How to Test a Stepper Motor with a Multimeter (Guide)
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A stepper motor is a DC motor that can be "controlled" by a microcontroller, and its main parts are a rotator and a stator. They are used in disk drives, floppy disks, computer printers, gaming machines, image scanners, CNC machines, CDs, 3D printers, and many other similar devices.
Sometimes stepper motors get damaged, causing a continuous electrical path to break. Your 3D printer, or any other machine using these motors, will not run without continuity. So it's important to check if your stepper motor has continuity.
Typically, you will need a multimeter to test the integrity of your stepper motor. Start by setting up your multimeter. Turn the selector knob to the resistance setting and connect the multimeter leads to the appropriate ports, i.e. the black lead to the COM section and the red lead to the port with the letter "V" next to it. Adjust the multimeter by connecting the probes together. Check the wires or contacts of the stepper. Pay attention to the indications on the display.
Typically, if the conductor has a continuous electrical path, the reading will be between 0.0 and 1.0 ohms. You will need to purchase a new stepper rotator if you get readings greater than 1.0 ohms. This means that the resistance to electric current is too high.
What you need to check the stepper rotator with a multimeter
You will need the following tools:
- Stepper rotator
- 3D printer
- The step cable that goes to the printer's motherboard - the coax cable must have 4 pins.
- Four wires in case of stepper motors with wires
- Digital multimeter
- Multimeter probes
- Adhesive tape
Multimeter setting
Start by choosing Ohm on the multimeter using the selection knob. Make sure you have 20 ohms as the lowest. This is because the resistance of most stepper motor coils is less than 20 ohms. (1)
Connect test leads to multimeter ports.. If the probes are not connected to the appropriate ports, connect them as follows: insert the red probe into the port with a "V" next to it, and the black probe into the port labeled "COM". After connecting the probes, proceed to adjust them.
Multimeter adjustment will tell you if the multimeter is working or not. A short beep means the multimeter is in good condition. Just connect the probes together and listen to the beep. If it does not beep, replace it or take it to a specialist for repair.
Testing wires that are part of the same coil
After you have set up your multimeter, start testing the stepper motor. To test the wires that are part of one coil, connect the red wire from the stepper to the red probe.
Then take the yellow wire and connect it to the black probe.
In this case, the multimeter will not beep. This is because the yellow/red wire combination does not refer to the same coil.
So, while holding the red wire on the red probe, release the yellow wire and connect the black wire to the black probe. Your multimeter will beep continuously until you break or open the switch by disconnecting the multimeter leads. A beep means the black and red wires are on the same coil.
Mark the wires of one coil, i.e. black and red, attaching them with tape. Now go ahead and connect the red test lead to the green wire, and then close the switch by connecting the yellow wire to the black test lead.
The multimeter will beep. Also mark these two wires with tape.
Contact testing in case of pin wire
Well, if your stepper is using a coaxial cable, you will need to check the pins on the cable. There are usually 4 pins - just like 4 wires in a wired stepper rotator.
Please follow the diagram below to perform a continuity test for this type of stepper motor:
- Connect the red test lead to the first pin on the cable and then the other test lead to the next pin. There is no polarity, so it doesn't matter which probe goes where. Note the ohm value on the display screen.
- Keeping the probe constantly on the first rod, move the other probe across the rest of the rods, noting the reading each time. You will find that the multimeter does not beep and does not register any readings. If so, your stepper needs to be repaired.
- Take your probes and attach them to 3rd and 4th sensors, pay attention to the readings. You should only get resistance readings on the two pins in series.
- You can go ahead and check the resistance values of other steppers. Compare values.
Summing up
When checking the resistances of other steppers, do not mix up the cables. Different steppers have different wiring systems, which can damage other incompatible cables. Otherwise you can check the wiring, if 2 steppers have the same wiring styles then you are using interchangeable cables. (2)
Take a look at some of our articles below.
- How to check integrity with a multimeter
- How to test a spark plug with a multimeter
- CAT multimeter rating
Recommendations
(1) coil - https://www.britannica.com/technology/coil
(2) electrical wiring systems - https://www.slideshare.net/shwetasaini23/electrical-wiring-system
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