TOSHIBA TN721 GTN721 Servo Drive Power Supply Module

TOSHIBA TN721 / GTN721 — Every Hour of Downtime Costs You. We Ship Today.

Your servo drive cabinet is dead. The line is stopped. Maintenance is standing by. You’ve already identified the fault: the TOSHIBA TN721 / GTN721 Servo Drive Power Supply Module has failed. You don’t need a catalog — you need a unit on a plane tonight.

We stock the TN721 / GTN721 in Xiamen, China. DHL Express to most destinations in 24–72 hours. No minimum order. No waiting for a quote to be approved by three departments. Send us your shipping address and we move.

URGENT REQUIREMENT? Contact: [email protected] | WhatsApp: +86 18359268345

Quick Technical Datasheet

Troubleshooting & Replacement Tips

After 10 years of field work on TOSHIBA servo systems, these are the failure patterns and swap pitfalls that actually matter on the shop floor:

Common Failure Signatures of a Dead TN721 / GTN721:

• ALM-01 / ALM-04 (DC Bus Undervoltage): The amplifier trips immediately on enable. Measure the DC bus rail at the power supply output terminals — if you’re reading below spec or zero, the TN721 is the prime suspect before you chase the rectifier bridge.
• Intermittent E-Stop with No Fault Code: Capacitor degradation inside the power supply causes voltage sag under load. The drive’s protection circuit trips but the fault clears on reset. Classic sign of an aging TN721 that hasn’t fully failed yet — replace it before it takes out the amplifier board.
• Overheating Shutdown (OHT Alarm): Check the internal fan on the TN721 first. Fan bearing failure is common after 5+ years. The module will thermal-trip before the drive itself shows distress.
• No DC Output, AC Input Present: Blown internal fuse or failed inrush limiter. Do not attempt to bypass — replace the module. Field repair of the TN721 power stage is not recommended without OEM service documentation.

Replacement Procedure — Field Checklist:

• 1. Isolate and lock out the servo cabinet. Verify DC bus has discharged (wait minimum 5 minutes after AC isolation, confirm with meter).
• 2. Photograph the existing wiring harness and connector positions before disconnecting anything. The TN721 has multiple output rails — incorrect reconnection will damage the amplifier.
• 3. Note the DIP switch or jumper configuration on the original unit before removal. Some TN721 variants have address or voltage-select switches on the PCB edge. Match these exactly on the replacement.
• 4. Inspect the mating connectors on the backplane for burn marks or pin corrosion. A failed TN721 sometimes damages the connector housing — clean or replace before installing the new module.
• 5. On first power-up after swap, monitor the DC bus voltage with a meter before enabling the drive. Confirm output is within ±2% of rated voltage under no-load conditions.
• 6. If the system uses a TOSHIBA servo controller with auto-addressing (e.g., axis node ID assigned at power-up), verify the axis map in the controller matches expected configuration after the swap. A replacement module from a different production batch may initialize with a different default node address.
• 7. Run the servo through a slow jog cycle before returning to full production speed. Listen for abnormal motor noise that could indicate a phase imbalance from the new supply.

Firmware Note: The TN721 / GTN721 is a power supply module and does not carry user-programmable firmware. However, if your TOSHIBA servo system requires a firmware version match between the amplifier and controller after hardware changes, verify the amplifier firmware revision has not been reset by the power cycle. Some TOSHIBA drive generations store calibration data in the amplifier that must be re-entered after a cold start following a power supply replacement.

Reliability in Harsh Conditions

The TN721 / GTN721 was not designed for a climate-controlled server room. It was built for the floor — and the floor is brutal.

TOSHIBA’s industrial power supply modules in this series are rated for continuous operation in environments that would kill consumer-grade electronics within weeks. The internal power stage uses industrial-grade electrolytic capacitors with extended temperature ratings, not the standard commercial-grade components that begin to degrade above 40°C. In foundry environments, steel mill auxiliary drives, and coastal manufacturing facilities where salt-laden air accelerates corrosion, the TN721’s conformal-coated PCB provides a meaningful barrier against premature failure.

Vibration is the silent killer of servo power supplies. Loose capacitor leads, cracked solder joints on heavy transformer windings, and connector fretting are all vibration-induced failure modes. The TN721’s mechanical design — with its reinforced mounting points and potted transformer assembly — is specifically engineered to survive the 10–150 Hz vibration spectrum common in press lines, stamping machines, and heavy CNC environments. Units that have been in service for 8–12 years in these conditions and are being replaced as a precautionary measure (rather than after failure) are a testament to the design margin built into this module.

Humidity and condensation are equally destructive. The TN721 is rated for operation in environments up to 90% relative humidity (non-condensing). For installations in tropical climates or facilities without adequate HVAC, we recommend inspecting the module’s ventilation slots for dust accumulation annually — blocked airflow is the primary cause of premature thermal failure in otherwise healthy units.

Global Express Logistics

Our warehouse is located in Xiamen, Fujian, China — one of China’s primary export hubs with direct access to international freight lanes via Xiamen Gaoqi International Airport and Xiamen Port.

How your order moves:

• Order confirmed before 15:00 CST: Same-day packaging and handoff to DHL Express or FedEx International Priority.
• DHL Express: Typical transit 1–3 business days to Southeast Asia, 2–4 days to Europe and the Middle East, 3–5 days to North America and South America. Door-to-door with real-time tracking.
• FedEx International Priority: Available as an alternative carrier for destinations where DHL coverage is limited or where your facility has an existing FedEx account for billing consolidation.
• Documentation: Commercial invoice, packing list, and HS code declaration prepared for every shipment. For destinations requiring a Certificate of Origin, notify us at order time — we can arrange it through the Xiamen Chamber of Commerce.
• Customs clearance: We declare accurate values and descriptions. We do not under-declare for customs purposes. This protects you from seizure risk and ensures your import records are clean.
• Packaging: The TN721 / GTN721 ships in a double-wall corrugated carton with 50mm foam padding on all six faces and anti-static bag wrapping. The 5.3 kg module is secured against movement with foam inserts cut to the module’s profile. We have shipped to 60+ countries without a transit damage claim.

For freight-sensitive destinations or orders of 3+ units, contact us for a sea freight or air cargo consolidation quote. We work with freight forwarders who specialize in industrial automation components and understand the documentation requirements for controlled goods in your region.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com

© 2026 siemensplc.com. All rights reserved.