I built L297 & L298 stepper driver (All same as attached image PLUS a capacitor and var-resistor to limit current).

I attached simple LED to four wires that goes to stepper motor to CHECK the output of signals.

All four LEDs work fine, on, off, on, off....... means, it works fine. But L298 does not turn hot even a bit, I think it should turn hot some bit even without motor.

But When I attach stepper motor wires along with LEDs, then all LEDs keep ON, these all LEDs should work fine with stepper motor as before without motor. So the stepper does not move.

I also tried to adjust the var-resistor, but still it remain same.

Please guide me what may be the reason that the signal output is not good and what is the solution.

Note: I also have build another same stepper driver, it works all fine with and without motor.

 

So you need to do an advanced 'spot the difference' exercise between the one that works and the one that doesn't.

Edit: The chip won't get hot driving only an LED, the current is low.

 

How are your LEDs connected to the four outputs of the bridges? How is each oriented with respect to each output? Are you using series resistors?

 

@ DickCappels

The way, I am using LEDs to four L298 output wires, is attached in image bellow.

@ AlbertHall

Yes, I checked the circuit and got the problem, actually, current limiting var-resistor was not used properly. Now it is working with stepper motor.