HOW TO SOLVE PROBLEMS WITH STEPPER MOTOR:

We noticed that at many forums, facebook groups and others, where a large number of beginner DIY enthusiasts gather, the topic of stepper motors, usage and configuration is very often discussed.

There have been many questions on our YouTube channel about problems with the stepper motor. The most common problem is how to connect a stepper motor. This mile stone for many people s prevents them from continuing to work on the project.

If you connect the wires incorrectly, you will usually see one or more of the following symptoms:

• The stepper motor work randomly in the wrong direction (back and forth).
• Sometimes it goes in a certain direction and other times it doesn't.
• The engine vibrates in one place.
• Motor shaky and choppy.
• The is no torque.
• The engine is buzzing loudly and definitely not as we expect - it is humming gently.

In this case, you have several options:

• Check if you have correctly identified pairs of coils.
• Check if all cables are operational (they are not broken and if they are properly connected to the screw terminals).
• Check the operation of the controller.

Check our dedicated video tutorial

Stepper motor connection step by step.

 

STEP MOTOR COIL WIRING CABLE IDENTIFICATION

Stepper motor is a kind of brushless motor.

This motor consists of a rotor with a magnet and two stable coils inside the casing (in this article we use a bipolar motor - 4 wire).

Imagine the coils inside the engine.

It looks more or less like as in the simplified graphics below.

The wires which come out of the engine are marked with yellow, green, red and blue (and this is most often the color we deal with). The coils are those wires which are coiled (brown).

Stepper motor drivers control the motor by switching the power to these two coils.

For the motor to function properly, the motor wires must be connected to the appropriate controller outputs. It happens sometimes that the engine manufacturer changes the colors of the cables or connects them differently as in the diagram that can be found on the manufacturer's website. In such a situation, we have to identify the pairs of suitable wires ourselves. There are several techniques for identifying wires, but the easiest way is to use a multimeter.

STEP MOTOR CABLES IDENTIFICATION WITH A MULTIMETER

Firstly, set the multimeter to the diode test position (as in the graphic below). In order to check if your multimeter is working properly, connect the multimeter probes together. If everything is working properly, the multimeter should beep. When the probes are disconnected, the multimeter should show "1" on the display.

So let's start the testing procedure of our stepper motor.

 

1. Select a random stepper motor wire and touch it with the black / negative probe on the multimeter.
2. Select one of the other 3 wires and touch it with the red / positive probe of your multimeter. You have a 33% chance of finding a pair of a given coil on the first try :). Let's assume, however, that you missed it - see the graphic below where we presented our first, failed attempt.
3. Check another wire.

Keep the black probe with the first cable you choose from the beginning and use the red probe to touch another wire.

As you can see in the graphic below, if we missed the right wire with the red probe again, the multimeter will not make any sound, and the display will still be displayed the number "1".

4. If it failed again, connect the red probe to the last wire, which we have not chosen yet, and here the multimeter status should change. The multimeter may sound a soft squeak, and a different number will appear on the display instead of the digit one.

This number does not matter much, and the important thing is that it reads a small value.

That means that exactly these two wires that make up the coil pair.

Separate them from the others and connect to the connectors of the stepper driver A + / A-

5. Now check if the other two wires are also form a pair - touch one of them with the black probe and the other one with the red probe.

If the wires form a pair, the multimeter will again change the number 1 on the display to a different number / digit, and additionally it may make a soft squeak.

Assuming everything is ok, you can connect this pair of wires to the controller terminals B + and B-.

However, if the multimeter does not change its state, it may mean that you have a damaged multimeter or the engine is damaged (e.g. the wires from the coil of the coil are broken).

In this case, to be absolutly sure that something is broken and you did everything corectly perform the procedure again.

HOW TO CHECK THE STEP MOTOR CABLES WITHOUT TOOLS?

The method with a multimeter is the best, but we are aware that not everyone have a multimeter. What to do if we do not have a multimeter at home?

How to check wire pairs without additional tools?

We will present you here another "manual" method, but we must point out that it does not always have to work.

1. Twist two random wires.

   Start by connecting two random motor wires together - you can just touch them together or twist them. (see graphic below).

   If the interconnected wires belong to one coil, they will "create" a magnetic field in the motor when you try to manually rotate the shaft.

   This will be felt by the increased resistance to turning the shaft, or you may have a slight bouncing sensation. However, if the shaft turns slightly and you do not feel the difference between when the wires are connected together and when they are not, the pair of wires selected do not belong to the same coil.

    

   

2. Test a different wires combination.

   Disconnect the cables you previously selected and connect them into another pair.

   The graphic below shows incorrectly selected wires again, so we do not feel any resistance when rotating the shaft.

    

   

3. Find the correct pair of stepper motor wires

    

   If you did not find a pair in previous attempts, disconnect the wires again and connect them in a different combination. If you did not change one wire all the time (as you can see in the graphics, the yellow wire was previously tested with red and blue wire), then the last attempt with the green wire, for example, should be successful. (If no one cables or motor itself is broken)

   If you feel resistance turning the shaft, you have found a pair of wires for one coil!

   Set them aside, disconnect and connect the other two wires together. - the behavior of the motor should be identical to that of the previously correctly selected pair of wires.

   Now you can connect them first pair with driver A + / A- outputs and second pair with B + / B- outputs