Fanuc A06B-6055 AC Digital Spindle Repair Specialists

Here at Precision Zone, one of our specialties is the repair services of Fanuc Digital AC Spindle units. One series that we often work on is the A06B-6055 series.

The A06B-6055 is one of Fanuc’s larger AC digital spindle drive units. The standard version of this unit comes in either a 4500 or 6000 max RPM offering. There is also a high-speed variant that doubles the max speed up to 12000 RPM. Five seven-segment displays allow for display readout, alarm monitoring, and parameter setting. Parameters allow the user to makes changes to everything from setting the motor rated voltage to zero speed detection level to orientation and rigid tapping settings. The parameter settings allow for easy adjustments whenever PCBs may be switched out and adjustment data is lost.

When assessing the functionality of a spindle 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 AC Digital Spindle Drives

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, these terminals can be located along the terminal strip found within the unit. The ‘P’ and ‘N’ terminals are the positive and negative sides of the main bus capacitor respectively.

Positive Lead Negative Lead Reading
R 'P' Terminal 0.40V-0.45V
S 'P' Terminal 0.40V-0.45V
T 'P' Terminal 0.40V-0.45V
'N' Terminal R 0.40V-0.45V
'N' Terminal S 0.40V-0.45V
'N' Terminal T 0.40V-0.45V

Output Module Testing

Using the same type of test as above, the output modules can be checked as well. Our technicians are also equipped with huntron devices further verify their integrity.

Positive Lead Negative Lead Reading
U 'P' Terminal 0.71V-0.74V
V 'P' Terminal 0.71V-0.74V
W 'P' Terminal 0.71V-0.74V
'N' Terminal U 0.71V-0.74V
'N' Terminal V 0.71V-0.74V
'N' Terminal W 0.71V-0.74V

List of Common Alarms for Fanuc A06B-6055 AC Digital Spindle Units

Number Alarm Display Checks
AL-01 Motor Overheat
  • Check the motor fan to ensure that it spins
  • Clear any dirt or debris from the motor fan
  • If this happens while running, check to ensure that the drive/motor are not overloaded at the point of failure
  • Check the connections between the drive and motor for loose connections
AL-03 Fuse on DC Link Broken
  • This indicates a blown fuse in the DC link section. Check fuse F4
  • Check the transistor module
AL-04 Input Fuse/Power Fault
  • This alarm indicates an open fuse or an open phase on the input power
  • Check the incoming power and ensure that all three phases are proper and balanced
  • Check fuses F1-F3
  • Check transistor unit
  • Check connectors of power cables and ensure all connections to PCBs are good
AL-08 High Input Voltage
  • Check incoming power to the drive and correct if needed
AL-09 Overheat
  • Check cooling fans
  • Check load with load meter
  • Make sure drive is properly ventilated/cooled and any dirt, debris or obstructions are cleared (may need to use compressed air)
AL-12 Overcurrent DC Link
  • Check output transistors for any short circuits or visible damage
  • Disconnect motor from spindle and turn on machine. If alarm persists, the drive likely needs repair
  • If transistor modules are good and motor winding resistance is ok, check motor cable
AL-13 CPU Memory Data Alarm
  • Replace spindle control PCB
  • If issues persist, repair to the drive is needed

This list of checks for certain alarms is primarily a good starting point; however, it is not a comprehensive list of alarm troubleshooting. 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 Spindle 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 Options


Recently Repaired Products

Fanuc A06B-6055-H212 image A06B-6055-H212 is an
Drives-AC Spindle manufactured by Fanuc
Discovered issues: Bad Capacitor(s), Bad Circuit Board Component(s), Bad Cooling Fans, Bad Output Transistors/SCRs
Part Group: Motors and Drives
Series: AC Spindle servo unit
Part Type: Drive
Unit: 2
Model: Model 12
Factory Designated: none

Fanuc A06B-6055-H208 image A06B-6055-H208 is an
Drives-AC Spindle manufactured by Fanuc
Discovered issues: Bad Capacitor(s), Bad Circuit Board Component(s), Bad Cooling Fans, Bad Output Transistors/SCRs
Part Group: Motors and Drives
Series: AC Spindle servo unit
Part Type: Drive
Unit: 2
Model: Model 8
Factory Designated: none

Fanuc A06B-6055-H115 image A06B-6055-H115 is an
Drives-AC Spindle manufactured by Fanuc
Discovered issues: Bad Fuse, Bad Output Transistors/SCRs
Part Group: Motors and Drives
Series: AC Spindle servo unit
Part Type: Drive
Unit: 1
Model: Model 15
Factory Designated: none

Fanuc A06B-6055-H422 image A06B-6055-H422 is an
Drives-AC Spindle manufactured by Fanuc
Discovered issues: Bad Capacitor(s), Bad Circuit Board Component(s), Bad Fuse, Bad Output Transistors/SCRs
Part Group: Motors and Drives
Series: AC Spindle servo unit
Part Type: Drive
Unit: 4
Model: Model 22
Factory Designated: none

Fanuc A06B-6055-H222 image A06B-6055-H222 is an
Drives-AC Spindle manufactured by Fanuc
Discovered issues: Bad Capacitor(s), Bad Circuit Board Component(s), Bad Cooling Fans
Part Group: Motors and Drives
Series: AC Spindle servo unit
Part Type: Drive
Unit: 2
Model: Model 22
Factory Designated: none

Fanuc A06B-6055-H106 image A06B-6055-H106 is an
Drives-AC Spindle manufactured by Fanuc
Discovered issues: Bad Capacitor(s), Bad Circuit Board Component(s), Bad Cooling Fans
Part Group: Motors and Drives
Series: AC Spindle servo unit
Part Type: Drive
Unit: 1
Model: Model 6
Factory Designated: none

Fanuc A06B-6055-H112 image A06B-6055-H112 is an
Drives-AC Spindle manufactured by Fanuc
Discovered issues: Bad Capacitor(s), Bad Circuit Board Component(s), Bad Fuse, No Display
Part Group: Motors and Drives
Series: AC Spindle servo unit
Part Type: Drive
Unit: 1
Model: Model 12
Factory Designated: none

Fanuc A06B-6055-H108 image A06B-6055-H108 is an
Drives-AC Spindle manufactured by Fanuc
Discovered issues: Parameter/Setting Adjustment
Part Group: Motors and Drives
Series: AC Spindle servo unit
Part Type: Drive
Unit: 1
Model: Model 8
Factory Designated: none

Fanuc A06B-6055-H203 image A06B-6055-H203 is an
Drives-AC Spindle manufactured by Fanuc
Discovered issues: Bad Circuit Board Component(s)
Part Group: Motors and Drives
Series: AC Spindle servo unit
Part Type: Drive
Unit: 2
Model: Model 3
Factory Designated: none