What the C57A1 alarm means

A joint brake did not release when commanded; the joint does not move and the controller stops the motion. This is one of the faults our repair team handles on Universal Robots CB3 / e-Series (UR5/UR10/UR16/UR20) systems — the cause is usually identifiable within the first on-site inspection.

Most common causes

  • Brake solenoid or brake coil failed
  • 24 V brake supply wiring broken
  • Mechanically stuck brake from corrosion or contamination
  • Wrong brake release signal routing after maintenance
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. Listen/feel for the brake click when enabling servos on the affected joint
  2. Measure the 24 V at the brake connector during release command
  3. Check brake wiring continuity
  4. Try the manual brake-release procedure (support the arm first)
  5. Replace the brake assembly or motor if the brake is mechanically dead
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 Brakes alarms

C150 — Protective Stop — Position Close to Joint Limits C152 — Protective Stop — Position Close to Safety Plane Limits C153 — Protective Stop — Position Deviates from Path C154 — Protective Stop — Position in Singularity C155 — Protective Stop — Robot Cannot Maintain Position C157 — Protective Stop — Collision Detected
Other brands: we also keep field-fix libraries for Kawasaki · Staubli · Epson and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the Universal Robots C57A1 alarm mean?

A joint brake did not release when commanded; the joint does not move and the controller stops the motion. In field practice it belongs to the brakes family of faults.

QCan I clear a Universal Robots C57A1 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 Universal Robots documentation or contact us. Henghuan is an independent service provider, not affiliated with or endorsed by Universal Robots.