Z Axis End Stop not read

[JohnT2]

Hi,

We have just built the Prusa I3 Pro B printer and we are trying to test the Motor operations.

The X and Y motors seem to function correctly and detect the end stops.

However, the Z motor end stop appears to be undetected. Issuing an M119 G-Code shows that the system thinks it is TRIGGERED irrespective of whether it is pressed or not. Using a multimeter I can tell that the triggered state means electrically open circuit. Unplugging the endstop cable at the circuit board makes no difference which is as you would expect because "triggered" means "open circuit".

We have checked the switch and cable and can identify when the switch is depressed by connecting the multimeter to the back of the circuit board where it plugs in. However, the system appears to not be able to detect this.

When we press the HOME button on Repetier, the Z access motor runs for half a second and moves the head upwards. This is repeated every time we press home, resulting in the head assembly slowly going higher and higher each time. We can manually move the head up and down using individual controls so we know it is the correct orientation. We suspect that when performing the home operation, it simply thinks that it has hit the end stop and then reverses the direction for a short time.

Does anyone have any idea how to solve this and find out where the fault is?

Thanks

John

[jzero42]

Are you sure everything is plugged in properly? Maybe can you do a few photos around the switch and the board?

[TAK]

Is the Z_MIN and Z_MAX connectors opposite?