APM
All alarm codes
ALARM 204

Spindle controller malfunction

An alarm occurred at the spindle controller

Controls
T-3, T-32, Fusion 640T, Matrix, Matrix 2
Machine series
Quick Turn, Integrex, SQT

Causes

  1. An alarm occurred at the spindle controller

  2. AD converter is not detecting the one-revolution-Z pulse from the spindle. On older SQT a Hall sensor at the back of the spindle MP scale generates the once-per-rev pulse into the pre-amp; this sensor fails often.

    • Dontreallyhaveanameforum
      Your MAZAKs AD-convertor not detecting one revolution Z signal. U need to either adjust pre-amp that is located in electrical box on the top of main spindle, or (if AD converter is fault) replace AD converter, or remove …

How to clear it

  1. 1

    Turn off the main circuit breaker, then turn it back on. If the alarm is not released, contact Mazak service.

    • HelmanCNCindustry_blog
      Turn off the main circuit breaker and then turn it back on. If the alarm is not released, please contact your MAZAK service representative.
  2. 2

    Open the small electrical box on top of the main spindle and find the pre-amp. Put an oscilloscope on the Z-pulse output. If there is no pulse, the Hall sensor at the MP scale is the prime suspect.

    • Dontreallyhaveanameforum
      First of all find pre-amp, get oscilloscope and check if there is anything on Z-pulse output. May be Z pilse offset drifted away, although I am betting 5 bucks that the hall sensor failed.
  3. 3

    If the pulse is present but offset is off, adjust the pre-amp. If the AD converter card itself is bad, replace it. Otherwise remove the MP scale and swap the Hall sensor.

    • Dontreallyhaveanameforum
      U need to either adjust pre-amp that is located in electrical box on the top of main spindle, or (if AD converter is fault) replace AD converter, or remove the MP scale and replace hall sensor that sends a single pulse p…

Additional notes

Quoted text via search-result excerpt; HelmanCNC returned 403 on direct fetch. — Often co-fires with Alarm 22 'Feedback System Malfunction' when the C-axis tries to engage.

Confidence: high · Auto-promoted to HIGH — cross-verified across 2 independent research runs (research_alarms_2026-05-21_partners, research_alarms_2026-05-21_forums).

First sourced: 5/21/2026