Stepper motor failure, Diagnosis and repair.

We recently had a machine in for repair, the machine in question is a HPC Laserscript 3040.

The customer complained that the laser head stopped moving correctly across the X axis, occasionally it would work but the issue got progressively worse.

Symptoms

When powered on the laser head will either begin to home, or vibrate violently.

Reduced torque, laser head can be physically stopped or moved whilst in operation (not recommended)

Motor will only move in one direction, or direction is reversed

Possible causes?

Stepper drive card has failed

wiring issue between stepper card and stepper motor

stepper motor has failed

How to diagnose and find the root cause?

Using the process of elimination we can quickly pinpoint the source of the problem. We know the problem could be one of two components the motor or the drive card, so lets try swapping the connections for the stepper drive cards and see if the problem moves axis with the drive card, or remains on the same axis with the motor.

In our case the fault turned out to be the motor open circuit across one of the two windings. We verified by testing resistance across the windings using a multimeter.

Whats the fix?

In our case this was a quick diagnoses to a common problem, the stepper motor has failed and requires replacement.

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