Y and Z motors not moving.... Why???

Hello all,

I finally finished building my Prusa i3 8" today, connected all wires, and uploaded firmware.

I am at the step to test out the motors and end stops using Pronterface... and I am having some problems.

The first thing I tried (after connecting my computer to the printer via USB ) was to hit the Y home button in Pronterface. I believe the heated bed should move forward until hitting the end stop, but nothing happened.

Then I tried X home button,the extruder started moving to the right until it hit the X end stop, and stopped moving (after it bounced(?) back to the left slightly).

At last, I tried Z home button, and just like Y home button, nothing happens.


I can move the X motor to both direction using the arrow buttons in Pronterface just fine, but I get no response when I hit those buttons for Y and Z.


Just to make sure the connectors for Y and Z motors are not bad, I connected both Y and Z motors (one at a time) on X pins and tried to move it.

I was able to move both Y and Z motors, when they are connected to X pins, using the arrow buttons in Pronterface for X motor. So, I think that confirms the motors are fine (they move when current goes through them) and also their connectors are fine, too.

I tried to adjust the trimpot on the RAMP board (that little screw next to the hit sink) to increase the current for Y and Z motor. I turned the pot in small increment while keep hitting the Y and Z arrow buttons for both directions in Pronterface, but none of the motors moved even after I could no longer turn the trimpot to clockwise (= max current setting).

I think it would actually make more sense if none of the motors moved... I wonder why and how X motor control is working while the other motors are not. Can this be a firmware issue?

Also, if i want to check if it's a simple case of RAMP board not sending enough current through Y and Z pins (even with the max trimpot setting). How can I check it? I'm guessing I may be able to check for some voltage change on those pins... but since there are 4 pins (not a simple case of 2 pin setup for + and -), I am not sure what's the best way of checking it.

Well, anyway, if anyone has seen or heard of any issues like this, or any idea on how to fix it, please help me!

Thank you for your help in advance!

Edited 1 time(s). Last edit at 07/11/2013 07:57PM by Yamster.

Oh, one more thing to add.

My printer has a LCD display. When I hit X, Y, and Z control buttons in Pronterface, I can see the value of X, Y, and Z location/coordinate change accordingly.

For example, if I hit +1 for Y in Pronterface, I can see the Y value goes up by 1 on the LCD, and so on. However, as I have stated in the original post, for X the motor actual moves corresponding to those controls, but Y and Z motor does not move - only their value displayed on LCD gets changed according to my input from Pronterface.

Not sure how important this particular piece of information is, but I thought I would share with you.

Thank you!

Okay, I have some updates:

This morning I have decided to swap out the Pololus, since from all the indications it looks like all motors are fine; Pronterface is sending signals to 3D correctly, and RAMPS is receiving the signals for all axis. In other words, the biggest suspect at this point is the motor driver (Pololu).

So, I swapped the Pololus for X and Y motor (thank goodness for the modular design of RAMPS!). What do you know.. now Y motor is moving but not X motor. After that I tried the same Pololu (the one originally used for X motor) on Z motor, too, and Z motor started moving!

I think I can safely conclude that the I got some faulty Pololus. I also tired the Pololu for the extruder motor on other motors, and that one did not work, either.

In other words, I seems like 3 out of my 4 Pololus are bad. I am glad I have found the problem, but at the same time I find it a little odd that not one, but three Pololus are defective like this. I wonder if I did something wrong and false-fully accusing working Pololus. But then again there isn't much I can screw up with these little guys - as mentioned in my original posting, I have tried various settings with the trimpot. Also, all the other variables are fixed, and the only thing changed in my experiment is the Pololu.

Is it common to have bad Pololus like this? Is Pololu the component the most likely to have a defect?

Anyway, I have contacted the seller (I had bought a kit) and asked him if he can send me replacement Pololus. I haven't gotten any response yet (I just sent out email) but I told him I would be happy to pay for the new Pololus if he wants.

I am 99% sure I didn't break these Pololus - I really didn't have much chance to break them that they just started not working from the very beginning, but then again from the seller's point of view, there's no way to know someone who bought a kit a few weeks ago did something stupid and fried them. So, I think it's fair if the seller has some questions about this situation - having not one, but three defective Pololus in the kit, and I won't be offended by that.

Having said that, if the seller does want to charge me, well, I would like to shop around for it to get the best price. LOL. Does anyone know where I can find reliable Pololus for RAMPS 1.4 at a good price?

Thank you!

The seller has shipped the replacement Pololus to me at no charge.

I bought my kit from Makerfarm, and a number of positive comments I found in this forum about this seller was one of the main reasons I decided to buy a Makerfarm kit. Well, I am glad I did. The quality of the parts, the service, and help you get from this seller is amazing. I highly recommend.

Thank you.

lets start again you have a ramps and what firmware? if marlin are the endstops set up correctly, first of all m119 each endstop to see the status post results and your firmware

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