Author Topic: A3 Pro X-Axis failure - shuddering - SOLVED  (Read 528 times)

UHF

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A3 Pro X-Axis failure - shuddering - SOLVED
« on: January 26, 2018, 06:49:01 AM »
Hello,

I have a month-old A3 Pro 5500mw with a Mana SE control board. About two weeks ago, the x-axis occasionally seemed to go off-course and shudder. Now it does it all the time as it tries to move. If I use x-axis jog in software, it goes one direction and then swaps to the other when I jog again, making a jerky, juddering as it does so.

I've tried LaserWeb4 and LaserGrbl on two different computers - it isn't a software problem. I've swapped the A4988 stepper driver modules over x->y, y->x and tried an identical module from another CNC shield - this doesn't appear to be the problem. In fact the board is quite simple - a problem with the Nano? I put a meter on the caps and resistors, they appear fine but are still in-circuit. Any ideas? The stepper motor? I'm about to ask Banggood for a replacement Mana SE board, but fixing myself is preferable to waiting.

Thanks.
« Last Edit: January 28, 2018, 04:06:38 PM by UHF »

UHF

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Re: A3 Pro X-Axis failure - shuddering - SOLVED
« Reply #1 on: January 28, 2018, 04:09:03 PM »
Bad connection to x-axis stepper. These types of connector do work themselves loose and this will cause erratic behaviour, it seems. First rule of troubleshooting - always check the boring, trivial things first. Just a couple of hours wasted blaming the control board, but at least I learned something about it.

rpt007

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Re: A3 Pro X-Axis failure - shuddering - SOLVED
« Reply #2 on: January 29, 2018, 10:16:38 AM »
In the worst case this can fry your stepper driver due to inductive kickback. Because it is possible that one of the lines will disconnect first, the inductance on the line still connected can lead to dangerously high (or low) voltage levels and the other side of the free wheeling diode has nowhere to recirculate current through. This can cause a very quick voltage spike that can blow out the output MOSFET(s) of your A4988.
Do you have already thought about a solution yourself or is a part of the problem sitting in front of the screen?