Precision Zone Expertly Repairs Inverter-General Purpose Yaskawa CIMR-MC5 VS-626MC5

Here at Precision Zone, one of our specialties is the repair services of Yaskawa variable frequency inverter units. One series that we often work on is the CIMR-MC5 series.

Yaskawa's MC5 inverter is a variable frequency inverter designed with specific intention to be used as a spindle drive in machine tool applications. This drive has winding change capability during operation and auto-tuning ability. The drive has full-current vector control and an easy to read user interface operator. This digital operator gives the user the ability to vary many performance parameters along with the control type (for example: open loop vs vector control).

In 200V and 400V offerings, these drives come in output ratings from 0.4kW up to 75kW, thus making the MC5 series a versatile spindle line.

When assessing the functionality of a Yaskawa General-Purpose Inverter, our expert repair team of engineers and technicians conducts a four-step check:

    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 Crane Inverter 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, all of these terminals can be located along the terminal strip found within the unit. We look for balanced readings across the three phases.

Positive Lead Negative Lead Reading
L1 '+' Terminal Approximately 0.30V-0.45V
L2 '+' Terminal Approximately 0.30V-0.45V
L3 '+' Terminal Approximately 0.30V-0.45V
'-' Terminal L1 Approximately 0.30V-0.45V
'-' Terminal L2 Approximately 0.30V-0.45V
'-' Terminal L3 Approximately 0.30V-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 '+' Terminal Approximately 0.30V-0.52V
V '+' Terminal Approximately 0.30V-0.52V
W '+' Terminal Approximately 0.30V-0.52V
'-' Terminal U Approximately 0.30V-0.52V
'-' Terminal V Approximately 0.30V-0.52V
'-' Terminal W Approximately 0.30V-0.52V

Common Alarms for the Yaskawa CIMR-MC5 Variable Frequency Inverter Unit

Alarm Code Description Checks
OC Overcurrent
  • Check cables for poor insulation
  • Perform magaohm test on motor
  • If occurring during operation and able to be reset, try to reduce load on motor
GF Ground Fault
  • Check Wiring
  • Check for any direct shorts to ground on the motor or drive output
  • Check for cable damage
OV Over Voltage
  • Check incoming power to the drive (make sure this is balanced across phases and within the appropriate range)
  • Decrease power supply voltage
  • Decrease deceleration time if this alarm occurs during deceleration
PGO PG Disconnection Detected
  • Check for any mis-wiring or cable breaks in PG wiring.
  • Ensure the PG is properly powered
  • Check for open circuits when using the brake
LF Open Phase on Output
  • Make sure terminal connections are not loose
  • Check motor winding for broken wire
  • Check L8-07 and make sure parameters are set correctly


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.

Learn the benefit of repairing your Yaskawa inverter units with Precision Zone

  • Quick and Flexible Service
  • Fully Refurbished, not just repaired
  • Decades of Industry Experience
  • Superior Technology Knowledge and Support

Contact Us To Start Your Repair Today!


Recently Repaired Products

Yaskawa CIMR-MC5U2015 image CIMR-MC5U2015 is an
Inverter-General Purpose manufactured by Yaskawa
Discovered issues: Bad Capacitor(s), Bad Circuit Board Component(s), Bad Cooling Fans, Bad Gate Section/Board, Leaky Capacitors (Open, Corroded Traces)
Drive Type: AC Spindle
Series: MC5
Country Code: USA
Input Voltage: 230V
Output Power: 15kW

Yaskawa CIMR-MC5U2011 image CIMR-MC5U2011 is an
Inverter-General Purpose manufactured by Yaskawa
Discovered issues: Bad Capacitor(s), Bad Control Section/Board, Bad Cooling Fans, Bad Gate Section/Board, Bad Output Transistors/SCRs, Bad Power Section/Board, Excessive Dirt/Debris, Leaky Capacitors (Open, Corroded Traces)
Drive Type: AC Spindle
Series: MC5
Country Code: USA
Input Voltage: 230V
Output Power: 11kW

Yaskawa CIMR-MC5U4011 image CIMR-MC5U4011 is an
Inverter-General Purpose manufactured by Yaskawa
Discovered issues: Parameter/Setting Adjustment
Drive Type: AC Spindle
Series: MC5
Country Code: USA
Input Voltage: 460V
Output Power: 11kW

Yaskawa CIMR-MC5U27P5 image CIMR-MC5U27P5 is an
Inverter-General Purpose manufactured by Yaskawa
Discovered issues: Bad Control Section/Board
Drive Type: AC Spindle
Series: MC5
Country Code: USA
Input Voltage: 230V
Output Power: 7.5kW

Yaskawa CIMR-MC5U47P5 image CIMR-MC5U47P5 is an
Inverter-General Purpose manufactured by Yaskawa
Discovered issues: Bad Gate Section/Board, Leaky Capacitors (Open, Corroded Traces)
Drive Type: AC Spindle
Series: MC5
Country Code: USA
Input Voltage: 460V
Output Power: 7.5kW