Geeetech Prusa I3 M201, X and Y motors shift

[BarryT]

I have a problem when i print for a longer period (around 7 hours). I get a unwanted shift in the x and sometimes the y stepper motors.

I check the voltage on the GTM32+5 A4988 board as in this post:
http://www.geeetech.com/forum/viewtopic ... 13&t=17038

The voltage was to low. And leveld them to 1volt with the screws. After that it did not occure that often. But after printing longer than 6 to 7 hours. It still happens that the x motor shifts. So i get crooked prints.

In the image on the post:
http://www.geeetech.com/forum/viewtopic ... 13&t=17038
It says that the two connections at the top should read 5 volts. But if i measure them i get 3.5 volts. Could that be the problem? And is there a way to adjust that voltage?

Kind regards,
Barry.

[Mark]

" But if i measure them i get 3.5 volts."
this is normal, the voltage of the mainchip for the GTM32 board is 3.3V, not 5V. I guess you can increase the X driver voltage a little and see if it works, or swap the X axis driver with the other axis one, see if the driver is defective or not.

[BarryT]

Thanks for your reply Mark.

I changed them to 1.1 volts and i work a bit better. But after 8 to 9 hours it happend again. I raised the voltage to 1.16 and i did not encounter a shift. So it seems to work. I have not swap any driver yet. I did order a couple of new once so i have some spares.

The strange thing i encounterd is that when i tried to raise the voltage a tiny little bit more. I ended up with 1.6 or higher. I could not get it to 1.2.
Is that normal?

Kind regards,
Barry.

[Mark]

I have ran into the same thing before,I got 1.1V, increase it a little and then 0V...don't know why this happens maybe a defective driver.