L298 smoking

Some time ago posted a message in order to get help to repair a board
with l297/l298 combo. The problem was a short circuit between phases.

I have replaced 3 times the L298 chip without sucessfully result.
If I connect the board without stepper everything looks like OK.
But when I connect the stepper after 2 seconds more or less L298
smokes itself. I am not sending steps at all, only I am giving power
at board.

I have tested diodes and they are OK.
I am begining to suspect of L297. Does it some sense ?

Some advice will be welcome

Thanks in advance