Our Team Expertly Repairs Mitsubishi Freqrol A024/A044 General-Purpose Inverter Units

Here at Precision Zone, one of our specialties is the repair services of Mitsubishi Inverter units. One series that we often work on is the Freqrol-A024/A044 series.

FR-A024/A044 inverters are offered in sizes ranging from 100W up to 3700W and do have the option to use single-phase input power. If single-phase is being used, only 2/3 of the diodes are used and the capacitor ripple will be increased. Due to this, temperatures of the converter and capacitor will be higher and derate the output current will be required.

There is an optional parameter unit, FR-PU03E, which can be installed directly onto the unit or used remotely using an optional cable. This can be used to monitor faults as well as install parameters.

These units offer a few different operation modes as well. It can be controlled in external operation mode which utilizes external signals as the control method, PU operation mode which uses the parameter unit as the control method, or combined operation mode which allows external signals and the parameter unit to be used as the control method.

When assessing the functionality of a Mitsubishi 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 is a basic overview of the troubleshooting process we use here at Precision Zone. Once our repair team begins evaluating and repairing the unit, our highly skilled team of engineers and technicians use customized testing stands, Huntron trackers, signal generators, oscilloscopes, milli and mega ohmmeters, as well as any other instruments needed to ensure the highest quality of repair and testing that meet our standards. Furthermore, to ensure that the repaired unit can endure working conditions, every repair is fully tested in our custom built testing stands under load with a motor to replicate these real-life working environments.

Precision Zone will even use heat chambers and perform dynamic testing when needed to guarantee performance of the repaired product when it arrives back with the customer.

Repair Process for Mitsubishi FR-A024/A044 General Purpose 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 correct and tight within the drive and that there are no loose screws, wires, or debris. Additionally, burn marks are also checked for 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 Mitsubishi General Purpose Inverter 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.

Positive Lead Negative Lead Reading
R 'P' Terminal 0.37V-0.39V
S 'P' Terminal 0.37V-0.39V
T 'P' Terminal 0.37V-0.39V
'N' Terminal R 0.37V-0.39V
'N' Terminal S 0.37V-039V
'N' Terminal T 0.37V-0.39V

Output Module Testing

Using huntron devices to further verify the integrity, our technicians execute the same type of testing for the output modules.

Positive Lead Negative Lead Reading
U 'P' Terminal 0.40V-0.42V
V 'P' Terminal 0.40V-0.42V
W 'P' Terminal 0.40V-0.42V
'N' Terminal U 0.40V-0.42V
'N' Terminal V 0.40V-0.42V
'N' Terminal W 0.40V-0.42V

Common Alarms for the Mitsubishi FR-A024/FR-A044

Alarm Code Description Checks
Overcurrent detected during acceleration (OC1), constant speed (OC2), or deceleration (OC3)
  • Check cables for poor insulation
  • Perform magaohm test on motor
  • Use 'Output Module Testing' test to verify modules
  • Check for ground faults
ERR Operation setting error, reset signal ‘ON’, parameter unit not connected properly, high input voltage, faulty internal circuitry
  • Verify operation M=method
  • Verify proper wiring
  • Check input voltage
  • Swap drive out with another if applicable
FAN The cooling fan within the inverter has stopped functioning
  • Check for any debris lodged within fan fins
  • Verify wiring
  • Replace fan
GF Ground fault has occured on the output of unit
  • Check motor or wire for ground fault
  • Check input/output terminals to ground for leakage
  • Replace Drive

For a full list of Mistubishi FR-A024/A044 alarms from the manual:


The list of alarms within the manual is a good starting point for troubleshooting the Mitsubishi General Purpose Inverters. If any additional troubleshooting assistance is needed for the FR-A024 or FR-A044, Precision Zone offers free technical support. Feel free to contact us via phone or email to get in touch with our experienced technical support team.

Learn the benefit of repairing your Mitsubishi FR-A024/FR-A044 General Purpose Inverters 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

Mitsubishi FR-A024-0.75KP image FR-A024-0.75KP is an
Inverter-General Purpose manufactured by Mitsubishi
Discovered issues: Bad Control Section/Board, Bad Gate Section/Board, Bad Power Section/Board, Bad Input Diodes/SCRs, Bad Output Transistors/SCRs
Series: FR-A024; 200V
Capacity: 0.75kW
Parameter Unit: Installed
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Mitsubishi FR-A024-1.5K image FR-A024-1.5K is an
Inverter-General Purpose manufactured by Mitsubishi
Discovered issues: Leaky Capacitors (Open, Corroded Traces), Bad Cooling Fans
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Mitsubishi FR-A024-1.5K-UL image FR-A024-1.5K-UL is an
Inverter-General Purpose manufactured by Mitsubishi
Discovered issues: Bad Capacitor(s), Bad Circuit Board Component(s), Bad Control Section/Board, Bad Cooling Fans, Bad Gate Section/Board, Bad Output Transistors/SCRs, Bad Power Section/Board, Leaky Capacitors (Open, Corroded Traces)
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Mitsubishi FR-A024-1.5KP image FR-A024-1.5KP is an
Inverter-General Purpose manufactured by Mitsubishi
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Capacity: 1.5kW
Parameter Unit: Installed
Version: Japanese