SV06 Plus Y-Motor randomly malfunctioning, but only in one direction?

Sovol SV06 Plus
,
1

Hi,

I have the following problem: Completely randomly, my Y-axis motor sometimes does not actually follow the instructions, but only in one direction. This can be not only observed at the homing G-code in prints, but even when using the ‘home’ button on my display. (I have a Sovol SV6 Plus).

Sometimes, it will move to the extremum (Y-) and then to the home middle position (Y+). But sometimes, instead of the long roll in the Y- position, the motor will just do a -±+ short steps instead (and then continue with the Y+ code which will result in the bed ramming the front frame rather than landing in home position).

The issue is, this happens completely randomly, and it started having this random behaviour after 3 years of operations.

I did not change my firmware.

And honestly, I can’t understand what’s happening and why.

So essentially, the Y motor is doing

(-+-+)(++++++++++++++++++++++++)

instead of

(-----------------------------)(++++++++++++++++++++++++)

on homing.

But only sometimes?!

There is definitely no slipping between the cogwheel and the toothed belt, neither slippage between the cogwheel and the axle of the motor, it’s the motor that is doing these short back and forth steps.

I feel very lost.

Any ideas? Suggestions?

2

Check the bed cable is clear of the plate & not under the bed.

3

I’m with @Lion that your problem is mechanical not the electronics.

Does the bed move smoothly with the printer powered off?

4

It absolutely does, in both directions.

However, I’ve found the idler pulley does not spin completely freely, and the resistance could trigger the virtual endstop?

Where to get replacement idler pulleys?

5

These will probally work:

https://a.co/d/69WUJI3

Or Sovol will (most likely) send you one but shipping will be from China.