I'm using two stepper motor 28BYG-48 rated for 12V. Those are unipolar motor with 5 wires. 1 Common wire and 4 wire to control the 2 phases. The motor that is getting hot has around 76-77ohm the common pin and the other pins, while the motor that is cool has around 78-79 ohms.
Both motor are wired the same way through uln2003 driver. For my current tests, I was running the motor very slowly. Almost 1 step per second, I'd expect both motors to be cool as the current rarely switch direction.
Is it possible that one motor is getting more power than the other which would explain why one is getting hot.
When I switch motor positions, the motor that was cool is getting hot and the motor that was hot stay cool. My guess is it's a problem with the uln2003 chips.
One other thing, the uln2003 connected to the hot motor is quite cool compared to the uln2003 connected to the cool motor. When there is no activity (no motor switching direction), one of the two motor gets hot progressively.
How can I fix this? What could be actually causing one motor to get excessively hot?
After taking pictures, I realized I mixed up the namings, those are ULN2003 chips. I have l293d chips but they're for other motors.