Problems with L298 and L297 circuit

[mojalovaa]

Dear Please help me, I have a problem with your chips L297 and L 298
I made a mini stepper driver for CNC 3-axis and the one we could not work, working chips that are produced around 2006 and are doing well and that this does not work I bought 3 weeks ago.
When you connect electronics to the output between the D (pinout 2) and for all other outputs (pinout 3, 13 and 14) has a voltage of 9.3V, 1.4V and 0.250 V, as soon as I connect the engine and if there is no signal on the control action between 2 and pinout 3 (1 coil motor) is now live and if you are not supposed to be.
I changed the chips for 5 and 7 L297 L298 chips, but the same thing happens all the time, I ask you for help, the scheme can send you if you are interested in is connected.
Nenad Grujic
nenad_grujic@yahoo.com


Theat is my mail , I send theat mail to ST , please if someone know what is problem , I need help.
Thanks

Regards

[mojalovaa]

Here again the description of the problem we have.
I made a driver cnc with L297 and L298, which worked properly during testing on the Y axis we have burned both chips.
I bought new and replaced, but I always had a Y-axis motor is blocked, I thought it was the chips, a friend sent me a new and again when I have replaced the same problem and the port is always active (+12 V output), percent PCB is burnt down, I made a new plate with only one axis, ordered new parts, put together, and again the same problem, the port is open, take out and put the L297 into an outlet, turn the port open, disconnect the diode from the circuit, weighed again, same problem .
When you turn off the voltage at the plate and measure instruments in the field of semiconductors (diodes) instrument shows the conductivity of the A port to all other ports, I do not know what more to try but I replaced the 4 chip and the same problem, I examined the PCB and I do not see any error, give me please someone can help.