The MR-J2S-700A is Mitsubishi Electric’s 7 kW MELSERVO-J2 Super series servo amplifier for 200 V three-phase AC power supply with pulse train position command input — the highest-power standard single-unit model in the MR-J2S-A sub-series, providing 7 kW continuous servo control at 37 A for HC-SFS702 and HC-RFS703 series servo motors in active J2S-based heavy-duty servo systems where direct maintenance replacement of failed units is required. In stock at Atlantech Drives. Request your quote within 24-48 hours with worldwide shipping and 12-month warranty.
What Is the MR-J2S-700A?
The MR-J2S-700A is a MELSERVO-J2 Super series servo amplifier providing 7 kW (7,000 W) continuous output power — the maximum standard single-unit power in the MR-J2S-A pulse train series — for Mitsubishi HC-SFS702, HC-RFS703, and equivalent 7 kW servo motors with the J2S-era serial encoder. At 37 A continuous output current with 111 A peak (3×), the MR-J2S-700A was specified for the most power-demanding single-axis pulse-train-commanded servo applications of the J2S era: large horizontal boring and milling machine primary feed and table rotation axes, large-format material handling gantry drives, and heavy-payload robotic systems where 7 kW continuous servo power provides the sustained torque required at rated speed under full load. Three-phase 200–240 VAC supply is required exclusively for the MR-J2S-700A — at 7 kW and 37 A continuous output, single-phase operation is neither rated nor appropriate. The amplifier accepts position command pulses via differential RS-422A or open-collector input at up to 500 kpps, communicates with the legacy MR Configurator software via RS-232C, and does not include any built-in STO safety function — an external safety contactor rated for 37 A at 200 VAC is required for safety compliance. The MR-J2S-700A represents the most difficult to source and most critical to proactively manage of all MR-J2S-A models, given its high power level, limited installed base compared to lower-power models, and the significant production disruption that a 7 kW axis failure causes.
Key Technical Specifications
- Model: MR-J2S-700A
- Rated Output Power: 7 kW (7,000 W)
- Power Supply: 200–240 VAC three-phase only, 50/60 Hz
- Continuous Output Current: 37.0 A
- Maximum Output Current: 111.0 A (3× continuous peak)
- Compatible Servo Motors: HC-SFS702, HC-RFS703 (J2S/J3-era motors)
- Command Interface: Pulse train input (open-collector or differential)
- Maximum Input Pulse Frequency: 500 kpps (differential), 200 kpps (open-collector)
- Encoder Interface: Serial encoder (J2S-era HC motor encoder protocol)
- Safety Function: None built-in (external safety contactor required)
- Regenerative Brake: Built-in, external regenerative resistor connectable
- Communication: RS-232C (MR Configurator legacy software)
- Operating Temperature: 0°C to 55°C
- Dimensions (W × H × D): 170 mm × 260 mm × 195 mm
- Weight: Approx. 5.5 kg
Compatibility & System Integration
The MR-J2S-700A is compatible with any host controller providing differential RS-422A or open-collector pulse train output at up to 500 kpps — Mitsubishi QD75MH4 and QD75D4 MELSEC-Q positioning modules, FX2N-10PG and FX3U-2PG compact PLC positioning modules, and third-party CNC and motion controllers with pulse output. The amplifier’s RS-232C port (9-pin D-Sub) connects to the legacy MR Configurator software for parameter access and auto-tuning — a PC with a native RS-232C port or a USB-to-RS-232C adapter (FTDI chipset recommended for industrial software compatibility) is required. Current-generation HG-SR702 and HG-RR703 servo motors (MR-J4 standard) are not compatible with the MR-J2S-700A — the J2S encoder protocol is specific to HC-SFS and HC-RFS motors, and no MR-J4 era motor encoder can be read by the MR-J2S-700A. The external safety contactor for the MR-J2S-700A must be rated for the motor’s full operating parameters — at 37 A continuous and 111 A peak, an AC-3 duty class safety contactor rated for at least 40 A at 200 VAC is required, with the make current rating verified against the 111 A motor peak. For multi-axis panels where the MR-J2S-700A shares an AC supply with lower-power MR-J2S amplifiers, size the supply bus for the sum of all amplifier rated input currents with a 25% margin — at 7 kW and 200 VAC three-phase, the MR-J2S-700A draws approximately 25 A per phase at full rated load.
Replacement & Upgrade Notes
The MR-J2S-700A is among the most difficult MR-J2S models to source from the aftermarket due to its high power level and relatively limited installed base — fewer units were sold at 7 kW compared to 1 kW and 2 kW models, resulting in a smaller available replacement pool. For facilities with MR-J2S-700A units in critical production equipment, maintaining at least one spare unit in inventory is strongly recommended — sourcing a MR-J2S-700A for emergency replacement can require lead times of 4–12 weeks from specialist suppliers, during which the affected machine must remain idle or operate on a degraded basis. The upgrade to current Mitsubishi servo technology requires simultaneous replacement of both the MR-J2S-700A amplifier (→ MR-J4-700A) and the HC-SFS702 or HC-RFS703 servo motor (→ HG-SR702 or HG-RR703), along with new encoder cable, potentially updated motor power cable, and complete servo re-tuning from factory defaults using MR Configurator2. The MR-J4-700A provides 22-bit encoder resolution versus the J2S base resolution, built-in STO safety function eliminating the external contactor requirement, AVSC II dual notch filter for superior resonance suppression, and the same 170 mm housing width as the MR-J2S-700A enabling direct panel retrofit with compatible mounting. For facilities planning MR-J2S-700A fleet migration, the total project cost per axis (amplifier + motor + cables + commissioning + production downtime) should be evaluated against the risk-adjusted cost of continued J2S operation — at 7 kW, the production impact of an unplanned axis failure is proportionally greater than for lower-power axes, strengthening the case for proactive migration.
Frequently Asked Questions
Q: What external regenerative resistor is required for the MR-J2S-700A on a large machining centre primary axis with frequent rapid traverse deceleration?
A: For a 7 kW axis with frequent rapid traverse deceleration (10–20 cycles per minute from maximum rapid speed), the MR-J2S-700A’s built-in regenerative resistor (approximately 30–40 W continuous capacity) will be significantly exceeded. An external regenerative resistor with at least 200 W continuous power rating is typically required — verify the specific resistance value (typically 13–40 Ω for J2S 7 kW models) in the MR-J2S-700A hardware manual before ordering. Install the external resistor in a well-ventilated location away from heat-sensitive panel components, as a 200 W resistor generates substantial local heat during frequent deceleration cycles.
Q: Can the MR-J2S-700A be serviced by replacing only the DC bus capacitors without full amplifier replacement?
A: Yes, DC bus capacitor replacement is technically feasible in the MR-J2S-700A and is offered by Mitsubishi authorised service centres and qualified independent servo drive repair specialists. The repair requires correct capacitor specifications (capacitance, voltage rating, ripple current rating, ESR specification) and functional load testing after replacement to verify DC bus voltage regulation and ripple current performance. For a 7 kW amplifier where a replacement unit costs significantly more than a lower-power model and sourcing a replacement may take weeks, the repair option is particularly worth evaluating as an alternative to full unit replacement when the failure is confirmed to be capacitor-related.
Q: Is the MR-J2S-700A compatible with the same SSCNET positioning modules as the MR-J2S-700B?
A: No. The MR-J2S-700A uses pulse train input (no SSCNET interface), while the MR-J2S-700B uses SSCNET III optical fibre input. The MR-J2S-700A is controlled by pulse-generating positioning modules (QD75MH4, FX2N-10PG, FX3U-2PG), while the MR-J2S-700B is controlled by MELSEC-Q Q172DSCPU or Q173DSCPU SSCNET III motion controllers. The two variants are not interchangeable from a host controller perspective.
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