Our Team Are Experts On Mitsubishi HA-FF AC Servo Motor Repairs

Here at Precision Zone, owe specialize in Mitsubishi product repairs servicing a wide range of AC servo motors. One series that we work on quite often is the Mitsubishi HA-FF series AC servo motor.

The HA-FF series AC servo motors from Mitsubishi come in quite a few different variations. The rated output ranges from 50W and goes up to 600W. The rated speed on this series is 3000 rpm’s and input power can be supplied through flying leads or as a cannon connector. This series also has the option to include an electromagnetic brake, though not all models will have this installed. There is a reduction gear option allowing these to be offered without the gear, with a gear for industrial machines, or with a gear for precision applications. Shaft types can be either standard, with or without keys, or a D-cut shaft for use with an electromagnetic brake.

When assessing the functionality of a motor, our engineering team typically conducts a six step check:

    1. Visual Overview
    2. Static Test
    3. Back EMF
    4. Feedback Check
    5. Alarm Code Troubeshooting
    6. Disassembly and Cleaning

This overview is Precision Zone’s basic troubleshooting process. Once our repair team starts on the job we use specialized, customized test fixtures, SKF Baker AVAIV-4, Huntron devices, signal generators, oscilloscopes, milli and mega ohm meters, and other necessary tools to assure quality repair.

Most importantly, every repair is fully tested in custom-built simulators under load to replicate real-life working conditions.

Repair Process for Mitsubishi HA-FF Series AC Servo Motors

Visual Overview

When conducting a visual check, the technician inspects the motor for any mechanical damage to the power connecter, junction box, rotor shaft, oil seals and encoder covers. During the visual inspection the technician notes excessive dirt, oil or grease on cooling fans and all other parts of the motor.

Static Check Basic

Precision Zone repair technicians use an SKF Baker Advanced Winding Analyzer to fully evaluate the stator winding. The SKF Baker performs a wide range of electrical tests, including surge, DC hi-pot, mega-ohm, and winding resistance tests. In the instance of winding resistance each phase is tested with each other; and the mega ohm readings should be no less than 200 mega ohms.

Winding Resistance Testing

Positive Lead Negative Lead Approximate Reading
U V 0.2Ω - 10Ω¹
V W 0.2Ω - 10Ω¹
W U 0.2Ω - 10Ω¹
¹ Reading should be balanced across all three phases.

Mega Ohm Testing

Positive Lead Negative Lead Approximate Reading
U Ground/Unpainted stator area Well above 200 MΩ ²
V Ground/Unpainted stator area Well above 200 MΩ ²
W Ground/Unpainted stator area Well above 200 MΩ ²

² Our recommended minimum is 200 MΩ. Anything close to that 200 MΩ reading can still cause issues as the motor heats up and that value begins to drop lower.

Back EMF Check

If a servo motor passes the static checks it will be back driven and have the back EMF checked. With our in house magnetizing service we can bring back to life servo motors with weak magnets.

Feedback Check

Repair technicians can test encoders in a number of different ways. Our Mitchell Electrics TI-5000EX system can be used to read, write and record encoder count and data information. We have Mitchell Electrics TI-5250 systems that can be used to see live encoder pulses on an oscilloscope. Connecting encoders directly to the manufacture’s drive is another way we can verify if an encoder is working correctly.

Disassembly and Cleaning

All motors are fully dissembled, washed, and baked. Rotors are checked for bent shafts and bearing journal common problems. The stator winding is rechecked after the baking process. Holding brakes are refurbished and the holding torque is checked. Both the drive end and opposite drive end housing bearing surfaces are checked. Once the evaluation is completed a computer report is generated with all the findings.

Common Failures and Troubleshooting with Mitsubishi AC Servo Motors

Failure Type Common Cause Troubleshooting
Overcurrent Poor motor or cable insulation, phase to phase, short, phase to ground short
  • Perform mega ohm test, first through cables, then at motor terminals (if applicable)
  • Monitor incoming for any instantaneous power failures
Encoder related alarms Encoder failure, issue with feedback cabling, control board failure on drive side
  • Check encoder waveforms if oscilloscope and back-driving of motor is available
  • Connect motor with a different drive if applicable, contact Precision Zone support for further information
Motor shaft is locked up Demagnetization occurred, brake malfunction (where applicable), drive side fault
  • Disconnect motor from drive and attempt to spin by hand, if no brake is used
  • If brake is used, verify that it is disengaging appropriately
  • Contact Precision Zone support for further troubleshooting

The list of checks for certain alarms is primarily a good starting point to troubleshooting this Mitsubishi Servo Motor Series.

Precision Zone offers free technical support on any component that you may be having issues with. We understand that when your machine goes down, your business stops. That is why our number one goal is to provide you with the best service possible so that you can get back up and running immediately. For any further product information or troubleshooting assistance is needed, please contact us via phone at 800-551-4420 or email us.

Precision Zone Repair Benefits for Mitsubishi HA-FF AC Servo Motors

  • Free quotes and evaluations by our expert technicians include:
  • 12-Month Warranty on Our Parts and Labor
  • Decades of Industry Experience
  • Exchange Options
  • Rush Service Options

Contact Us To Start Your Repair Today!


Recently Repaired Products

Mitsubishi HA-FF43 image HA-FF43 is an
Motors-AC Servo manufactured by Mitsubishi
Discovered issues: Bad DE Bearing, Bad ODE Bearing, Bad Condition - Requires Reconditioning, Bad Power Connector
Servomotor Type: HA-FF series, low inertia, small capacity
Rated Output: 400W
Rated Speed: 3000 RPM
Input power supply form: Lead
Electromagnetic brake: None
Reduction gear: None
Shaft end: Standard
Version: Japan

Mitsubishi HA-FF33 image HA-FF33 is an
Motors-AC Servo manufactured by Mitsubishi
Discovered issues: Bad DE Bearing, Bad ODE Bearing, Bad Condition - Requires Reconditioning, Bad Power Connector
Servomotor Type: HA-FF series, low inertia, small capacity
Rated Output: 300W
Rated Speed: 3000 RPM
Input power supply form: Lead
Electromagnetic brake: None
Reduction gear: None
Shaft end: Standard
Version: Japan

Mitsubishi HA-FF13 image HA-FF13 is an
Motors-AC Servo manufactured by Mitsubishi
Discovered issues: Bad DE Bearing, Bad ODE Bearing, Bad Condition - Requires Reconditioning
Servomotor Type: HA-FF series, low inertia, small capacity
Rated Output: 100W
Rated Speed: 3000 RPM
Input power supply form: Lead
Electromagnetic brake: None
Reduction gear: None
Shaft end: Standard
Version: Japan

Mitsubishi HA-FF63 image HA-FF63 is an
Motors-AC Servo manufactured by Mitsubishi
Discovered issues: Bad Coil Insulation
Servomotor Type: HA-FF series, low inertia, small capacity
Rated Output: 600W
Rated Speed: 3000 RPM
Input power supply form: Lead
Electromagnetic brake: None
Reduction gear: None
Shaft end: Standard
Version: Japan