I had a short circuit by accident so the LM7805 blow up letting the 12 volt through.

I changed the faulty LM7805 but the Steppers still don`t work so there is something else faulty.

I still can connect to the board with printrun and read the heater temperature.

One of the four pololu`s is getting very hot as soon as i connect the 12V. (dead i think)
Another pololu does have 0,0V on the Vref (also dead i think)
The two pololu`s left do have normal Vref and don`t get very hot.

Is there a guide available how to test a pololu (by voltage or resistor value) and to test where on the sanguino (1.3a) the problem is ?

mfg Chri

I had a similar thing happen to me, took the LM7805 and all stepper drivers out... I think yours might have gone the same way! I don't know of a way to test other than putting them in and trying them but if the voltages read right (as in power and earth) and the heater is being read correctly then I'd assume that the chip is working, so infer that the drivers are blown.

Thinking about it, you should be able to use an oscilloscope to check that pulses are being produced by the chip and measure the enable pins on the stepper driver header.