Our Team Expertly Repairs Okuma VAC-5 Spindle Units

Here at Precision Zone, one of our specialties is the repair services of Okuma spindle drive units. One series that we often work on is the VAC-5 series.

VAC-5 spindle units are offered in sizes ranging from 6kW to 30kW and can act as a direct replacement for some of the earlier versions of this series. A full list of the compatibility between the VAC-5 and the previous series can be found here. These drive units are ran with the standard optical interface option but can also be offered with an optional analog interface card.

Depending on the system that the VAC-5 unit is being installed in, there can be different configurations to allow proper functionality and get the most out of this spindle drive. These connections will vary, based on the original system, and can replace VAC-1, VAC-2, VAC-3, and even some externally sold systems. Two seven-segment LED displays allow for normal and error status modes to be easily accessible. With these displays in place, quick access to alarm code readings speeds up the troubleshooting process and allows for minimal downtime when issues do arise.

When assessing the functionality of a drive like this Okuma VAC-5 spindle drive, our repair team conducts a four-step evaluation:

    1. Visual Overview
    2. Static Test
    3. Checks Under Power
    4. Alarm Code 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 Okuma VAC-5 Spindle Drives

Visual Overview Check

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

Input module checking on these units is not recommended on-site due to the configuration of the circuit. Between the input terminals and input modules there are capacitors which can create flawed readings while checking input module from the input terminals, so in order to accurately assess the integrity of these components a full disassembly of the drive is required

Ouput Module Testing

The output modules are a bit more cooperative when it comes to static checking. These modules are able to be checked with a standard multimeter with diode checking capabilities. Meter lead and example values can be viewed below and these readings will vary slightly with drive capacity, but each reading should be within 10% of one another. Our technicians are also equipped with huntron devices further verify their integrity.

Positive Lead Negative Lead Reading
R '+' Bus Cap Screw 0.32V-0.62V
S '+' Bus Cap Screw 0.32V-0.62V
T '+' Bus Cap Screw 0.32V-0.62V
'-' Bus Cap Screw R 0.32V-0.62V
'-' Bus Cap Screw S 0.32V-0.62V
'-' Bus Cap Screw T 0.32V-0.62V

Okuma VAC-5 Common Alarms and Warnings

Alarm Code Description Checks


Excessive current has been detected flowing through the output section of the spindle unit
  • Check cables for poor insulation
  • Perform megaohm test on motor
  • Use "Output Module Testing" test to verify modules
  • Check for ground faults
Excessive Speed Deviation
Actual motor speed does not coincide with the speed the spindle unit is expecting to see
  • Verify cutting load is not excessive
  • Verify proper wiring (insulation and ground faults)
  • Veify resolver integrity
  • Swap drive or motor out with a known working unit, if applicable
Communication Error
Control signals through optical fiber cable are unable to communicate properly
  • Verify connector is properly inserted to connection plug
  • Check integrity of the optical fiber cable
  • Check NC unit board and control PCB on spindle

You can find the full list of alarm troubleshooting in the manual, here

For more information on these alarms as well as any other failures, please give us a call at 800-551-4420 or email us today!

Precision Zone Repair Benefits for Okuma Spindle Drives

    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

Okuma VAC5-D22-AIF image VAC5-D22-AIF is an
Drives-AC Spindle manufactured by Okuma
Discovered issues: Bad Gate Section/Board, Bad Output Transistors/SCRs, Excessive Dirt/Debris
Drive Type: VAC5 AC Spindle Drive
Rated Capacity: 22kW
Interface: Analog interface unit type