auto bed leveling servo issue

Hi

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

Hi

Have you solved this problem?

Do you think it's about cable interference?

Yesterday I tried a gcode with only movement commands without heat bed and hotend and worked fine!!!

Today I'm going to test with heated hotend and see the results.

Hi

I disabled the servo delay.

//#define PROBE_SERVO_DEACTIVATION_DELAY 300

So the servo is always turned on. It cause some servo jitternig when the Z axis moves down with low speed for probing.
But now it is much better than it was before. The servo moves to the same position, no manual adjustment is necessary.
I read somewhere on this forum that this jittering can be avoided if we connect a 220 ohm resistance between the "-" and signal cable. But I haven't tried it yet.

http://forums.reprap.org/read.php?1,355600

I noticed the same thing.
When extracting the probe two times in a row however (so two times a M401)
the position of the servo is corrected automatically the second time.
I've changed some code in marlin_main.cpp so engaging the probe is always done twice:
from line 1094 (approx) void engage_z_probe() starts:

static void engage_z_probe()

The whole routine has to be ruin two times, so place the body of the routine between a while loop:

int k=0;
while (k++<2){



}

This seems to be a good fix