April, 2014 | THE MACHINE RUNNER

AC Servo Motor Repair: Encoder Re-Alignment- The Final Step

The expert technicians at RepairZone have a standard process they work through with every repair. While there are multiple steps in the process of an AC Servo Motor repair, one of the final steps are one of the most crucial. This step is the encoder re-alignment.

If correct alignment data of a servo motor is unknown it must be gathered prior to disassembling the motor in order to correctly realign during the assembly process.

When the motor has been disassembled, the encoder must be lined up again so it’s properly aligned with the magnets on the rotor and the windings of the stator.

If the encoder has been replaced, adjustment of the assembly is necessary.

Dynamic alignment (setting while under rotation) of commutation is accomplished by back driving the motor in the forward direction and using an oscilloscope to compare output of generated voltage of the stator/rotor to the corresponding commutation channel.

Oscilloscope traces from the line to line stator voltage and square waveform from the corresponding hall switch represents one phase to phase voltage and one rotor position feedback signal.

Most units will have three position feedback signals that will match up to three line to line voltage outputs.

When feedback outputs are correctly matched with their voltage outputs, then adjusting one set of outputs will also adjust the remaining two.

The RepairZone technicians use manufacturer software and align the encoder to factory specifications. Encoders differ greatly from brand to brand. They are also very fragile and can be quite finicky. After successful alignment, the motor is run-tested for 2-3 hours with a model specific drive or amplifier. Without proper re-alignment, an AC servo motor simply will not work properly.

If you have any questions or need assistance, please call 989-922-0043. To view our Servo Motor Repair capabilities or Servo Motors in Stock at RepairZone, click the appropriate button below:

Servo Motor Repair Servo Motors in Stock

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Test Equipment-Techniques for finding bad components on Printed Circuit Boards (PCB)

Adding diagnostics equipment to enhance your test capabilities is an important part of any electronic repair environment. There are many techniques that can be used to find bad components on a Printed circuit boards (PCB), from a servo drive, or controller. Some of the more common testing equipment are: Multimeters, Huntrons, and capacitors.

Multimeters

A multimeter, multitester, or a VOM (Volt-Ohm meter), is an electronic measuring instrument which combines several measurement functions into one unit. It is used for basic fault finding and field service work, or to measure at a very high degree of accuracy. They can be used to troubleshoot electrical problems in a wide array of industrial and household devices such as electronic equipment, motor controls, domestic appliances, power supplies, and wiring systems.

Digital multimeters (DMM, DVOM) display the measured value in numerals, which eliminates parallax errors, and may display a bar of a length proportional to the quantity being measured. Modern multimeters are often digital due to their accuracy, durability and extra features. In a digital multimeter the signal under test is converted to a voltage and an amplifier with electronically controlled gain preconditions the signal.

DMMs are able to offer as standard the basic measurements that would typically include:

Current (DC) -(Typically low current without an amp probe)
Current (AC)-(Typically low current without an amp probe)
Voltage (DC)
Voltage (AC)
Resistance