What the 0x000039 alarm means

A joint brake failed to release or failed its self-test; the joint is locked to prevent the arm dropping. This is one of the most common faults in our repair logs for the JAKA Zu / JAKA Pro cobots (APP) platform, and the first inspection typically locates the cause.

Most common causes

  • Brake power supply or wiring fault
  • Brake worn from age or excessive E-stop usage
  • Joint module internal fault
  • Wrong brake parameter after a module swap
Field note: Field experience says the first cause is the most likely — verify it before moving on to the rest.

Step-by-step field fix

  1. Do not force the joint — support the arm first
  2. Check brake supply voltage at the joint
  3. Power-cycle and listen for the brake click on enable
  4. Verify parameters after any module replacement
  5. Replace the joint module if the brake does not release
Safety first: For JAKA 0x000039, a failed brake means a vertical axis can drop - a person underneath is a severe-accident case, so we require mechanical support first and no repeated power-on trials. The self-serviceable action is Do not force the joint — support the arm first; anything past that falls under a dropping vertical axis and needs a certified engineer. On JAKA 0x000039: the only safe self-action is stopping the axis, holding power off and supporting the arm mechanically; gap measurement, torque testing and brake replacement are engineer work.

How we diagnose brake faults on site

JAKA 0x000039 belongs to the brake family. On JAKA 0x000039 the failing stage is joint-integrated drive modules on the JAKA collaborative robot cabinet - the electromagnetic brake: brake supply, coil, friction lining and mechanical gap - directly tied to whether an axis can drop. We start reading JAKA 0x000039 at the pendant and app alarm pages; codes are hexadecimal with a 0x prefix.

The chain involved in JAKA 0x000039 runs: brake control signal -> brake supply circuit -> electromagnetic coil -> friction lining and disc -> axis holding.

Brake power supply or wiring fault on JAKA 0x000039 is often not the brake itself: A brake that will not release is often not a bad brake but a short supply. The brake needs rated voltage to release fully; burnt relay contacts in its supply circuit, undersized conductors dropping voltage, or a weak supply module leave the brake half-open - it appears to work while actually running on friction, and then it burns. We measure actual voltage at the brake terminals against the nameplate; beyond the allowed drop we chase the supply circuit, not the brake.

Field notes on this page cover JAKA 0x000039 (Brake Fault); written by the Henghuan repair team, updated 2026-10-01.

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Related Brakes alarms

0x000030 — Controller Temperature Too High 0x000031 — Bus Voltage Abnormal 0x000032 — Motor Overcurrent 0x000033 — Encoder Fault 0x000034 — Motor Overtemperature 0x000035 — Collision Detected
Same family: this code belongs to the Brake alarms family - the page collects all Brake-family codes we have handled, with the common inspection order and spares.
Other brands: we also keep field-fix libraries for AUBO · ROKAE · Dobot and more — see the complete alarm code hub.

Frequently asked questions

QWhat does the JAKA 0x000039 alarm mean?

A joint brake failed to release or failed its self-test; the joint is locked to prevent the arm dropping. This is one of the most common faults in our repair logs for the JAKA Zu / JAKA Pro cobots (APP) platform, and the first inspection typically locates the cause. JAKA 0x000039 sits in the brake family; on our work orders the highest-frequency trigger for this code is "Brake power supply or wiring fault".

QCan I clear a JAKA 0x000039 alarm myself?

Whether JAKA 0x000039 clears on its own depends on the outcome of "Do not force the joint — support the arm first". Finish the flow with "Replace the joint module if the brake does not release" to confirm JAKA 0x000039 - do not skip it. If that step is clean, the second most frequent cause on JAKA 0x000039 is "Brake worn from age or excessive E-stop usage". When JAKA 0x000039 keeps coming back it is not a one-off trigger - especially if Replace the joint module if the brake does not release is where you get stuck. Do not keep producing through JAKA 0x000039.

QWith a brake alarm like JAKA 0x000039, can we keep producing for now?

The commonest causes we see on JAKA 0x000039 are "Brake power supply or wiring fault, Brake worn from age or excessive E-stop usage, Joint module internal fault", so we stock the van against those. For JAKA 0x000039 specifically, we carry the brand's common brake assemblies, relays and supply modules; every change ends with a static hold test. For JAKA 0x000039, brake faults carry drop risk so we prioritise them, and after replacement we hold-test on site before handover. Before we roll, tell us what JAKA 0x000039 shows on the pendant and app alarm pages; codes are hexadecimal with a 0x prefix and what the machine was doing - phone or video triage is free.

The content on JAKA 0x000039 was written by Henghuan Robotics service engineers from hands-on repair experience. Alarm descriptions are our own reference summary and may differ by controller or software version — defer to JAKA documentation, or contact us to confirm. Henghuan is an independent service provider with no affiliation or endorsement by JAKA.