HITACHI SJ300TM 3B295619-3 Retrofit-Ready VFD Terminal for SJ300 Control Systems
The HITACHI SJ300TM 3B295619-3 is a retrofit-ready VFD control terminal board engineered for smooth, low-risk replacement of discontinued or degraded control boards within the HITACHI SJ300 series variable frequency drive platform. As legacy SJ300 drives age out of manufacturer support cycles, sourcing a verified, tested replacement board becomes critical to maintaining production continuity. This unit is stocked, pre-tested, and backed by a 12-month warranty, making it the preferred choice for maintenance engineers, system integrators, and MRO procurement teams managing aging automation infrastructure.
Whether you are executing a planned control cabinet upgrade, responding to an unplanned board failure, or migrating a legacy drive system to a more maintainable configuration, the SJ300TM 3B295619-3 provides a direct-fit solution that preserves your existing wiring harness, terminal block layout, and drive enclosure. Compatibility with the SJ300 series control architecture means no firmware re-flashing is required in most standard configurations, and the original PLC program logic interfacing with the drive via RS-485 or analog I/O can remain intact.
Before installation, engineers should verify the power supply rail feeding the control board — typically 24 VDC from the drive’s internal SMPS — and confirm that the terminal block pinout matches the existing field wiring. The SJ300TM board interfaces with the drive’s main control PCB via a dedicated backplane connector; inspect this connector for oxidation or mechanical damage before seating the replacement. Module addressing, where applicable in networked drive configurations, should be confirmed against the original drive parameter backup prior to powering up.
In retrofit scenarios involving communication protocol migration — for example, transitioning from a legacy RS-485 Modbus RTU link to a PROFIBUS DP or DeviceNet topology — the SJ300TM 3B295619-3 supports the standard SJ300 option card slot, allowing integration of the HITACHI SJ-PB PROFIBUS adapter or the SJ-DN DeviceNet option card without modification to the base board. This makes it a practical bridge component in phased modernization projects where the drive hardware is retained but the communication layer is upgraded.
For I/O expansion requirements, the SJ300TM terminal board supports the standard analog input (0–10 V / 4–20 mA), multi-function digital inputs, and relay output terminals consistent with the SJ300 series specification. When replacing a board in a system that also uses an SJ300 remote operator panel or a HITACHI ROP-A remote keypad, verify that the operator panel cable and connector are undamaged before reconnecting. In systems where the SJ300 drive is supervised by a HITACHI EH-150 or EH-A series PLC via a dedicated drive communication link, confirm that the PLC ladder program’s drive status word mapping remains valid after board replacement.
Downtime during board swap is typically limited to the time required for parameter restoration. It is strongly recommended to perform a full parameter upload from the drive using the HITACHI SJ300 PC Loader software or a compatible handheld programmer before removing the original board. This backup ensures that acceleration/deceleration ramps, V/f curve settings, motor nameplate data, and protection thresholds can be restored to the replacement board within minutes of installation. In multi-drive panel configurations where several SJ300 units share a common DC bus or are coordinated by a master PLC, isolate only the affected drive before proceeding to avoid disrupting adjacent axes.
All units supplied by SMARTNEXMSK undergo functional bench testing prior to dispatch, including power-on verification, terminal continuity checks, and communication port validation. Each board ships with anti-static packaging, inspection documentation, and a 12-month warranty covering manufacturing defects and functional failure under normal operating conditions. Stock is maintained for immediate dispatch to minimize lead time for urgent maintenance requirements.
Upgrade Compatibility Table
| Parameter | Details |
|---|---|
| Compatible Drive Series | HITACHI SJ300 Series VFD |
| Replaced Part Number | SJ300TM 3B295619-3 (OEM equivalent) |
| Interface / Connector | SJ300 backplane connector; standard terminal block layout |
| Communication Compatibility | RS-485 Modbus RTU; option card slot for PROFIBUS / DeviceNet |
| Power Supply Requirement | 24 VDC internal (from drive SMPS); verify rail before installation |
| Installation Requirement | Direct board swap; parameter restore recommended prior to power-up |
| Replacement Recommendation | Suitable for like-for-like replacement; no firmware modification required in standard config |
| Commissioning Focus | Terminal wiring verification, parameter restore, communication link test |
| Warranty | 12 Months — covers manufacturing defects and functional failure |
| Pre-shipment Testing | Power-on, terminal continuity, communication port validation |
Retrofit Planning for Existing Automation Systems
A successful SJ300TM 3B295619-3 retrofit begins with a thorough audit of the existing control cabinet. Identify all components that interface with the SJ300 drive: the upstream PLC (commonly a HITACHI EH-150, Mitsubishi FX3U, or Omron CP1H), the HMI panel (such as a HITACHI HI-A series or a third-party GOT1000 touch panel), the motor thermistor wiring routed through the drive’s PTC input terminal, and any external braking resistor connected to the drive’s DB terminal. Document the existing terminal wiring against the SJ300 wiring diagram before disconnecting anything.
In cabinets where the SJ300 drive shares a DIN rail with a 24 VDC power supply module, an input filter, and a contactor assembly, ensure that the replacement board installation does not disturb adjacent wiring. The SJ300 series control terminal board is secured by a locking tab mechanism; release this carefully to avoid damaging the backplane connector pins. After seating the SJ300TM 3B295619-3, reconnect the operator panel cable, the field wiring terminal block, and any option card (such as the SJ-PB PROFIBUS card or an analog I/O expansion card) before applying power.
For systems using a HITACHI SJ300 programming cable (USB-RS485 adapter) and the SJ300 PC Loader software, restore the parameter file backed up from the original board. Verify motor rotation direction, overload protection settings, and frequency reference source selection before releasing the drive to production. In systems where the SJ300 communicates with a SCADA or DCS platform via Modbus RTU, perform a communication link test to confirm that the drive responds correctly to read/write commands from the master device.
Downtime Control During System Migration
Minimizing unplanned downtime during a VFD control board replacement requires preparation before the maintenance window opens. The most effective strategy is to pre-stage the replacement SJ300TM 3B295619-3 board alongside a printed copy of the drive’s parameter list and the original wiring diagram. If the drive’s parameter upload has not been performed recently, schedule a brief planned stop to execute the backup — this investment of 15–20 minutes can save hours of re-commissioning time in the event of a sudden board failure.
During the swap, keep the PLC in a safe hold state rather than forcing an emergency stop that could trigger upstream process interlocks. If the SJ300 drive controls a conveyor, pump, or fan that feeds a downstream process, coordinate with the process control team to place the affected loop in manual bypass before isolating the drive. After the replacement board is installed and parameters are restored, perform a no-load test run at low frequency (5–10 Hz) before ramping to full speed, confirming that the drive’s output current, frequency reference tracking, and fault relay status are all nominal. This staged approach protects the original program logic, preserves HMI screen data integrity, and maintains field control continuity throughout the migration.
Retrofit Support FAQ
Q1: Is the SJ300TM 3B295619-3 a direct drop-in replacement for the original HITACHI SJ300 control terminal board?
Yes. The SJ300TM 3B295619-3 is designed as a direct-fit replacement for the original SJ300 series control terminal board. The backplane connector, terminal block layout, and option card slot are fully compatible with the standard SJ300 drive chassis. No mechanical modification is required.
Q2: Do I need to re-enter all drive parameters after replacing the board?
Yes, parameter restoration is required. Drive parameters are stored on the control board, not in the drive’s power section. We strongly recommend performing a full parameter upload from the original board using the HITACHI SJ300 PC Loader software before removal. If the original board has already failed, parameters must be re-entered manually from a printed backup or the original commissioning record.
Q3: Will the existing RS-485 Modbus RTU communication link work after board replacement?
Yes, provided the communication parameters (baud rate, parity, station address) are correctly restored to the replacement board. After installation, perform a Modbus read test from the master PLC or SCADA system to confirm the drive responds correctly before returning the system to automatic mode.
Q4: What does the 12-month warranty cover, and how is it claimed?
The 12-month warranty covers manufacturing defects and functional failure under normal operating conditions. It does not cover damage caused by incorrect installation, overvoltage, or physical impact. To initiate a warranty claim, contact SMARTNEXMSK with the order reference, a description of the fault, and photographic evidence of the installation. Replacement or repair will be arranged promptly upon verification.
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