Mitsubishi Electric MELSERVO-J5 (MR-J5) troubleshooting
MELSERVO-J5 (MR-J5) is the successor to MR-J4, with -G (CC-Link IE TSN), -B and -A variants and MR-J5W multi-axis and MR-J5D drive units. Alarm and warning numbers are three digits followed by a one-digit detail number (for example AL.016.1); MR-J4 used two digits, so MR-J4 AL.16 corresponds to MR-J5 AL.016.
Diagnose this with AI
Try Free Servo Diagnostic Upload a photo of the alarm screen, the fault history or a data export. InduQT compares the evidence and suggests the next useful checks.
How it reports faults
- The amplifier shows the alarm or warning number as three digits plus a detail digit. Mitsubishi notes this changed from MR-J4’s two digits plus detail.
- When an alarm occurs, ALM (Malfunction) turns off. Most alarms are recorded in the alarm history; AL.010.1, AL.037, AL.11D, AL.537 and AL.53A are not. Warnings are not recorded, except AL.0F0 (Tough drive warning).
- For AL.030, AL.045, AL.046, AL.050 and AL.051, remove the cause and allow about 30 minutes of cooling before resetting; do not reset repeatedly.
- After AL.025 (Absolute position erased), perform homing again before operating.
Fault codes
| Code | Name |
|---|---|
| AL.016 | Encoder initial communication error 1 |
| AL.052 | Excessive error |
| AL.010 | Undervoltage |
| AL.017 | Board error |
| AL.01A | Servo motor combination error |
| AL.01E | Encoder initial communication error 2 |
| AL.020 | Encoder normal communication error 1 |
| AL.021 | Encoder normal communication error 2 |
| AL.024 | Main circuit error |
| AL.025 | Absolute position erased |
| AL.030 | Regenerative error |
| AL.031 | Overspeed |
| AL.032 | Overcurrent |
| AL.033 | Overvoltage |
| AL.037 | Parameter error |
| AL.045 | Main circuit device overheat |
| AL.046 | Servo motor overheat |
| AL.047 | Cooling fan error |
| AL.050 | Overload 1 |
| AL.051 | Overload 2 |
| AL.054 | Oscillation detection |
| AL.092 | Battery cable disconnection warning |
| AL.09F | Battery warning |
| AL.0E0 | Excessive regeneration warning |
| AL.0E1 | Overload warning 1 |
| AL.0E6 | Servo forced stop warning |
| AL.139 | Open-phase error |
Evidence to collect
- Photo of the display with the full alarm and detail number
- Alarm history from MR Configurator2
- Amplifier model (-G, -B, -A, W, D) and firmware version
- Servo motor model
- What the axis was doing at the alarm
Work on fuel trains, burners, pressure vessels and electrical equipment must be done by qualified personnel following the manufacturer’s documentation and local codes. Never bypass a safety device or interlock.