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External 24V PSU Issue - No motor movement


I want to preface this with a thank-you to you guys, the Mini Gerbil has been a pleasure to use for almost a year now.

I have 'upgraded' my K40 to include a 24V 15A PSU, for which I hope to power the stepper motors from. I have wired it up correctly, or so I thought, however the motors do not respond, and do not automatically home upon connecting as normal with my LightBurn setup.

I have tested the PSU with a multimeter, which is delivering the 24V + & - directly to the Mini Grbl board, and the 5V and Laser connections are made directly to the original K40 PSU.

My 5V jumper is placed to USB, and this has been working well for me.

When I wire the 24V connections back to the original K40 PSU everything works as expected.

Any assistance would be much appreciated!


I have given it another go, the external PSU delivers 0.5A 24V to the Mini Grbl, with the stock K40 PSU providing just shy of 0.5A under no load.

I am wondering if there is something I am missing with the wiring?

The only thing I am moving across to the new PSU is the 24V + & - connections.

I notice the motors lock in position when wired with the stock PSU - but they are not locked in position when wired with the new PSU. Could the polarity be wrong?


Now fixed the issue. With the external PSU hooked up I simply needed a common ground connection made between the power supplies.

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