.

Before connecting line wires to the CNC:

  • Turn off all power to the machine at the source.
  • Perform a Lockout-Tagout (LOTO) procedure to ensure the power remains off during service.
  • Verify that power has been disconnected by using an AC voltage detector on all incoming lines.

If you are uncertain about how to safely disconnect power or perform LOTO procedures:

  • Do not proceed.
  • Contact qualified personnel or obtain appropriate assistance before continuing.

Failure to follow these precautions may result in electrical shock, equipment damage, or fatal injury.

 Danger: Before beginning any work inside the control cabinet, verify that the High Voltage indicator light on the 320V Power Supply / Vector Drive has been off for a minimum of five (5) minutes. This waiting period ensures that residual voltage has dissipated and reduces the risk of electric shock.

Certain service procedures involve high-risk electrical components and may pose serious injury or fatality hazards. Technicians must not attempt any procedure unless they have a complete understanding of the steps involved and the associated risks.

If there is any uncertainty regarding a procedure, contact your Haas Factory Outlet (HFO) to arrange for a qualified service technician.

Symptom Table

Symptom Possible Cause Corrective Action

Alarm 993 AMPLIFIER SHORT CIRCUIT and 1.993 - 11.993

Alarm 2040 VECTOR DRIVE OR SPINDLE AMPLIFIER-SHORT CIRCUIT

 Amplifier detected a short. Check cables for contamination or damage.
Refer to the service news HBC-N-03/17/25 for how to troubleshoot if the alarm intermittently occurs while the machine is running.
The amplifier has a internal short circuit. Do the Amplifier Short Circuit Inspection section.

Note: If a short-circuit is found, inspect the cable and motor for a short circuit before installing a new amplifier.
Terminal connections are not tight. Check that all terminal connections are tight and secure.
Alarm 986 CALIBRATION FAULT and 1.986 - 11.986 Amplifier internal calibration. Check the command cable from the Maincon PCB to amplifier. Check the 320 VDC voltage to amplifiers.
Alarm 986 CALIBRATION FAULT when first powering on machine. The  alarm requires the machine to have power cycled Amplifier internal calibration Refer to the service news HBC-N-03/17/25 for what to troubleshoot on the amplifier.
Alarm 992 AMPLIFIER OVER CURRENT and 1.992 - 11.992 Axis mechanical blockage. Axis mechanical blockage.
Alarm 994 AMPLIFIER OVER LOAD and 1.994 - 11.994 Incorrect application. Change speed and check for tool damage.
Axis mechanical blockage. Remove Blockage.
Alarm 991 AMPLIFIER OVER TEMPERATURE and 1.994 - 11.994 Problem with the cooling fan. Check cooling fan.
Alarm 1.9911 - 11.9911 Axis Amplifier Cable Disconnected The cable connected to the amp is damaged or disconnected Check that both ends of the cable going between the main processor and the servo amplifier are fully connected. Check the entire length of the cable to see if there is any damage.
The firmware on the amplifier is outdated If the alarm can be reset from the Haas Control, the amplifier needs to be replaced. If the alarm gets reset, he machine needs to be power cycled before running the machine again. Refer to the HBC-N-03/14/2025 for more details.

NGC machines equipped with a 60A servo amplifier

Alarm 3.991 Z-AXIS AMPLIFIER OVER TEMPERATURE.

 Erroneous alarm generated by electrical noise.

 

  • Install a ferrite filter P/N 64-1252 to the Z-axis motor power cables [2].
  • If the machine has the ferrite filter installed and the alarm persist replace the 60A servo amplifier with (P/N 93-32-5552F or later).
  • If the machine already has the 60A servo amplifier (P/N 93-32-5552F or later), check the amplifier for a overheat condition. Look at the servo fan for correct operation and the cutting application before changing any parts.

 
Alarm 4.9921 Velocity Error Too Large appears on a Tool Room Lathe 1/2.  Mis wired Spindle Amplifier.   See the TL Spindle Amplifier Inspection section below for the corrective action.
Axis instability, humming, vibration, or oscillation when installing a digital amplifier.  Compatibility issue between digital amplifiers and Size 02 and Size 04 servo motors. Refer to HSA-0083-04/13/2026 for the corrective action.

Mechanical Blockage

Corrective Action:

Make sure the axis has a clear path of travel. Tools, part fixtures, or workpieces that are too large can crash into the machine 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 are signs 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 Inspection

Check the amplifier for a short. Power off the machine. Disconnect the cables for the axis servo motor at the amplifier that generates the alarm.

Set the multimeter to ohms, and take the following reading:

  • Place the black lead on the ground screw [1].
  • Place the red lead on the RED terminal [2] and record the resistance reading.
  • Repeat this with the red lead on the WHT, BLK, HV(+), and HV(-) terminals and record the resistance reading for each.

Note: If the multimeter allows you to set the Ohms range, set it to the MegaOhms range.

If the multimeter does not show (O.L) for each of these readings then the amplifier is damaged.

Set the multimeter to ohms, and take the following reading:

  • Place the black lead on the HV (-) terminal [1].
  • Place the red lead on the RED terminal [2] and record the resistance reading.
  • Repeat this with the red lead on the WHT, and BLK terminals and record the resistance reading for each.

Note: If the multimeter allows you to set the Ohms range, set it to the MegaOhms range.

The multimeter should show a resistance in the MegaOhms range for each of these readings.

If the resistance reading is very low then the amplifier is damaged.

Set the multimeter to ohms, and take the following reading:

  • Place the black lead on the HV (+) terminal [1].
  • Place the red lead on the RED terminal [2] and record the resistance reading.
  • Repeat this with the red lead on the WHT, and BLK terminals and record the resistance reading for each.

Note: If the multimeter allows you to set the Ohms range, set it to the MegaOhms range.

The multimeter should show a resistance in the MegaOhms range for each of these readings.

If the resistance reading is very low then the amplifier is damaged.

Servo Motor Short Circuit Inspection

Corrective Action:

Check the cables for a short: Make sure the axis servo motor cables are not contaminated or pinched. Contaminated or pinched cables can cause a short. Replace the cables if necessary.

Inspect the servo motor. Disconnect and inspect the power cable connector at the motor. Make sure that there is no coolant contamination. Coolant contamination can cause this alarm and damage the amplifier. Measure the resistance from the pins labeled A, B and C at the motor connector to chassis ground.

  • The reading should show an open circuit.
  • If there is not open resistance, the servo motor is at fault.

Review the Part Program

Corrective 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 rate causes the alarm, then the servo amplifier is at fault.

Low Voltage Inspection

Corrective Action:

Measure the low voltage power supply voltage levels at the Maincon PCB. Make sure you 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 generates the alarm at the same time, and the low voltage power supply is correct, then the Maincon PCB may be at fault.

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:

 Note: The maximum temperature for safe operation of Haas CNC machines is 122 °F (50 °C). The amplifier over temperature sensor will trigger at 195 °F (90 °C).

Make sure the cooling fan for the servo amplifiers operates correctly.

If the fan does not operate correctly, measure the voltage it receives. Disconnect the cable from the cooling fan. Measure the voltage between the leads of the cable. The correct voltage 120 VAC.

  • If the cable has the correct voltage, the cooling fan is defective.

TL 1/2 Spindle Amplifier Inspection

Corrective Action:

Open the electrical control of the machine and inspect the phasing of the spindle amplifier.

Note: Refer to the image to verify the correct phasing between the spindle motor and spindle amplifier on a Toolroom Lathe 1/2.

Electrical Diagram