Mitsubishi / MELSERVO MR-J amplifiers and motors

The letter after the capacity is the interface, and it is the one thing that must match. An MR-J4-40A and an MR-J4-40B are the same power amplifier speaking entirely different languages to the controller.

MELSERVO is on a great deal of imported machinery in New Zealand. MR-J2S, MR-J3, MR-J4 and MR-J5 amplifiers with HC, HF and HG motors.

Reading an MR-J4 order code

Take MR-J4-40A.

So 10 is 100 W, 40 is 400 W, 70 is 750 W, 100 is 1 kW and 350 is 3.5 kW.

The interface letter

The critical character.

These are not alternatives. An A amplifier takes pulse and direction from a PLC output; a B amplifier is a node on an optical motion network and has no pulse input at all.

So substituting one for the other is a control system change, not a parts change. Check the letter against the existing unit.

Other suffixes

The multi-axis amplifiers

A multi-axis amplifier is one part. If one axis fails, the whole unit is the replacement.

Same trade-off as the dual-axis Beckhoff AX5000 on our Beckhoff servo page: cheaper and more compact, and a shared failure point.

MR-J3 to MR-J4 is unusually easy

Worth its own section, because most servo generation changes are not.

So an MR-J3 installation can often move to MR-J4 without recabling or remachining the mount. That is rare and it is worth knowing before quoting a like-for-like J3.

We can supply either. Tell us which you would prefer and we will price both.

The motor equivalents

HF is the J3 generation and HG is the J4 generation. The mapping is direct within each family.

Mitsubishi describes these as similar rather than identical, so confirm the specific model rather than assuming from the family letter alone.

Reading a motor number

Take HG-KR053BG1.

The brake letter matters more than anything else on a vertical axis. A motor without a brake on a lifting axis drops the load when power is removed.

Mitsubishi notes that not all options are available for every motor. So a brake or gear combination that exists in one family may not exist in another.

Oil seal and IP rating

Motors with an oil seal carry a J in the code, as in HG-KR with the oil seal option, and reach IP67.

Without the oil seal the rating is lower. In a washdown or wet environment that is the difference between a motor that lasts and one that fills with water.

Check the existing motor before substituting a standard one.

The absolute encoder needs a battery

The most common avoidable fault on a Mitsubishi servo installation.

An absolute position system retains position through a power cut using a battery. When the battery dies, the amplifier loses absolute position and the machine needs re-homing.

That is a consumable, not a fault. If a machine has started needing a home cycle it never used to need, replace the battery before anything else.

The battery type is specific to the amplifier generation. Send us the amplifier model and we will match it.

The drive recorder is worth using

An MR-J4 feature that most people do not know is there.

The drive recorder function captures machine data around a fault, like a black box.

So when an amplifier trips intermittently and nobody can catch it, the data is already in the drive. MR Configurator reads it out.

That is worth doing before ordering a replacement, because a recurring trip is often the machine rather than the amplifier.

The other diagnostic functions

Machine diagnosis is the useful one for a maintenance conversation. An amplifier that reports rising friction is telling you a bearing or a guide is going, not that the drive is failing.

Tuning and vibration

MR-J4 carries advanced vibration suppression control II, adaptive filter II, a robust filter, auto tuning and one-touch tuning.

So a replacement amplifier can usually be tuned in minutes rather than by hand. One-touch tuning runs the axis and sets the gains.

Worth knowing when weighing a used amplifier against a new one. The commissioning burden is low either way.

Safety rating

If the amplifier is providing a safe stop function on the machine, a replacement must carry the same rating. As always, whether a substitution is valid belongs with whoever holds the machine's safety assessment.

Power range

The interface variants do not all cover the full power range. A high-power axis may only be available in certain interfaces.

The encoder

MR-J4 uses a 4 million pulse per revolution encoder with a speed frequency response of 2500 Hz.

That resolution is why J4 positions more precisely than J3 on the same mechanics. It also means the amplifier and motor encoder must match generation.

The other MELSERVO families

MR-JE is the cost-reduced family, with 1-phase or 3-phase 200 to 240 V supply and a narrower feature set. It is not a substitute for a J4 on a demanding axis.

SSCNET III/H communication cycles run at 0.444 ms and 0.888 ms.

Linear and direct drive

MR-J4 supports linear servo motors and direct drive motors as well as rotary.

And on a multi-axis amplifier the motor types can be mixed, so a rotary motor on one axis and a linear motor on another is a supported arrangement.

If a machine has an unusual actuator, that flexibility is often why MELSERVO was chosen.

What to send us

The full amplifier order code. Capacity and interface letter both matter.

The full motor number, including brake and gear suffixes.

Whether the axis is absolute, since that decides the battery.

Whether the motor has an oil seal, if the environment is wet.

Whether the amplifier carries a safety function.

Amplifier or motor or both. They are separate parts.

Before ordering a replacement amplifier

Read the drive recorder. An intermittent trip is often the machine rather than the drive.

Check the battery if the symptom is lost absolute position.

Check the machine diagnosis output. Rising friction is mechanical.

Check the alarm code. Overload, overspeed and error excessive all point at the machine or the tuning rather than the amplifier.

What we can supply

Current production. MR-J5 and MR-J4 amplifiers across all interfaces, HG series motors, MR-JE economy amplifiers, batteries, cables, connectors and regenerative resistors. Quoted with a delivered lead time.

Discontinued. MR-J3, MR-J2S and MR-J2 amplifiers with HF and HC motors. Surplus and tested used, which keeps an existing installation exactly as it is.

Cables and batteries separately. Often the actual fault.

We buy Mitsubishi servo

MR-J amplifiers and HF and HG motors hold real value, and matched amplifier and motor pairs are worth more together. Keep the cables with them.

MR-J3 and MR-J2S units are worth particular money to plants that want to avoid a control system change. See Sell To Us.

Related

Mitsubishi overview.

For servo from other brands see Allen-Bradley Kinetix, Omron G5 and 1S, Schneider Lexium, Beckhoff AX and ABB MicroFlex.

Send us your order codes

The interface letter is the one that must match. A and B are not alternatives. Quotes in NZD including GST.

Request a quote

Industech is an independent supplier of new, surplus and used industrial automation equipment. We are not an authorised distributor of, approved by, sanctioned by, or affiliated with Mitsubishi Electric. MELSERVO, MELSEC, SSCNET and CC-Link are trademarks of Mitsubishi Electric Corporation. All trademarks, brand names and part numbers are the property of their respective owners and are used here for identification purposes only. Information on this page is for identification and does not constitute a safety assessment.