z-axis on sanguinololu 1.3a

Hello

I just assembled my reprap huxley kit with a sanguinololu and all axes are working except the z-axis even the extruder drive is working.
I set the rev pin to 0.4V on the a4988s by turning the potis.
The Vdd pin is set to 4.5V on all stepper drivers and the Vmot pins to about 17.5V so this seems to be correct.

To ensure that the motors are working I switched the z-connector to the y-motor connector on the board.
Then I could turn the z-axis up and down by giving the commands for the x-axis on the pronterface.py software.
The connection between 1a and 1b and 2a and 2b is also proven.

Do you have any more ideas what I can try?

Edited 1 time(s). Last edit at 06/07/2012 05:44PM by ahuxley.

Two things to try:

1. Switch the pololus in your X and Z axis and see if you can now move Z. If so, the pololu is broken!
2. Maybe your endstop on the Z axis is misconfigured, try interrupting the beam (for optos) or pressing the switch (for mechanical) and see if you can move the Z axis. If it moves, your endstops need inverting. You can switch the invert endstops define in your firmware's configuration.h

ok I replaced the z-axis stepper driver with a new one and the movement system works now

but now I have another problem when assembling the heat bed the thermistor fell off and I resoldered it
and the temperature is now a little off but still proportional

So the temperature for the bed is now about 6 Degree Celsius when in reality it is 24 degree Celsius

I have the idea to load a new firmware to the sanguinololu with another settings for the resistor
but when I want to upload the firmware arduino 0022 says

stk500_recv(): programmer is not responding

The solutions from the sanguinololu wiki page do not work in my case
even other versions of arduino like 0023 or 1.00 do not work