Stuttering motor problem

[vsystems]

We've got a chinese laser that worked for about a month, then the one axis started stuttering (press the jog button and it vibrates loudly for about 5 seconds then finally starts to move) through the help of some people on this forum, and after switching some cables around etc. We determined it was the drivers because I connected the known good driver to the axis that was misbehaving and the axis worked normally them. unfortunately, after a few months of waiting for replacement drivers to get shipped in, we now replaced the driver and have the exact same behavior. So this time, I switched the supply of the bad axis to the driver of the good axis and the problem followed suit. So I know it's not the motor, not the driver, and not anything mechanical.. Does anyone have any ideas of what's next to check or replace? or maybe some way to test the electronics to find where the problem is? It's somewhere after the controller (using LaserCut software, I think it's an MCP6515) and somewhere before the driver. please help!
Thank you!

[Al_The_Man]

To decifer, it seems that only when you switch the supply over it follows the supply?
You have separate supplies for each drive then, correct?
If so it would seem that the supply would be the culprit?
What type are they linear - switching? linear regulated? linear unregulated?
Did you try monitoring the supply voltage when it happens?
Al.

[vsystems]

Allow me to clarify, I'm good with electronics, but I don't have much experience with this type of equipment.
So if I connect the power supply that is attached to the Y axis to the X, it still behaves the same, so as far as I can tell, the power supply to the driver is not the problem. I'm not sure what the supplies look like since the cabling is superbly managed and I'm having difficulty tracing it.
I'm not sure if there is one supply for both, but I'm assuming since I can switch the supply lines and have it work, then I should have separate supplies, any suggestions what I should look for?

I'm afraid I don't know what type they are, other than 3 phase motors/drivers I don't know what else I've got. I can provide pictures or video if it helps.
Thank you!

Update: My next guess is the controller itself, it is a MCP6515 and when sending ANY data to the engraver, it has problems engraving properly because of the lack of proper movement on the X axis. The problem occurs also with the jog buttons on the control panel. How can I troubleshoot this?

Update2: I've swapped a whole lot of identical looking cables with each other, tested it and switched them back, I've swapped incoming power to the drivers, it seems no matter what I try the X axis is still bad.

Update3: I found someone with the exact same problem, but on another forum (rockcliff) through the magic of google, but of course no solutions in the forum, or contact information for the person (sigh) Just a vague suggestion that the controller board is "bad". I know it's not the motors or binding since I've successfully tested each motor individually with the known good supply/driver/etc

[zax15uk]

post deleted --- I just read your update3 which seems to indicate you believe it is the controller.

Did you test the motors with the cables in the machine or a spare?

Zax.

[avetek]

I have this issue occasionally and I have yet to track the problem down. I am in the midst of a fairly big production run and am going to try a couple of things after speaking with a techo that i respect. The thought that we had was that it is more than likely a stray voltage or a static build up - In NZ we have an earth on our 240 v plugs and this should be sufficient to ground the machine , but I have to check that the plugs that came with the machine have this third wire. I do remember that the original instructions said that the machine should be independently grounded, but I assumed that this was directed to the two pin plugs systems. I am getting about a 1% error rate but it occurs randomly - it could be the first item or could be the 100th item - no pattern. It was suggested that the Laser tube is a big generator of static and this might be the problem so I am going to double check tonight.
You should also check that the acceleration rates havent changed in you config file .

[vsystems]

Originally Posted by zax15uk post deleted --- I just read your update3 which seems to indicate you believe it is the controller. Did you test the motors with the cables in the machine or a spare? Zax.

I did switch the cables to the motors around and the problem follows the plug, not the motor, so I know the motor is not the problem, not the drivers, and MAYBE not the power supply but I can't totally confirm that, and I don't know much about the controller so I don't know how to test it let alone replace it, it seems to be a very proprietary setup.

[vsystems]

Originally Posted by avetek You should also check that the acceleration rates havent changed in you config file .

I don't believe it's static, since the day it failed, the problem hasn't resolved itself at all, I'm not using Mach3 or any software that I can change config files on so it's nothing I can test there. it's a controller board of some type, I'm unsure what though. It's usb and hooks up to a digital LCD front panel.