Service Home H-5AX Double Yoke Spindle Head - Troubleshooting Guide - TG0068
Last updated: 04/29/2026

H-5AX Double Yoke Spindle Head - Troubleshooting Guide

TG0068

Revision D - 12/2025

Introduction

Important: Download and fill out the Spindle Inspection Report Checklist and the latest Inspection Report below before replacing any parts.

Warning: The machine should be stopped and powered off immediately is signs of coolant or chiller fluid is seen leaking from between the spindle and spindle mount plate.

Warning:  Breaking the DON'T REMOVE seal on the spindle without contacting Haas Service will VOID the warranty. Contact Haas Service before proceeding with any adjustments.

Note: This procedure only applies to the H-5AX Double Yoke Spindle Head.

H-5AX Service Request Form
Inspection Report

This page will assist you in troubleshooting the H-5AX Double Yoke Spindle Head found on the VR series machines.

Symptoms Table

Symptom

Probable Cause

Solution
Alarm 130 Tool Unclamp Tool Holder is not properly seated in the taper Verify double arm alignment to the spindle, refer to Side-Mount Tool Changer - HSK - Double Arm - Replacement - NGC.
 Head Alignment Fill out the EA0449 VR Series Double Yoke Inspection Report.
 A63 Tool Holder orientation Refer to the HSK tool loading section in the HSK - Spindle - Troubleshooting Guide.
Air Pressure

Verify that the TRP pressure is set to 145 PSI in the lube panel cabinet. Verify that the Spindle Purge pressure is set to 45 PSI.

Verify customer’s air lines are not contaminated (moisture).
Draw Bar push out / switch adjustment Verify the clamping cone push out before adjusting TRP sensors. See H-5AX TRP Sensor Wiring section for images.
Alarm 134 Tool Unclamp Fault Spindle Air Solenoid has the .040 ORIFICE installed in the wrong location

Reconfigure the Air Solenoid fitting, Move the restrictor orifice from before 90° fitting to before the Tee Brass fitting. (see Spindle Air Solenoid).

Note: No parts required for corrective action.

HSG-A 02/16/2023

Tool Sticking in the Taper

Incorrect push out

Air escaping from the Air Regulator Knob
Spindle was replaced and spindle load is very high. Commanded RPM are incorrect as well. Motor may have been wired incorrectly during replacement. 

Check the motor configuration to see if the motor is wired correctly. See Motor Wiring section for more details.

If the spindle was not replaced and the machine is experiencing this issue please follow the VECTOR DRIVE TROUBLESHOOTING GUIDE for further troubleshooting.
Spindle noise is present while running the spindle at lower RPM's.  Damaged cables or missing ferrite filters can cause this issue. 

Troubleshoot the vector drive using the VECTOR DRIVE TROUBLESHOOTING GUIDE.

  • Verify all feedback cables at the maincon have ferrite filters
  • Verify cables in the spindle are in good condition (see Connection port section for more details.
  • Verify the spindle power cable is tight.
  • Verify all connections to the signal distribution junction are tight. See Connection Locations section for reference.

If the issue persists contact Haas Service for further instructions. 
Alarm 4.9003 Insuficient Spindle Coolant Chiller Flow Flow sensor on the spindle chiller may need to be adjusted to read correct flow.  Adjust the flow sensor using the slotted holes on the sensor, move the sensor towards the motor side until the bit changes. The slots on the sensor might not be enough adjustment, if so open the slots further to get the adjustment needed. Contact Haas Service if this issue continues to persist. 
Air may be introduced into the system via chiller lines not being fully plugged into the fittings or seals that are broken and sucking in air.  Replace any broken seals and make sure the lines are fully plugged into the fittings. Prime the lines and make sure the no air bubbles are present in the lines. 
Coolant tank chiller issues with less than normal pressure or an over-heated pump.

The correct placement of the 3” return tube. 

A 6’’ tube (58-3728) being used rather than the 3” tube (58-0742). The 6” tube was bottoming out and cause a major flow restriction. See VR/GM Spindle Heat Exchanger Tank section for images
Alarm 4.103  S (SPINDLE) AXIS SERVO ERROR TOO LARGE Encoder or encoder cable failure.  Verify the spindle encoder or encoder cable is not shorted to ground. See Encoder Connection section for more details.
Alarm 4.9932  S (SPINDLE) SPINDLE STALLED 
Alarm 4.9922  S (SPINDLE) MOTION CHANNEL FAULT DETECTED 
Alarm 4.224  S (SPINDLE) AXIS TRANSTION FAULT
Alarm 7.217 C (5th AXIS) AXIS PHASING ERROR
Alarm 7.9959 C (5th AXIS) SERIAL ENCODER DISCONNECT
Control showing 1000 rpms on the spindle speed with the spindle stopped.
Alarm 4.182  S (SPINDLE) AXIS ENCODER CABLE FAULT M23 Barrel may need to be adjusted to make a better connection. See M23 Barrel Connectors section below.
Encoder or encoder cable failure.  Verify the spindle encoder or encoder cable is not shorted to ground. See Encoder Connection section for more details.
Alarm 4.9975 S (SPINDLE) MOTOR TEMPERATURE CRITICAL OVERHEAT M23 Barrel may need to be adjusted to make a better connection. See M23 Barrel Connectors section below.
Alarm 6.103  B (4TH Axis) AXIS SERVO ERROR TOO LARGE

Brake does not disengage before commanding a movement resulting in high loads on the axis.

Brake air hoses are not connected properly.

Check the brake manifold and make sure the air lines are routed to the correct port. See B-Axis and C-Axis Brake Assembly section for more details. 

Verify parameter 76 Low Air Pressure Delay has not been changed (30.000 sec) and verify proper air to machine. 
Alarm 7.103  C (5TH Axis) AXIS SERVO ERROR TOO LARGE

Alarm 6.9720, 7.9720 B or C AXIS SECONDARY SERIAL ENCODER ALARM

Alarm Subcode (0x1) Encoder Data Fault

Scale signals are affected by noise from high power cables.

(Faulty Linear Scale, Configuration File issue; incorrect motor type or incorrect Scale type.)

Refer to Serial Data Communication Faults / Electrical Noise section below.

(Check Scale Encoder for coolant contamination.)

Alarm 6.9720, 7.9720 B or C AXIS SECONDARY SERIAL ENCODER ALARM

Alarm Subcode (0x2) Encoder Internal Axis Fault 1

 (The motion channel has reported an internal fault of a type that is not recognized by the control)  Cycle power to the machine. If the issue persists, take an error report (Shift F3) and email Haas Service

Alarm 6.9720, 7.9720 B or C AXIS SECONDARY SERIAL ENCODER ALARM

Alarm Subcode (0x3) Encoder Internal Axis Fault 2

  (Software has reported an internal fault of a type that is not recognized by the control.) Cycle power to the machine. If the issue persists, take an error report (Shift F3) and email to Haas Service

Alarm 6.9720, 7.9720 B or C AXIS SECONDARY SERIAL ENCODER ALARM

Alarm Subcode (0x4) Encoder CRC Fault

 (Linear Scale signals are affected by noise from high power cables.) (Refer to Serial Data Communication Faults / Electrical Noise section below.)

Alarm 6.9720, 7.9720 B or C AXIS SECONDARY SERIAL ENCODER ALARM

Alarm Subcode (0x5) Encoder Cable Fault

 (Cables are not connected correctly or Linear scale is faulty.) (Inspect the cables and connectors. Refer to the Main Processor/Encoder Cable section below.)
Low coolant pressure Too many coolant nozzles in use. Reduce the number of coolant nozzles to two. Verify all extra nozzle ports are plugged.
Wrong coolant option. It is recommended to use a High Pressure Flood Coolant (HPFC) on VR Double Yoke machines.  
Spindle Chiller fluid leaking between spindle cartridge and spindle mount plate. Machine crashed. Warning: The machine should be stopped and powered off immediately if signs of coolant or chiller fluid is seen leaking from between the spindle and spindle mount plate.

The spindle cartridge needs to be replaced. See H-5AX Double Yoke Spindle Head - Replacement - AD0743 for part number and how to replace the spindle head.
Alarm 9804 240VAC GROUND FAULT

HDC-3-5AX Machines built before 12/17/2024 only.

Stranding on the conductors pierces through the spindle power cable jacket overtime, making contact with the braided shield.

Replace the spindle power cable.

For HDC-3-5AX Machines built before 8/27/2024 order PN: 33-1304A

For HDC-3-5AX Machines built after 8/27/2024 and before 12/17/2024 order PN: 33-1455A

B-Axis and C-Axis Brake Assembly

1

To access the B-Axis brake air manifold rotate the C-Axis to C = 180 [1] and remove the B-Axis cover [2]. 

Verify the brake air line routing is correct.

[3] Brake Air Pressure Sensor

[4] Brake Unclamp 

[5] Brake Clamp

2

To access the C-Axis assembly remove the spindle head sheet metal [1]. 

Verify the brake air line routing is correct.

[2] Brake Clamp

[3] Brake Unclamp

[4] Brake Air Pressure Sensor

3

Check the B and C-Axis brake solenoid air lines in the CALM cabinet. 

Verify the brake air line routing is correct compared to the CALM cabinet decal.

Spindle Head Connections

Note: Decal version 29-1071B and lower contains the Single Yoke Spindle Head Connections only. Refer to the information below for the Double Yoke Spindle Head Connections. 

Connect the hoses from the spindle head to the hoses from the CALM Cabinet using the table below.

The Polyethylene (PE) hoses from the spindle head [1, 2, 8, 9] will have push-to-connect fittings.

The Polyurethane (PU) hoses from the spindle head [3, 4, 5, 6, 7] will have compression fittings.

 Note: The TRP hose [7] connects to the 3/8 black hose with the 3/8F NPT 1/4M compression fitting [10].

 

Haas Double Yoke (Before 5/9/2025)
  Head Hose Color     Head Hose Material Zip tie      CALM Hose Color      CALM Hose Material       Zip tie      
Clamp B-Axis     Opaque [2] PE None Opaque PE None
Release B-Axis Blue [8] PE None Blue PE None
Clamp C-Axis Black [9] PE None Black PE None
Release C-Axis Orange [1] PE None Orange PE None
TRP Black [7] PU Black Black PU Black
Taper Pressure Clear [6] PU None Clear PU None
Electrospindle coolant Black [3] PU Green Opaque PE Green
Electrospindle coolant Black [5] PU Green Opaque PE Green
Flood coolant Blue [4] PU Blue Blue PU inner braid Blue
Haas Double Yoke with Chiller (90° Swivel After 5/9/2025)
  Head Hose Color     Head Hose Material Zip tie      CALM Hose Color      CALM Hose Material       Zip tie      
Clamp B-Axis     Opaque [2] PE None Opaque PE None
Release B-Axis Blue [8] PE None Blue PE None
Clamp C-Axis Black [9] PE None Black PE None
Release C-Axis Orange [1] PE None Orange PE None
TRP Black [7] PU Black Black PU Black
Taper Pressure Clear [6] PU None Clear PU None
Electrospindle coolant Black [3] PU Green Opaque PE Green
Electrospindle coolant Black [5] PU Green Opaque PE Green
Flood coolant Black [4] PU Blue Blue PU inner braid Blue

Motor Wiring

1

Check the motor wirings and make sure they are wired in the delta configuration [1] shown in the image.

The barrel connector going to the vector drive [2] is also provided to ensure the cable is pinned correctly.

[3] - W1/V2
[4] - V1/U2
[5] - U1/W2
[6] - GROUND
[7] - C/W
[8] - B/V
[9] - A/U
[10] - GROUND

H-5AX TRP Sensor Wiring

1

Verify Spindle Clamping Collet push out is correct and all TRP sensor are properly adjusted.

Check the barrel connectors are tight and the connector at P2 on the 5AX Interface PCB is seated correctly.

(1) TRP Sensors

(2)  Spindle Head Inputs

(3)  5AX Interface PCB

Identifying the sensors for ES779 and ES789

S1+S4 - Clamping cone locked in the correct position (DRAWBAR CLOSED)

S2  - Clamping cone open tool-holder ejected, Draw Bar forward (DRAWBAR OPEN) 

S3 - Not Used

S5** - TRP backward at upper end stop (TRP PISTION RETRACTED) in series with S4 (DRAWBAR CLOSED)

** Present in certain versions only.

VR/GM Spindle Heat Exchanger Tank

1

The 6” return tube is bottoming out and cause a major flow restriction.

2

Corrective Action:  Install a 3" return tube (58-0742)

Encoder Connection

1

Test to see if the encoder is shorted to ground.

Using a multimeter, check continuity between the barrel connector case to spindle nose and pins to spindle nose.

Results should be continuity of 0.2 ohms at the barrel connector case to the spindle nose and all pins open to the spindle nose.

2

Test to see if the encoder cable is shorted to ground.

If results show continuity between the pins and spindle nose, open the Encoder inspection window on the side of the ES779 or ES789 spindle body and disconnect the encoder terminals.

Recheck for continuity between the pins of the barrel connector to the encoder connectors.  

Connector 3 pin 3 should be the only lead Closed to the Barrel Case showing 0.2 ohms and pin to pin should not be open.

3

Testing if the encoder is shorted to ground.

Using a multi meter, verify the pins are open to the Encoder Body. Connector 3 pin 3 should be the only pin closed to the encoder body showing 0.2 ohms. If any of the other pins show continuity, the encoder is shorted internally and will need to be replaced. 

It should also be noted if the encoder passes this test, this does not mean that the encoder is functioning properly, only that it is not shorted internally.

NOTE: Some encoder have a separate ground cable that is secured to the encoder 

For encoder replacement procedure refer to AD0558 GM / VR H-5AX Spindle Shaft - Replacement Guide  

H-5AX Spindle Chiller Fluid

VR and GM machines built before 5/9/2025 are equipped with the VR/GM Spindle Heat Exchanger and use a 50/50 mix of DOWFROST HD INHIBITED PROPYLENE GLYCOL (Not Sold by Haas) and deionized water. The tank capacity is 5 gallons. Any over the counter Propylene Glycol product can be used, but will require to flush out the system prior to filling. 

IMPORTANT: Mix the glycol and deionized water outside of the chiller tank before adding to the mixture already in the tank.

Warning:  Don’t mix with Ethylene-glycol product. If Ethylene-glycol is the only substitute to be found then the system must be flushed prior to filling.

Warning: Do not mix the glycol product with anything other than deionized water.

VR and GM machines built from 5/9/2025 and after are equipped with the VR/GM Spindle Chiller and use Mobil Velocite Oil No 3 (PN: 93-4894). For more information on the VR/GM Spindle Chiller, reference the VR/GM - Haas Spindle Chiller chapter of the Haas Spindle Chiller Operator's/Service Manual.

Spindle Air Regulator

Reconfigure the Air Solenoid fitting, Move the restrictor orifice from before 90° fitting to before the Tee Brass fitting. 


Note: No parts required for corrective action.

B/C-Axis Compensation

Follow the steps on the H-5AX - DOUBLE YOKE - HDC - B/C-AXIS COMPENSATION procedure to compensate the B and C-Axis.

H-5AX - DOUBLE YOKE - HDC - B/C-AXIS COMPENSATION

M23 Barrel Connectors

1

Disconnect M23 barrel connectors and verify the pins are not bent.

Carefully adjust the pins if needed.

2

Disconnect M23 barrel connectors and verify the pin holes are not covered by the back plate.

Carefully adjust the back plate if needed.

 Note: The back plate should be visible but should leave a majority of the hole open for the pin.

Spindle Chiller Fluid Leaking

If the machine has been crashed. Check if there is Spindle Chiller fluid [1] leaking between spindle cartridge and spindle mount plate.

Warning: The machine should be stopped and powered off immediately if signs of coolant or chiller fluid is seen leaking from between the spindle and spindle mount plate.

The spindle head needs to be replaced. See H-5AX Double Yoke Spindle Head - Replacement - AD0743 for part number and how to replace the spindle head.

Crashed Spindle Head Correction

Follow the steps listed in the H-5AX Double Yoke - Crashed Spindle Head Correction procedure to correct a spindle head that has been crashed.