Rambo does not power up

Hi all,

I’m in the final steps of finishing MPCNC build (everything purchased from V1) and I went to run the software setup and my Rambo does not seem to power up. I’m using the standard power supply connected as shown in the attached pic. The power indicator lights on the Rambo do not light up when connected to the power supply or USB. Windows does recognize the board and I followed all the instructions to install the Arduino drivers. When I connect via Repetier, the button turns blue at the top and it seems I’m connected but the program cant send instructions to the board or move the motors. The entire system seems dead.

I would think at a minimum the LED indicator on the board should light up if it has the appropriate power connection?

Is it possible that this is a bad board?

Any help would be appreciated.


Windows device



Try the pic again


I power them all up and flash them before shipping so chances are really high you have the wrong port or something, the pic will clear it up


Yeah, the mini Rambo doesn’t get any power from the USB, so your 12V is the first place to look.

I confirmed that the AC adapter is putting out 27v. I actually have two identical AC adapters, one from the original kit and one off amazon. Both output exactly the same voltage. Also, I visibly inspected the fuses and they seem fine.

Here is the Repetier and the windows device list.


Sorry I am 99% sure you have to power the first two ports, not just the first one, the middle one also. I knew it looked odd earlier.


1 Like

Ok, let me try that. Thanks Ryan!

That did the trick. Just completed printing my first crown. I’m super pumped - thanks very much for the help!!

Bummed I missed that the first time around, I need to update the ultimachine boards page with the current info.


Crown looks good.