yesterday I opened up a old broken flatbed scanner device, and removed the stepper motor with two ULN2003A "Darlington Arrays". Well, that thing just don't want to work...
I used the stepper knob example and wired everything in correctly. I unfortunately don't know the pinout of the stepper motor, but it has 6 wires, and both red are the center tap's. That's all I know so far.
Well, here's how I wired everything up:
I know it looks a bit like a mess, but its pretty easy: Pin 8 to 11 from the arduino goes into the ULN2003A Pin 1 to 4 input, and Pin 1 to 4 output of the ULN2003A goes to the stepper motor. The Both center tap wires (red) go to +5V from the arduino.
I used the real colored wires from the stepper motor in this schematic. The colors are: red (2x), Black, brown and yellow.
Okay, the result: everytime I start the schematic, the motor just "wiggles" a bit, or moves very slowly, also wiggling in one direction and can be stoped by just touching it very gently. I also tried using +9V from a PSU to power up the stepper motor. It also just wiggles around, but moves "harder", so it can't be stopped so easily. I tried switching the wires going to the stepper motor, but nothing happens. It just wiggles around or it moves while wiggling.
I am confused as hell, because I ripped of this both ULN2003A chips from the PCB of the scanner, and the stepper motor definately was driven by these chips.
I hope someone can help me out, I don't know what to do.