# Stepper Motor wiring confusion

I have a 6-wire stepper motor. It's a Chinese one (OKI KFL42LL) with a black, brown, orange, yellow, white, and grey wire on it. It's specs are 8.7 Ω and 7.5 degrees/step.

I went through a lot of tutorials to figure out the coils of the stepper motor. Most tutorials say that 3 wires form a coil and we should get 2 different coils by measuring the resistance of the coils.

Going through the tutorials I understand that one set will have A, B, and a centre tap. Resistance between A to B will be maximum and centre tap will make it half. The other coil will have an infinite resistance w.r.t. to the first coil.

In the stepper motor I have, all the pins are internally connected and the resistance between all the poles is about 18 Ω and with centre tap is about 9 Ω. I am unable to figure out the coils, can anyone please help me with some other way to work this out?

Let me know if any other information is needed. Thanks in advance.

P.S: The white and grey are centre tap as their resistance is 0 Ω and they show 9 Ω when connected to others. By programming and permutations I found that yellow and orange connect to one coil; black and brown to another coil. I checked the same with other stepper motor. But, I would still like to know the way to find out.

• Let me know if any other information is needed - a data sheet of the device. Feb 24, 2020 at 13:45
• oki-microeng.co.jp/product/pdf_new/07-KFL42L_uni_EN.pdf This is what I have found. Feb 24, 2020 at 13:46
• Good luck because there doesn't appear to be colour information. Feb 24, 2020 at 14:07
• use a battery to energize the coils one at a time Feb 24, 2020 at 15:34
• @jsotola I have already got the correct coils, but was wondering is there any other way or test to determine it instead of trial and errors. Feb 25, 2020 at 7:06

Based on your tests, this appears to be how the coils are wired.

The center taps are connected internally, which is not a problem if you are using a uni-polar driver, they will be connected anyway. However, you will not be able to use a bipolar driver without modifying the motor.

You will need to do more testing to determine the phasing. If you connect a voltage for testing, it must be weak or current limited. If you exceed the rated current you can burn out the coil.

simulate this circuit – Schematic created using CircuitLab

• yes, this seems to be the case. I have got the coils by programming in different connections and sequence. But it was time consuming, was looking for a method to identify it with multimeter or something. I guess, there is no way to it and there is no article to be found on internet about such a motor. I will have to use it as a 5 wire stepper motor! Thank you everyone.:) Feb 25, 2020 at 7:10