Extruder Motor Not Working

Hey All,

I recently replaced my extruder head and it required a change in the extruder motor direction. So I swapped the wires for the stepper motor to change the polarity of a coil and now the extruder just jitters instead of working.

If I plug the extruder motor into the x-axis and jog it, it runs fine. Now I know that swapping wires on the stepper motors isn't supposed to be able to damage the board, but I think that in this case it has. Any ideas about how to work out what's blown? Is it the stepper driver?

Also note: the heatbed now powers on when I switch on the power supply and won't respond to temperature controls. Not sure if this is related but it was fine before I tried to reverse the stepper direction.

Swapping the stepper wires around while the board is on will kill the pololu drivers 99.5% of the time.

Ok, then I will need a new pololu driver for the extruder. Can you explain the heatbed issue?

Ok, I swapped the stepper of the extruder for another one (with the board OFF this time ), and it runs fine, I have definitely killed the other one. But the heatbed issue persists...you wouldn't have any idea about that would you?

(Apologies for the double-post)

The FET's are quite sensitive to static damage. Could also have been taken out when the Pololu went.

I would guess the FET for the HBP has died in the on position. Since the normal ones are fairly marginal I would replace it with something better than what was on there orriginaly.

From the reprap irc bot.

"Best mosfets for driving your heated bed: IRLB3813, IRLB8743, FDP8870, AOT240L, CSD18502KCS. These mosfets will run merely warm with NO heatsink and a load current of 10A. They should be good to over 15A with no heatsink according to the worst-case numbers in their datasheets and is also see also [reprap.org]"

Dust,

Thanks for all of your help. I have now replaced the pololu and my printer is working again. I'll look at replacing the power mosfet in the future.