All motors running together

Intermittently I have had a problem with my RepRap where all the motors works simultaneously when using the volume tool and only trying to excercise one of them.

This is on a Generation 2 Ardiuno based system, with breakout board.

This feels like an earthing problem, but I have tried tying all the earths together at the point where they leave the breakout board as there were small resistances present between the earths. Now there is zero resistance left, but still the problem persists.

Anyone hit this kind of problem, and found a solution, or a methodology to trace and fix it?

David

Almost certainly a grounding problem, or a crosstalk problem. Had that myself when I first fired things up.

Make sure your power supply has a good ground setup. I found at one point I was getting a 48 V ac sine wave on my grounds, due to a difference between the laptop's USB ground and the ground on the Reprap power supply. Grounding the chassis on my laptop fixed it for me. Set your multimeter to AC Volts and poke around your grounds while everything is fired up.

For crosstalk, watch your wire routing. Any noise on the "step" wire to the driver board is probably being interpreted as a step command. Make sure you're running the stepper motor wires as far away from the control wires as possible. If they have to cross, try to do it at 90 deg angles. Using shielded, grounded cable can help too.

I'm not sure about your electonics layout, but this is one place where distributing the driver boards on the Reprap frame can help a lot - it keeps the noisy motor wires short and away from the control wires.

Hope that helps!

Wade