What the A.100 alarm means

An overcurrent flowed through the IGBT power stage or the SERVOPACK heat sink overheated; the servo pack cuts motor power to protect itself. On YRC1000/DX200 this surfaces as a major servo alarm for the affected axis. This is one of the faults our repair team handles on Yaskawa DX100 / DX200 / YRC1000 systems — the cause is usually identifiable within the first on-site inspection.

Most common causes

  • Short circuit or ground fault in the motor power cable (U/V/W)
  • Motor winding short to ground
  • Damaged SERVOPACK power stage (IGBT failure)
  • Ambient temperature above 55 degC or clogged cabinet cooling
  • Excessive load inertia or repeated hard acceleration
Field note: the first item on this list is what we find most often on real machines. Check it before you go deeper.

Step-by-step field fix

  1. Power off, discharge the DC bus, then measure motor cable phases U/V/W to ground for a short
  2. Disconnect the motor and power up the SERVOPACK alone — if A.100 returns with no motor, the power stage is dead
  3. Check cabinet cooling: fans, filters, ambient temperature
  4. Review the application duty cycle; soften acceleration if inertia is high
  5. Replace the SERVOPACK and re-verify with a test jog; back up CMOS.BIN before any board swap
Safety first: never bypass safety circuits or force contactors closed. If the alarm involves E-stop chains, brakes or drive power, and you are not a trained robot technician, contact a professional — wrong moves here can cost you a robot or an injury.

Still stuck? Get an engineer on the phone — right now

Tell us the alarm code, the robot model and what was happening when the alarm came up. Our engineers run these diagnostics every day, and remote diagnosis by phone or video call is free.

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Hotline: +86-20-39029800 · WhatsApp: +86-188-1886-2860

Related Drive & Power Stage alarms

A.320 — Regenerative Overload A.400 — Overvoltage — Main Circuit DC Voltage Too High A.410 — Undervoltage — Main Circuit DC Voltage Too Low A.710 — Overload — High Load (Stall-level Torque) A.720 — Overload — Low Load (Continuous Over-torque) A.7A0 — Heat Sink Overheated (>100 degC)
Other brands: we also keep field-fix libraries for Universal Robots · Kawasaki · Staubli and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the Yaskawa A.100 alarm mean?

An overcurrent flowed through the IGBT power stage or the SERVOPACK heat sink overheated; the servo pack cuts motor power to protect itself. On YRC1000/DX200 this surfaces as a major servo alarm for the affected axis. In field practice it belongs to the drive & power stage family of faults.

QCan I clear a Yaskawa A.100 alarm myself?

Sometimes. Work through the step-by-step checks on this page — the first listed cause is what we find most often in the field. If the alarm returns after two attempts, or the fault involves power, brakes or safety circuits, stop and call a qualified robot service engineer.

QHow fast can a Henghuan engineer help?

On-site response in the Pearl River Delta within 30 minutes to 3 hours, across mainland China in 1-3 business days, and worldwide within 2-5 business days. Remote diagnosis by phone/WhatsApp/video is available immediately.

Written by the Henghuan Robotics repair team from field service experience. Alarm descriptions are our own summary for troubleshooting reference and may vary by controller and software version — when in doubt, check your Yaskawa documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by Yaskawa.