Y axis step/mm problem

[PanDee]

Hi,

I have a M201 printer. I have a problem with the y axis movement. With the default 80steps/mm setting the y axis moves 20mm instead of 10 mm (does not matter where I control the movement manually, from PC or on the printer). In other words, the max y movement is 100 instead of 200. If I change the step value to 40 steps/mm it works as it has to but during printing after some layers (~10) it looks like it swithes back to 80 steps/mm (the settings remain the same 40). I have stored the memory after every changes and restart the printer. Sometimes (after some printer switch on/off) it works fine with 80 steps/mm setup but at that time during printing after some layers it looks like the y steps/mm changes to 40.... All in all the y axis step/mm value changes randomly, independently what I set up on the printer. I can check the movement by manually control the y via PC or via printer LCD, and either of the above mentioned phenomena experienced.

Things already tested:
- new firmware (1.0.5) installed (2x)
- swap motor drivers (nothing changed)
- shake connectors
- try every combination of setting 40 and 80 step/mm and print, heat bed on/off, printer switch on/off and printing...
- reduced Amax Y to 600
- reduced Vmax Y to 300

This all happened after a 3 months unused period.

Any help appreciated, I have ran out of ideas.

Thanks,

[PanDee]

Do you have any advice?!

[William]

So weird...Are you sure you store memory after the Y step/mm modifying??
And did it work fine 3 months ago?

[PanDee]

Yes it is really weird and annoying...
Yes I have stored the memory after every changes, I took care about this step carefully.
3 months ago It was working fine, previously it had an y layer shifting problem which solved by increasing the motor control voltage to 0.9V.