The acrid smell of failure in the morning

Having finished all the mechanical stuff, I proceeded to the promised land of electronics. My yet_to_be_named prusa mendel uses RAMPS   1.3 for all of the heavy lifting. For firmware Sprinter was chosen because the "just works"™ feature looks damn compelling. There was one small hiccup trough . Sprinter firmwares Makefile is hardcoded to search for gcc in /usr/bin. Sometimes the distro provided gcc is a bit buggy so it is recommended to use arduino IDE to compile it.

So everything was fine in the evening. Firmware was booting communicating and reading the termistor. I did not connect the 12V power supply yet because stepper testing "might/will" require quick reflexes.

So this morning I decided to start with endstop calibration. I was quite puzzled when the firmware refused to boot and the 5V regulator on the arduino board almost went up in smoke. It turns out that all my pololu a4983 drivers have shorted their power supplies to the ground. I did not have +12 supply connected yesterday, yet I saw no warning in datasheet about not connecting the motor power supply. The most puzzling part is that, I managed to kill all 4 of them in one go. I wonder if the A4983 are so fragile or did I do something extremely stupid.

A bit of debugging on a breadboard confirmed, that all the A4983's are quite dead and show no recognizable signs of life. Oh well that was not even a learning experience, because I have no inkling what killed them.

Plan B


I will scavenge the stepper drivers from my CNC mill and try to use them. Luckily there is a 4 axis driver board on the CNC.

Is it here yet ??? how about now ???

Last  week I decided to join the ranks of the reprap crowd. It turns out that is is quite hard to find "someone near you" to print the plastic when you live in Estonia. To make matters worse thanks to the EU import tax everything coming from outside EU gets taxed the living hell out of.

Luckily I was able to find NOPHEAD's fantastic offering and UK can be stretched to fit the definition of "near you". The parts arrived in just 4 days. Astonishing considering I have been waiting 2 weeks for the electronics.   

Up Next: building the prusa day 1.