Stepper buzz and driver

Hi to all, I'm new in the forum, so thanks in advance for the help.
I recovered from an old printer a bipolar stepper motor, I think that volt necessary is 24V and from section of the cables I think 250mA.. So I'd like to drive with L298 and L297.. I built this circuit and I've connected to 5V and 12V, can I do this? Or I need 24V for the motor? Whitout the stepper, on phases I see 0V 12V 0V 12V, right! in the start condition.. But if I connect the stepper, it begins to buzz, and on phases I see 6V 6V 6V 6V.. Why?

Hi, can you give the diagram which you used, and how you input the controls ( frequentie )
This looks like you hit a current limmit. can you check the current from the 12V supply.
These motors should at least run on the 12V, but don''t be misleaded by the cables, have a look if you can find any product number on the motor, and lat me know.
Rgds, Toin.

Thanks Toinvd, I've solved! 6V are normal in stepper when the start condition is 0101 with 12V supply of stepper.. the problem was ground connection between boards (driver L297+L298 and PIC32 starter kit) and clock speed to high.. thanks to all.
If someone need info about my tests, the stepper PN is: KH42JM2R014B by JAPAN SERVO CO.

Attachment 218880