Pololu calibration

I have an 8" I3v. I was experiencing an issue where the steppers were not turning but were making a HMMM sound. I believe I traced it to a failed stepper controller and I ordered some A4988 Stepper Motor Driver Carrier, Black Edition (Bulk, Header Pins Soldered) directly from Pololu, my reasoning being that the stepper board had failed due to heat, and the Pololu 'black' a4988 board would be less prone to fail due to its claimed superior heat dissipation. (I do intend to add active cooling.)

What I am experiencing is that on the axis with the replacement stepper controller is that the step (from pronterface) is substantially larger than sent. I tell it to move 10mm...it moved 20. What is going on? I wouldn't think that it would be voltage.. but what do I know..

Thanks for any tips!

chip kigar

Go and read the specifications for the chips. There are basically two types, one of them will do 32 microstepping and one will only do 16 microstepping. If you have replaced a 32 capable one with a 16 capable one then without adjusting the jumpers it will move twice as far as it previously did.

Maybe that is the other way round, too early in the morning for brain in gear yet but either road up it is the problem you are having.

Hi! I think this link will be a good resource and guide for you to calibrate Pololu. Hope this helps!

Thanks to all for the advice. I changed the jumper on the pololu branded driver and that altered the distance. However, for some reason, the Pololu black acted differently, not sure I can describe how, but, not good. Picked picked up a controller at microcenter (sainsmart) and, with the jumper in the '16' position, I seem to be back in business. It is interesting that everyone seems to point at the same a4988 spec sheet. but perform differently. I need to do more research.

When I was building my i3v last year, one of the stepper driver boards arrived with a broken trimpot. I ordered a Pololu black and it arrived before the warranty replacement from MakerFarm, so the black got installed. I used it in the Z axis location on RAMPS for about a year and noticed no difference from the other drivers in how it needed to be configured.

What electronics suite do you have? The link you provided is for a qty of 5 drivers. Did you try more than one of the new ones?