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MG3 not driving the motors


Not really installation troubleshooting, but more of support is required.

I had MG3 working fine for something about a year, but recently when I came back to the workshop after leaving it doing the cut job I found out that the K40 laser had stopped mid-job. I had a look at lightburn console and there was an error indicating that the board does not detect 5V and 24V supply. I have rebooted everything with the same commands. Not thinking too hard about it I blamed the PSU and bought a new one as I wanted an upgrade anyway. I went for Cloudray MYJG-60W and a separate 24v PSU.

I have connected MG3 to both power supplies (shared GND between them), and the motor and limit switch connections were unchanged. As soon as I plugged in 24V supply magic smoke came out from the motor driver (A4988). Otherwise, the board was behaving just fine, other than the motors would not spin. I could see the motor LED come on when it was trying to home the gantry, but the motors would not budge. Both LED's for 5V and 24V are ON. I have obviously replaced both A4988 sticks and double-checked the wiring, but the motors still do not move.

Does anyone have any suggestions? Do I need a new MG3 board?

If so, why did it fail?


dancolwp1974 has reacted to this post.

Hi Patryk,

Your judgement to replace the power supply after losing 5V and 24V seems sound to me - I can't think of any 'common fault' that would cause the MG3 to report both power sources missing.

The rest of the description of your new power supplies wired with common ground, replacing stepsticks etc all seems reasonable. Please post a photo of your new power supplies just in case I can spot something with how you've rigged them up.

Hard to say the cause of failure. Perhaps the original power supply went out with a 'bang' and damaged the MG3 at that time. When supplying with new power supplies the prior fault became visible.

Anyway, you've taken responsible and appropriate steps at each stage, so I'll email you directly with a proposed resolution.



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