Stepper Drivers (Salvaged MFP)

[metrologist]

Since I resolved the issues I was having with my Brother MFP I have discovered some stepper motors. I have some stepper motor drivers that are missing and I do not recall what they were, so am looking for something inexpensive from a noteworthy ebay seller. If someone could help advise.

One motor looks like a NEMA 17 size and the others are smaller. I have not gotten into the base yet, but I think there is one or two more that will be OK size. I will also post up the circuits I am getting because there might be drivers already there I can use, although they are looking a bit integrated so far.

Anyway, I still want to pick up a few more good stepper drivers, may around a couple amps for the smaller stepper motors like these. I think they were a couple bucks. Thanks

[metrologist]

The chips I thought would be drivers are labeled SHENDEGEN with some numbers. I cannot find a datasheet for any of them, but one was identified as an ethernet controller. Maybe they are being used for drivers anyway.

I think I found what I wanted anyways, DRV8825. What I bought before was A4988.

[metrologist]

I got the DRV8825 drivers in and set up a simple Arduino program that I've used before, which just varies the speed up and down.

I tried the small stepper labeled 4.9 ohm and I am using a 9V supply for the motor. This motor is about 40mm diameter and 15mm thick. The motor does not run at low speed, but does spin smooth within a certain narrow RPM range. I cannot get it to single step - the shaft twitches hard but does not rotate, and there is a lot of torque. And the motor gets very hot.

Any ideas what I need to change?

[metrologist]

I think its this 12v motor.

http://www.mitsumi.co.jp/latest/Catalog/pdf/motor_m42sp_6nk_e.pdf

I am sending a pulse with arduino and the motor does not move until 1us pulse

[metrologist]

OK, there is a little pot on the driver board that is very sensitive to position. That pot is supposed to just be a current limiter as far as I know, and I recall reading a procedure to measure voltage on some pin and adjust to the voltage for the desired load. I put drag on the motor and adjusted the pot for max torque, which was more like just finding the spot that would make the motor turn.

Now the motor does not get so hot and it turns, up to 6k pps.