Much much later I almost have a working setup.
After fiddling with the acceleration values in Mach3 and setting the stepping mode jumper to full step i managed to blow an LMD, and yes, that was with a proper heatsink attached (not shown in the photos), and the voltage set to 38V.
I got it replaced and it's working again
The only problem i have now is when I quickly switch directions while jogging,
then it doesn't always change direction.. The indicator LEDs however clearly show the DIR signal changing and all my picsteps behave the same.
Does anyone have an idea why it does this ?
I'm using the 20Mhz firmware without current reduction.
Perhaps changing the opto resistors (now at 420R) to a lower value will yield a direction pulse that is a little longer ?
Some pics attached.