Rambo Board Y Stepper Failing sporadically after going from 12V to 24V

luke321

Hi all,

I have a rather anoying problem with my Makergear M2 after going from 12V to 24V.
The Y Stepper sometimes does not receive steps, even with very slow speeds, so I am sure it is not a problem of insufficient torque.
I also lowered the voltage and added a fan for cooling.
I changed the stepper driver, and checked all mechanical components.

The sad thing is everything worked fine on 12V, the errors startet with 24V.
I even got the newest Rambo in the meantime (mine was 1.0) and still had failed prints from time to time...

Another curious side fact, I had the same problem on another Makergear M2 with Rambo on 12V at my workplace, but there the problem went away after changing from a PC (Repetier Host) to a Raspberry Pi (Octoprint) for Inputs.

Everythings works fine with Marlin! But for various reasons I'd like to use repetier firmware.
Does anybody have an idea?

Regards
Lukas

Repetier

We had a similar problem with Rumba boards. There it was a design problem that could lead to extra steps from crosstalk. Since firmware is not aware of voltage it is not directly firmware related. One thing influenced by firmware is the motor current set by the digipots. Maybe marlin config had set them to lower value so they did not overheat? Overheat is a typical reason for occasionaly dropouts. If current is high enough even cooling would not help.

An othe rsolution would by to connect Y axis to anouther stepper e.g. second extruder. If you need second extruder as well connect that to y stepper then. If dropouts are short is not as bad as misaligned prints.

luke321

Thanks for the feedback, i suspect some kind of crosstalk too. I will try the second extruder stepper driver, and come back if the problem persists.

luke321

I changed my Y axis stepper driver, but still get the same problem.
Should I try stepper high delay?

Repetier

So you are using the E1 socket now or E1 socket placed in Y?

One thing with Rambo board is that motor current is set in software. Maybe you need to reduce it now that you doubled voltage? If Marlin has lower defaults it would explain that they had no problems. If you go too high the drivers might get hot and disable for short times.

luke321

Yes I was using the E1 socket but know went back to the Y socket because.
I already lowered the current, attached heatsinks to the driver (only the Y socket) and used a 50mm fan.
Drivers don't seem to get too hot, and the error is not repeatable, sometimes I had no problems for 2 weeks, than multiple failed prints in 2 days.