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Is my RAMPS at fault?

Posted by saintcady 
Is my RAMPS at fault?
May 08, 2014 01:35PM
Hi folks,

I have a prusa i2 causing me some problems.

My extruder motor started stuttering. That is, when I hit extrude, it kind of twitches and stutters instead on extruding smoothly like it used to. I tried replacing the stepper motor - same issue.
Some online research said that I might have a current problem. Instructions said turn the current down until it won't move, then bring it up slowly until it turns smoothly, then give it a slight turn past that and you should be good. I turned the pot on the ramps board tied to the extruder motor spot all the way, then slowly increased it, but never got to a point where it turned smoothly before I couldn't turn it any more.

Next I tried plugging the extruder motor into the X-axis spot - it worked fine.
I plugged the x motor into the extruder spot - it stuttered the same way.

So far to me this means that part of my RAMPS board is bad.
Does this mean I have to replace the whole RAMPS board?
Anything else I should try first?


Edited 1 time(s). Last edit at 05/08/2014 01:35PM by saintcady.
Re: Is my RAMPS at fault?
May 08, 2014 05:56PM
Disconnect the power from your RAMPS and switch the pololu stepper driver on your extruder with one on another access. Reconnect and see if the axis now stutters. If it does, the pololu is bad and that's the only thing you'll need to replace.

NB: do not disconnect / connect motors from / to your RAMPS with the power on. It will damage the pololu.
Re: Is my RAMPS at fault?
May 08, 2014 06:37PM
you turned the pot while the power was on?.. sounds like a bad driver
Re: Is my RAMPS at fault?
May 09, 2014 10:24AM
Hint: before using another step driver, use a DMM, set one wire to GND and the other on the trip pot.. you should read something below 1Volt. keep that reading for when you put it in its original place.

Then, set it to 0.4V. remove the driver and put it in the E0 socket.. ajust from there.

That way, you wont have to recalibrate the driver when you put it back.

Re: Is my RAMPS at fault?
May 11, 2014 08:09PM
I know this might sound basic, but you may have overlooked whether you can manually push the filament through (system unpowered). A jam or restriction in the extruder can give you the effect you are seeing.
Re: Is my RAMPS at fault?
May 13, 2014 02:17PM
Thanks guys!

I think it's the stepper driver as when I swapped it with the one from the x-axis, that seemed to do the trick. I've ordered new ones - fingers crossed!
Re: Is my RAMPS at fault?
May 14, 2014 02:10PM
We had similar problems using 5$ pololu's.
Ordered new drivers (10$ each), problem solved...!

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