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2 Year Warranty on ALL products
Troubleshooting the Mitsubishi MR-J2S Series: Essentials Before You Replace It
When your Mitsubishi MR-J2S servo drive starts acting up, the first instinct may be to replace it. But not so fast—many MR-J2S issues are solvable with proper troubleshooting, and in many cases, a timely repair can restore full performance at a fraction of the cost. Before you invest in a new drive, here’s what you need to know to make a smart, informed decision.
Why the Mitsubishi MR-J2S Series Still Matters in 2025
Originally released in the early 2000s, the Mitsubishi MR-J2S series remains a staple in legacy CNC machines and industrial automation systems. Known for its precise control, compatibility with older motion platforms, and long-term durability, the MR-J2S is still running in factories around the world.
Even though newer models, such as the MR-J4 series, are available, many engineers prefer sticking with the MR-J2S due to its compatibility, system familiarity, and reduced downtime. However, when problems begin to arise, understanding the root cause is crucial.
Quick Reference: Mitsubishi MR-J2S Alarm Codes and Fixes
| Alarm Code | Meaning | Likely Cause | Suggested Fix |
|---|---|---|---|
| AL.12 | Overvoltage | Power surge, poor grounding | Inspect power supply and grounding connections |
| AL.19 | Encoder Error | Damaged encoder cable or dirty feedback | Clean and check cable connections |
| AL.37 | Overcurrent | Short circuit or mechanical overload | Check load alignment, motor wiring, and brakes |
Common Mitsubishi MR-J2S Issues (And What They Really Mean)
Before scrapping your drive, check for these common failure indicators:
- Alarm Codes: The MR-J2S flashes error codes for issues like overcurrent (AL.37), overvoltage (AL.12), or encoder problems (AL.19). These are often tied to external factors like faulty cables, overheating, or misalignment rather than internal failure.
- Servo Motor Jitter or Inaccuracy: This could stem from mechanical misalignment, parameter drift, or poor grounding—issues that are repairable without replacing the drive.
- Power Supply Issues: Sudden shutdowns or failure to start may be due to worn capacitors, power surges, or corrupted firmware—again, often fixable through targeted repair.
What’s Included in an Mitsubishi MR-J2S Repair?
When you send your drive to Industrial Automation Co., here’s what we check:
- Comprehensive input/output testing
- Capacitor health and board-level diagnostics
- Firmware inspection and reset
- Encoder signal testing
- Motor compatibility verification (when provided)
We also clean, reseal, and test under load before returning the unit, backed by a full 2-year warranty.
Repair vs. Replacement: Which Saves More?
| Factor | Repair | Replacement |
|---|---|---|
| Cost | Lower (40–70% savings) | Higher (plus installation) |
| Downtime | Faster if part is repairable | Depends on stock and install time |
| System Compatibility | Preserves your current setup | May require reprogramming |
| Warranty | 2 years (Industrial Automation Co.) | Varies by source |
Real-World Example: A Repair Success Story
A customer in Ohio sent in their Mitsubishi MR-J2S-60A drive after repeated AL.19 encoder errors caused daily production halts. After a board-level repair and full reconditioning, the drive was back in service within 5 days—saving over $1,000 compared to full system replacement and avoiding the need to reprogram their entire CNC line.
When to Consider Repair
Repairing your MR-J2S drive is often the best first step, especially when:
- Downtime is expensive and you need a fast turnaround
- The system is built around legacy architecture and upgrading would require a complete controls overhaul
- You want to save on costs—repair is typically 40–70% cheaper than buying new
- Your unit is still structurally intact and not exposed to excessive moisture or severe heat damage
Industrial Automation Co. offers certified MR-J2S repair services with a 2-year warranty, rapid turnaround, and free troubleshooting support.
When It’s Time to Replace
However, replacement might be the better option if:
- Your Mitsubishi MR-J2S drive has internal board damage from a fire, flood, or severe electrical short
- You’re upgrading your automation system and want more advanced features like higher resolution feedback or predictive diagnostics
- Parts are unavailable or prohibitively expensive (which can happen with rare variants)
Industrial Automation Co. has a robust stock of Mitsubishi MR-J2S drives, including hard-to-find models like the MR-J2S-40CP, MR-J2S-200B, and MR-J2S-100B, with same-day shipping available.
How to Know Which Path to Take
If you're on the fence, ask yourself these three questions:
- Can the downtime be minimized with a fast repair turnaround?
- Will replacing the drive require reprogramming or upgrading other components?
- Is your current system working well aside from the drive issue?
If the answer is "yes" to any of the above, a repair may be your most cost-effective move.
Talk to a Technician First
Before making a final decision, get a second opinion. Our in-house team can help you evaluate fault codes, symptoms, and compatibility factors—reach out here or call us for personalized support. We’ll help you make the smartest move, whether that’s repair or replacement.
Get Back Up and Running—Fast
With thousands of in-stock Mitsubishi parts and an expert repair team, Industrial Automation Co. helps you minimize downtime and extend the life of your automation equipment. Don’t gamble on guesswork—talk to us today and make the right move for your operation.
Need help with your Mitsubishi MR-J2S servo drive? Get in touch or shop our in-stock Mitsubishi MR-J2S inventory now.