auto bed leveling servo issue in marlin

Hi

I use marlin firmware and I have a small problem with servo positioning.
The auto bed leveling function works fine but the rc servo does not position to the same angle between probes.
I use 4 measuring points, the servo arm sometimes moves to the verical position (as intended) but sometimes turns more/less and I have to correct it by hand.
Unfortunately it is random.

Any idea??

I had problems like this until I isolated my servo wires. I'm using a PC power supply and noticed that I would get issues like this if anything else (fans, lights, anything) were plugged into the power supply. Then I made a little board where I placed a .01uF ceramic capacitor between the signal line and ground, as well as a 4.70uF electrolytic capacitor between the 5v and ground. My jitters and inconsistent servo control went away. Perfect deployment every time, and I can keep anything I want plugged into the power supply, so I have lights and a fan there also. You might check into something similar if you havent.

Edit: Oh, and if you've extended the wires for the servo like I did, I put my little board right at the end of the original servo wires.

Edited 2 time(s). Last edit at 12/31/2014 05:00PM by FA-MAS.