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Fanuc Repair Specialists for A06B-60889 and A06B-6090 AC Servo Units

Here at Precision Zone, one of our specialties is the repair services of Fanuc Alpha servo units. One series that we often work on is the A06B-6089 and A06B-6090 series.

Typically found on machines running Fanuc’s 18-T control, the A06B-6089 and A06B-6090 Alpha series servos sport a slightly redesigned look from the A06B-6079 and A06B-6080 Alpha servos. Instead of the Honda-style connectors for interconnecting the drives, these A06B-6089 and A06B-6090 units have a standard terminal strip. Instead of jumpers to select communication type, these units have a series of DIP switch settings above the display LED. The seven-segment LED displays the status of the drive and any alarms in the alarmed out state.

When assessing the functionality of a drive, our repair team conducts a four-step evaluation:

    1. Visual Overview
    2. Static Test
    3. Checks Under Power
    4. Alarm Codes Verification

This overview is Precision Zone’s basic troubleshooting process. Once our repair team starts on the job, we use specialized and customized testing fixtures, Huntron trackers, signal generators, oscilloscopes, milli and megaohm meters, as well as any other necessary tools we have available to assure quality repair work. Most importantly, every repair is fully tested in our custom-built simulators under load with a motor to replicate real-life working environment.

Precision Zone goes as far as using heating chambers and overnight dynamic testing, when applicable, to guarantee performance of the repaired product when it arrives back with the customer.

Repair Process for Fanuc Fanuc Alpha Series Servo Amplifiers

Visual Overview

When conducting a visual check, the technician inspects the drive for any mechanical damage to the drive itself and any printed circuit boards (PCB). The technician then proceeds to verify connections are tight and correct inside the drive and there are no loose screws, wires or debris. Additionally, the unit is checked for any burn marks on the components, PCBs or chassis. During the visual inspection, excessive dirt on cooling components is noted as well as the functionality of the heat sink.

Basic Static Check

Input Module Testing

The input modules on these units can be tested by use of a digital multimeter with diode checking capabilities. Upon removing the cover, all of these terminals can be located along the terminal strip found within the unit.

Since the DC bus is not easily accessible due to the design, we check the inputs once the drive has been partially disassembled for access to the bus.

Output Module Testing

Using the same procedure as above, the output modules can be checked as well. Our technicians are also equipped with huntron devices further verify their integrity. We check for any damage to the output transistors and the gating sections.

The capacitor values on the PCBs are verified and any relays, contactors or circuit breakers in the drive are examined to ensure proper functionality.

List of Fanuc Alpha Series Common Alarms

Alarm Code Description Checks
Al 1 Overvoltage Alarm
  • The three-phase input voltage is probably higher than the rating. Check the voltage and correct it as required
  • The connection of the separate regenerative discharge unit is probably incorrect. Check the connection
  • The resistor of the separate regenerative discharge unit is probably defective. Disconnect the wiring of the regenerative discharge unit and check the resistance. If it is not within +20% of the rating (described in Section 3. 5), replace the regenerative discharge unit
Al 2 Low Voltage, Control Power
  • Check three phases input voltage to power supply module
  • The emergency stop input signal is probably short- circuited. Remove the CX4 connector from the amplifier. If the alarm condition disappears, check the connection of the external cable
Al 4 Regenerative discharge control circuit failure alarm
  • The connection of the separate regenerative discharge unit is probably incorrect. Check the connection
  • The resistor of the separate regenerative discharge unit is probably defective. Disconnect the wiring of the regenerative discharge unit and check the resistance. If it is not within +20% of the rating (described in Section 3. 5), replace the regenerative discharge unit
Al 5 Over-regenerative discharge alarm
  • The average regenerative discharge energy is probably too high. Reduce the frequency of acceleration/deceleration
  • The connection of the thermostat line to the separate regenerative discharge unit is probably incorrect. Check the connection
  • The thermostat of the separate regenerative discharge unit is probably defective. Disconnect the wiring of the regenerative discharge unit, and check the thermostat. If the thermostat is open when the regenerative discharge unit is not hot, replace the regenerative discharge unit
  • The transformer has probably overheated. Check the ambient temperature, motor output, and transform rating
Al 7 Dynamic brake circuit failure alarm
  • The connection between the NC and servo amplifier is probably incorrect. Check the connection
Alarm Abnormal Current Alarm Check
8
9
b		 L-Axis
M-Axis
L & M Axes
  • Disconnect motor leads from amp
  • Meg the motor
  • Check resistance phase to phase to motor (U, V, W)
  • Check amp output legs to ground for any shorts
Alarm IPM Alarm Check
8
9
b		 L-Axis
M-Axis
L & M Axes
  • Disconnect motor leads from servo and release the servo from EMG stop
  • If alarm goes away, check the insulation of the motor leads with a megger
  • If possible, swap drives or axes and see if alarm follows drive

This list of checks for certain alarms is primarily a good starting point and if any further troubleshooting or technical support is needed feel free to contact us via phone or email to get in touch with our experienced tech support team.

Precision Zone Repair Benefits for Fanuc AC Servo Alpha Series

    1. FREE evaluation by expert technician includes:
    • Visual Inspection
    • Static Check
    • Power Tests
    2. FREE job estimate
    3. 12 month warranty on our parts and labor
    4. Flat Price
    5. Exchange Option
    6. Rush Service


Recently Repaired Products

Fanuc A06B-6089-H105 image A06B-6089-H105 is an
Drives-AC Servo manufactured by Fanuc
Discovered issues: Bad Capacitor(s), Bad Circuit Board Component(s), Bad Output Transistors/SCRs
Part Group: A06B
Model & Interface Type: Alpha Servo Amplifier Unit
Number of Axes & Description: 1 axis, SVU1-80

Fanuc A06B-6090-H006 image A06B-6090-H006 is an
Drives-AC Servo manufactured by Fanuc
Discovered issues: Bad Capacitor(s), Blown Circuit Board (Through Hole), May Require Board Replacement
Part Group: A06B
Model & Interface Type: Alpha Servo Amplifier Unit series C
Number of Axes & Description: 1 axis, SVUC1-80
Module: none

Fanuc A06B-6089-H210 image A06B-6089-H210 is an
Drives-AC Servo manufactured by Fanuc
Discovered issues: Bad DC Bus Capacitors
Part Group: A06B
Model & Interface Type: Alpha Servo Amplifier Unit
Number of Axes & Description: 2 axis, SVU2-20/80

Fanuc A06B-6089-H104 image A06B-6089-H104 is an
Drives-AC Servo manufactured by Fanuc
Discovered issues: Bad Capacitor(s)
Part Group: A06B
Model & Interface Type: Alpha Servo Amplifier Unit
Number of Axes & Description: 1 axis, SVU1-40

Fanuc A06B-6090-H244 image A06B-6090-H244 is an
Drives-AC Servo manufactured by Fanuc
Discovered issues: Bad Capacitor(s), Bad Output Transistors/SCRs
Part Group: A06B
Model & Interface Type: Alpha Servo Amplifier Unit series C
Number of Axes & Description: 2 axis, SVUC2-40/40
Module: none

Fanuc A06B-6090-H233 image A06B-6090-H233 is an
Drives-AC Servo manufactured by Fanuc
Discovered issues: Bad Magnetic Contactor, Relay, Leaky Capacitors (Open, Corroded Traces)
Part Group: A06B
Model & Interface Type: Alpha Servo Amplifier Unit series C
Number of Axes & Description: 2 axis, SVUC2-12/12
Module: none

Fanuc A06B-6089-H206 image A06B-6089-H206 is an
Drives-AC Servo manufactured by Fanuc
Discovered issues: Bad Gate Section/Board, Bad Magnetic Contactor, Relay, Bad Output Transistors/SCRs, Leaky Capacitors (Open, Corroded Traces)
Part Group: A06B
Model & Interface Type: Alpha Servo Amplifier Unit
Number of Axes & Description: 2 axis, SVU2-40/40

Fanuc A06B-6090-H004 image A06B-6090-H004 is an
Drives-AC Servo manufactured by Fanuc
Discovered issues: Bad Circuit Board Component(s)
Part Group: A06B
Model & Interface Type: Alpha Servo Amplifier Unit series C
Number of Axes & Description: 1 axis, SVUC1-40
Module: none