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XYZ Machine Tools Ltd
XYZ Bed Mill Safety, Installation, Maintenance, Service & Parts List Manual
4.4.2
To Check the Motor Encoders
If the motor encoder inside the motor has failed or is not reading the machine will fault out on that axis.
Do the following to verify this problem:
Motor encoder only machines – run Service Codes 100 or 131. This will display on the DRO if the
motor encoder is counting. If the axis does not count, the encoder is not counting. This means
either the encoder or the cable is the problem. Visually check the cable for any problems. If the
encoder has failed the motor must be replaced.
Motor encoder and secondary feedback machines – run Service Code 100 or 131. Both the motor
encoder and Newall scale encoder should count on the DRO screen. The motor value should be
displayed under the Z-axis and the Newall scale under the X or Y-axis depending on which axis
you are doing.
4.4.3
Encoder Counts to Pendant
Before replacing the motor due to a bad encoder, it is a good idea to check the cables that take those
signals back to the pendant. If these signals are not getting back to the pendant then the axis will fault.
Check the following cable connections:
Umbilical #1 and #2 at the cable breakout box
Umbilical #1 and #2 at the pendant
Umbilical #1 carries the X and Y axis signals and Umbilical #2 carries the Z signals.
4.4.4
Moving Problem from One Axis to Another
Another way to troubleshoot a problem with a particular axis is to swap parts from 1 axis to another to
see if the problem moves. If the problem moves then that component is faulty. See the example below.
Symptom – X Axis will not move and faults
This particular problem can happen because of any of following reasons: bad motor, servo driver, or
computer module. In some cases it is not always obvious which component is causing the problem. This
example will help us pinpoint the problem through a trial and error process.
Let’s assume we have narrowed it down to the servo or electrical systems and the Y-axis has no
problems. Let’s also assume it is not an obvious problem like a loose connection. This particular example
was done on a machine with motor encoders only.
Swap these components
Results
Physically switch the X and Y motors
Has problem moved to Y-axis?
If yes, replace motor.
If no, the motor is not the problem.
Note: motors are always replaced with the servo driver.
4.5
Servo Driver
Note: the Servo Driver is located in the black box on the side of each motor. X, Y and Z servos are
identical
Indications:
Problems moving just one axis, including hard turning in one direction.
Objective:
Isolate the problem to the particular Servo Driver
Steps:
1.
Turn off and isolate the electrical supply to the machine.
WARNING!
Do not work with the Servo Driver unless the power is disconnected from the machine. There
is possibility of death by electrocution!
2.
Physically swap the servo module from the axis that is not working to one that is.