Precision Zone Are Experts in Okuma BDU AC Servo Drive Series Repair

At Precision Zone, we specialize in Okuma product repairs which include a wide range of AC Servo drives. One of the many types of servos we service is the Okuma BDU series servo.

Commonly found on Okuma’s LB15 and LC30 turning centers, this single axis servo drive continues to deliver precision and power even today. Ranging from 15 amp output up to 75 amps, this drive delivers reliable and efficient power over a few select output capacities. These BDU-A type amps are most often seen with Okuma 5000 control.

Our team of repair technicians evaluate and test each BDU drive in our custom built simulator.

When assessing the functionality of a Okuma BDU Servo Drives, our highly skilled repair team of engineers and technicians employs a basic four step troubleshooting process:

  • 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 mega ohm 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 BDU Servos

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. 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, printed circuit boards 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

Output Module Testing

Precision Zone repair technicians use digital multimeters with diode testing capabilities and also take resistance measurements to conduct a static test. For these units in particular, our team of technicians uses the diode function of the multimeter as well as huntron devices to check the output modules.

Positive Lead Negative Lead Reading
U Positive Bus Terminal 0.34V-0.40V
V Positive Bus Terminal 0.34V-0.40V
W Positive Bus Terminal 0.34V-0.40V
Negative Bus Terminal U 0.34V-0.40V
Negative Bus Terminal V 0.34V-0.40V
Negative Bus Terminal W 0.34V-0.40V

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

Checks Under Power and Alarm Code Verification

Upon successfully passing all visual and static checks, the drive is tested under power. Any reported alarm codes are verified and if no alarms are present or once the drive has been fully repaired, the drive is tested in our Okuma series simulator. Alarms and drive status can be verified on the LEDs directly on the servo pack.

On the BDU servo packs, there are a handful of red and yellow LEDs to display alarm status. A single green LED (PSON) shows power is supplied to the control board. The yellow LEDs serve as warnings, while the red LEDs display specific alarms. See the following table for detailed descriptions of the alarms.

Alarm Code Color Description Quick Checks
PH Loss Red Phase loss in 220 VAC supplied to drive
  • Check each phase of incoming power. Make sure all 3 are balanced and in range
VR Loss Red The + or - 12 or 5 VDC has dropped below specifications
  • Check all connections and wiring
  • Verify incoming voltages
  • With power off, make sure all boards are seated properly and all screws are tight
IOCM Red Overcurrent in the motor
  • Check all wiring and ensure that all terminal screws are tight
  • Check the motor and motor cables for low winding resistance
IOCS Red Overcurrent in the Servo
  • Ensure that the interboard connectors are securely inserted between the control and power boards
  • Power off, disconnect motor and power up. If LED is still lit, repair of the servo drive is necessary
HV Red DC Voltage is abnormally high
  • Measure the incoming R-S-T voltages with a multimeter. Standard voltage levels reside between 170 and 222 VAC
LV Red Undervoltage
  • Check incoming power with a multimeter
  • Check to make sure voltage input is at least 170 VAC
  • Make sure circuit breaker is ON
OC Yellow Overcurrent
(triggered at 10% of IOCM trigger level)
  • Warning
SAT Yellow Saturation
(drive received heavy load)
  • Warning
SAOP Yellow Sub Amp Operation
(turns off when machine ready signal is received)
  • Warning

In order to make sure that your business keeps going, Precision Zone offers free technical support on any component that you may be having issues with. For more information on troubleshooting the Okuma BDU AC Servo Drives or for any other machine related issues, please contact us via phone at 800-551-4420 or email at for further assistance.

Precision Zone Repair Benefits for Okuma BDU AC Servo Drives

  • Free evaluation by expert technicians include:
  • Visual Inspection
  • Static Check
  • Power Tests
  • Free Job Estimate
  • 12 month warranty on our parts and labor
  • Flat Price
  • Exchange Options
  • Rush Service Options

Contact Us To Start Your Repair Today!

Recently Repaired Products

Okuma BDU-30A image BDU-30A is an
Drives-AC Servo manufactured by Okuma
Discovered issues: Bad Gate Section/Board, Bad Magnetic Contactor, Relay
Drive Type: DC Input ; AC output Servo drive
Motor Current Rating: 30A
Option: A

Okuma BDU-50A image BDU-50A is an
Drives-AC Servo manufactured by Okuma
Discovered issues: Bad Control Section/Board, Bad Gate Section/Board, Bad Magnetic Contactor, Relay, Bad Power Section/Board, Physical Damage to the Drive
Drive Type: DC Input ; AC output Servo drive
Motor Current Rating: 50A
Option: A

Okuma BDU-75A image BDU-75A is an
Drives-AC Servo manufactured by Okuma
Discovered issues: Bad Gate Section/Board, Bad Output Transistors/SCRs
Drive Type: DC Input ; AC output Servo drive
Motor Current Rating: 75A
Option: A

Okuma BDU-15A image BDU-15A is an
Drives-AC Servo manufactured by Okuma
Discovered issues: Bad Gate Section/Board
Drive Type: DC Input ; AC output Servo drive
Motor Current Rating: 15A
Option: A