Rambo Stepper driver issues

I have used the Rambo board before with no issue but it seems now I am having problems. The board boots fine, but steppers wont move. They can be moved by hand so the are not stuck or frozen. You can run a job and the board acts like its doing the job but no stepper movement, if the system is off and you move the steppers the screen lights up so I know the fuse is fine. Could the reason be that an endstop was hooked up wrong before? Could it kill the drivers? I have ordered a new board to be on the safe side but are there any other reasons for the steppers to act this way?

I would take out the two tiny fuses and double check them. Double check the power that is to the steppers.

If all the steppers are not working it really points to a power issue.

I tried that kinda not sure if the method is sound, i couldn’t find my multimetter so i just removed the fuse, system off of course, pushed the stepper by hand and no power generation lighting up screen. Then replaced the same fuse pushed it again and screen lit up. Not sure how effective this is at finding a bad fuse but…

Try swapping them just to be sure.

Here is a picture of the Rambo board including the fuses called out. F2 is for the motors, and Ryan was suggesting swapping F2 and F3. If you have any way to check for 12V, there are a couple of pins you can use. In the very bottom right of the board, just above the mounting hole, are a ± pair of 12V pins. If you have power to these pins, then you have power on the motor rail. Here they are called out in yellow:

ok so there is power, I used a 12v cooling fan. So what else would stop the steppers from moving?

Im running duel endstops so is the wiring the same IE left to right, red green yellow blue? and if the steppers are not wired correctly would that stop all the steppers from moving?

More data points, So on boot up I get flashing question marks on x, y, z, also I started a job just to see if there was any change and it switched to 2 flashing question marks per axis.

I get a single flashing question marks for any axis I’ve not homed. I don’t remember getting a double question mark. Sorry that I don’t have any ideas on why the stepper motors are not moving beyond checking power on the motor rail.

Question marks don’t mean anything.

You can check with the ohm setting on the multimeter. It should be near zero when out of the system.

It works! Ok the power supply was the issue for some reason I had a 40v 1800 mah power supply when it needed a 12v 6a I found an old 12v 5a and it works.

At 40V, I’m surprised that you did not have issues when you tested the motor rail with the fan. I’m also surprised that the 5V voltage regulator on the board handled 40V. The UltiMachine site list 10V to 24V for supply voltage for the Rambo board.


I guess im just stupid lucky. lol The Rambo is a tough board.

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I was curious about why you did blow the regulator and did a bit of research. According to the schematic, the Rambo board uses a LM22675 as a step-down voltage regulator. According to the datasheet, the absolute max rating is 43V, so your 40V was just under the max.

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