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Haas alarm

173 Spindle Reference Signal Missing

The spindle's reference (one per turn) signal from its encoder was not seen when it should have been.

Stops the machineHaas Classic and NGC controls (mills and lathes)

What it means

The spindle's reference (one per turn) signal from its encoder was not seen when it should have been.

Common causes

  • Spindle encoder cable loose or damaged
  • Failed spindle encoder
  • Belt slipping between spindle and encoder

What to check first

  1. Check the encoder cable connections
  2. Look for coolant at the encoder

Lock out the machine before reaching into it. Never bypass a door switch or interlock to clear an alarm.

When to call a repair tech

Encoder replacement and timing is a tech job.

Repair companies that work on Haas

See all Haas repair

Quick answers

What does Haas alarm 173 mean?

The spindle's reference (one per turn) signal from its encoder was not seen when it should have been.

What causes Haas alarm 173?

Spindle encoder cable loose or damaged. Failed spindle encoder. Belt slipping between spindle and encoder.

How do I fix Haas alarm 173?

Check the encoder cable connections. Look for coolant at the encoder. Encoder replacement and timing is a tech job.

Alarm numbers and text can differ by control model, software version and machine builder. This page is a starting point from people who have worked on these machines, not a replacement for your machine builder's manual.

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