Category Archives: Fanuc


A06B-6079-H106 Servo Amplifier by FANUC – Product Spotlight

The A06B-6079-H106 is a 1-axis Alpha Servo Amplifier Module that uses a Type A or Type B interface. When installing the module, observe the ambient temperature and output rating requirements. The continuous output rating  or continuous operation period of some amplifiers may fall as ambient temperature increases. If the amplifier is used continuously with an excessive load applied, the amplifier may be damaged. Before operating the amplifier for the first time, mount and adjust the speed and position detectors so that an appropriate waveform is obtained. If this is not done, the motor may not rotate normally or the spindle may fail to stop as desired.

If the motor makes any abnormal noise or vibration during operation, stop operation immediately. If operation is continued, the A06B-6079-H106 could become damaged. Take corrective action before continuing with operation. Be sure to only replace the battery when the servo amplifier is on. If the battery is replaced while the power is turned off, the stored positioning data will be lost. Also ensure that the battery connector is correctly inserted. The cover on the front of the A06B-6079-H106 carries a label indicating the specification code. When mounting a previously removed front cover, take care to mount the correct cover to the right unit.

You can observe an instantaneous motor current value on the A06B-6079-H106 by checking the voltage across a reference voltage check pin and a motor current check pin with an oscilloscope. You cannot use a device such as a multimeter to find the correct values. To check the power supply voltage, use the reference voltage check pin and the power check pin with a multimeter, oscilloscope, or similar. This will tell you the power supply voltage for the control circuit in the amplifier.

MRO Electric and Supply has new and refurbished A06B-6079-H106 Servo Amplifiers available now. For more information or to request a quote call us at 800-691-8511 or email us at


FANUC A06B-6079-H206 – Beyond the User Manual

The FANUC A06B-6079-H206 is a 2-axis servo amplifier module. Its standard dimensions are 380 x 60 x 307 mm. The Status display is a 7-segment LED that indicates the operation status on the module. If the Status display is not on then the power is not turned on, the cable has a power connection, or the module is defective. If the module is defective, replace the fuse or servo amplifier. If there is a single middle line on the display, the control power supply is waiting for the ready signal. If all the outside lines are on, the servo amplifier is ready to operate and the servo motor is supplied with power. If an alarm is issued on the servo amplifier, a value other than “0” and “-” is displayed.

A pin board can be used with the A06B-6079-H206. The use of a check pin board allows you to observe the signals inside the servo amplifier. CN1 and CN2 are wired with a one to one correspondence. The connector pin numbers correspond to the check pin numbers. You can observe an instantaneous motor current value by observing the voltage across a reference voltage check pin and a motor current check pin with an oscilloscope. Note that you cannot use a device as a multimeter to observe the correct values. You can also measure the voltage across a reference voltage (0V) check pin and a power check pin with a multimeter, oscilloscope, or the like to observe the power supply voltage fr the control circuit inside the servo amplifier. If the measured voltage is within 5% relative to the nominal voltage, the measured voltage is considered acceptable.

A special lithium battery can be installed in the A06B-6079-H206. Be sure to install the battery with correct polarity, otherwise it may overheat, blow out, or catch fire. Use the factory-installed protection sockets in the unused connector after installing. This can help prevent the battery from short-circuiting.

MRO Electric and Supply Company sells new and refurbished A06B-6079-H206 servo amplifier modules.  To request a quote or for more information, please email or call 800-691-8511. 



Troubleshooting a Fanuc Motor

Here are some basic principles for troubleshooting a FANUC motor circuits with meter or megohm meter. This procedure will show you how to test for shorts in windings, cables, or opens. Before starting to test, make sure to turn all all the power sources to the machine and then disconnect the 3-phase motor lines from the drive end. Visually confirm that there are no problems with the cable and then begin testing.

Testing for a short to ground:

  • Using an Ohm meter: Disconnect all power from machine. Check all three wires at T1, T2, and T3 (all three phases) to the ground wire. The readings for this should be infinite, and if it is zero or reads any continuity then there is a problem with the motor or the cable. For this disconnect the cable and check each separately. Be sure to make sure leads on both ends are not touching anything, including the other leads. Most servo motor shorts can be ready with a regular quality  meter going to at least 10 megaohms.
  • Using a Megohm meter: Disconnect all power from machine. Check all three wires at T1, T2, and T3 (all three phases) to the ground wire. Reading should be between 600-2000 Megohms. Most shorts will be below 20 Megohms. Be careful not to touch the leads or the wires to anything when taking the reading because it can give a false reading. There should be about 1000 Ohms of resistance for each volt of incoming power, but this is not a standard rule. If it is 230meg to 600meg there may be deterioration in the cable.

Testing for Open or Short in the windings:

  • Using an Ohm meter: Disconnect all power from the machine. Put meter on ohms and test T1 to T2, T2 to T3, and T1 to T3. The range should be between 0.3 and 2.0 ohms, with most being at about 0.8 ohms. If it is zero there is a short between the two phases. If it is an open the reading will be infinite or well above 2,000 ohms.
  • Cable and plug notes: Often times the connector on the cable to the motor will get coolant in it. You can dry it out an retest, if it is still bad the inserts will get burn marks in them and cause a slight short, so they need to be replaced. If it is a DC motor, check the brushes. There should be 3-4 round caps to remove around the motor. Under these there is a spring with a square block (brush). Check to see how much is left, they may need to be replaced.


MRO Electric has a large stock of FANUC motors available. If you would like a replacement or spare, or if you have any questions, please call 800-691-8511 or email
FANUC Motors
FANUC Motors

Human Machine Interface (HMI) Retrofitting

At MRO Electric and Supply, we are experts at retrofitting older HMIs with a new interface that is clean, modernized, and still works with your system.

Take this older Fanuc HMI as an example. The old CRT display has begun to fade out, making its use inefficient and none user-friendly. Old CRT screens are also prone to overheating, and they take up a lot of much needed space.

Fanuc HMI
Fanuc HMI Pre-Retrofit

A new LCD retrofitted screen can give you more accessibility, brighter displays, and user-friendly colors. MRO Electric can quickly update your HMI at a fraction of the cost of replacing your whole HMI. You also don’t have to rewrite your programming, or waste time and resources replacing your whole system.

Fanuc HMI next to LCD Retrofit
Fanuc HMI next to its LCD Retrofit

Below is a fully retrofitted Fanuc HMI with an LCD monitor. This lighter, energy-efficient replacement adds years of life and service to existing legacy equipment, and eliminates potential future downtime. In addition, all of our HMI repairs come standard with a 12 month warranty.

Newly Retrofitted Fanuc HMI
Newly Retrofitted Fanuc HMI

Get in touch with us today to learn more about this cost effective solution for your HMIs. You can request a quote by calling 1-800-691-8511 or by emailing

A06B-6058-H005: Beyond the User Manual

A06B-6058-H005: Beyond the User Manual

Generally, Fanuc AC servo motors, like the A06B-6058-H005, have no parts that wear off or that must be replaced periodically, unlike DC servo motors, which have brushes that must be replaced. However, you should perform period maintenance for servo motors so as to keep their initial performance as long as possible and to prevent breakdowns. AC servo motors have precision sensors — their incorrect use or damage caused during transportation or assembling can result in breakdowns or accidents.

It is recommended that you inspect servo motors periodically, and of course we offer a 12 month warranty on all Fanuc products purchased from MRO Electric.

Receiving and Keeping the A06B-6058-H005

When you receive a A06B-6058-H005 module from MRO Electric, make sure that the motor is exactly the one you ordered, in terms of model, shaft, and sensor specifications, and make sure that no damage has been caused on the motor. Servo motors should be kept indoors as a rule. The storage temperature range is -20 to +60 Celsius. Do not place or install AC servo motors in a place where it is extremely humid and dew is prone to form, where there are steep changes in temperature, where there is constant vibration, or there is lots of dust and trash. Constant vibration may cause damage to the shaft bearings.

Daily Inspection Procedures

Before starting operation, or periodically (once a week or month), you should inspect the AC servo motors for vibration and noise, outside damage, stains and smudges, overheating.

Check the motor for abnormal vibration by hand, and noise by ear when the motor is not rotating, rotating at low speed, and accelerating and decelerating.

Check the Pulsecoding cover (read plastic) for crevices and the motor surface (black coating) for scratches and cracks. If you find a crevice on the Pulsecoder cover, you should replace it. If there is a scratch or a crack on the motor surface, the user should repair it by himself as required. If coating has come off, dry the portion of interest or the entire surface and coat it with paint for machines such as urethane paint.

Check the motor surface and bolt holes for oil or cutting fluid. Wipe off oil and cutting fluid on the surface periodically. Oil or cutting fluid can damage the coating by chemical reaction, possibly leading to failure. Also check how such liquid leaks onto the motor, and repair if needed.

Check to see if the motor is too hot during normal operation. Attach a thermolabel on the motor surface and check it visually to see if the motor becomes too hot during normal operation.

Visit our A06B-6058-H005 product page for more information, or to request a quote email or call 1-800-691-8511



Fanuc A06B-6089-H105 Servo Amplifier – Product Info

The Fanuc Servo Amplifier A06B-6089-H105 is an SVU α series control motor amplifier unit. It can be used within systems with one or two feed axes. This amplifier has an integrated power supply to accommodate smaller systems. The A06B-6089-H105 servo amplifier is in compliance with VDE 0160, UL, and CSA safety standards. For more information please visit our product page here.

Continue reading Fanuc A06B-6089-H105 Servo Amplifier – Product Info

Fanuc Alpha Power Supply Fault Codes

These codes and troubleshooting apply to Fanuc power supplies that begin with part number A06B-6077, A06B-6081, and A06B-6087. On the LED display for these units a “-” will mean that the power supply is not ready while a “0” means that the power supply is powered up correctly. If it reads something other than these two then the power supply has an alarm that needs to be corrected. Below is the list of Fanuc Alpha Power Supply fault codes.

AL-01 : Overcurrent in the Main Power Module.
AL-02 : Cooling Fan Stopped.
AL-03 : The temperature of the main circuit heat sink has risen abnormally.
AL-04 : The DC Voltage has dropped.
AL-05 : The main Capacitor was not recharged within the specified time.
AL-06 : The Input Power Supply is Abnormal.
AL-07 :  In the main circuit the DC Voltage is abnormally high

A common alarm on installation of a new alpha power supply is a AL-05.
If you have this alarm we recommend double checking the bus bar connector at the top of the power supply to make sure it is fully connected.