Ignoring End Stops

My mini seems to be ignoring both of the Y-axis end stops and one of the Z-axis end stops. I have verified with a multimeter that all switches are functioning correctly, and have verified that the switches are engaged when at the appropriate end of the axis.

The most obvious example is the Y axis. When sending the “home” command, the bed moves back, eventually hitting the end stop switch, yet it continues moving. At this point the printer starts to make a loud noise like the motor is skipping or grinding.

I’m not sure what to do about this since the switches are fine and are being engaged. It’s like the firmware is ignoring the switches or somehow a set of wires has been cut or unplugged.

What are my next steps?

Swap the Z and Y endstop cable at the rambo board would be my guess. To test that is it, do a Home just the Z axis and trigger one or both of the Y axis endstops and see if Z movement stops.

If it isn’t incorrectly assembled wiring, it would be something wierd in firmware, and you would want to reflash to factory config to fix it.

After getting the Control widow open in Cura, try to home each axis(X/Y/Z), and see if all or none work correctly. Try NOT to go lower than 20MM on Z to insure you do not hit the heat bed glass. The others you should be able to go to max/min stops with no problems. You can use your finger to trigger the Z min end stop as it is moving down.

If those all check out, You can connect to your Mini and test the end stops by using the M119 command in Cura. Try even holding down the endstop by hand seeing if the M119 command says that the endstop is triggered.

Thanks everyone for the great advice!

I decided to start with the M119 command to just figure out what the firmware could see. Both of the X-axis switches and the Z-max switches are reporting correctly. Neither of the Y-axis nor the Z-min switches are reporting at all. I suppose it’s time to take this thing apart and test the switches at the board.

I’ll let you know what I figure out.

Did you figure anything out? If you have not done so yet i would do a continuity check with a mulimeter of each wire and see if one of the wires to the switch broke or if the switches themselves broke somehow (seems unlikely that two would fail at the same time).

I’ve confirmed that there’s no continuity in at least one wire per switch. It makes no sense to me. I’ve ordered the parts to build a new set of wires with the appropriate connectors.

It could be that one of the spade terminals is broken but the wire length is so short that there’s no room to cut one off and replace it. I need to replace the entire wire. So, that’s where I’m at right now.

I replaced the endstop wires and all is well. They were broken inside the insulation close to the middle of the wire. They were pulled pretty tightly and zip tied down. I wonder if that put too much stress on them and somehow caused them to fail.

I have had exactly the same problem on my 2016 Mini. After a year, it began crashing the -Y end stop. Support said try the M119 command to see that the switch is working. All tests show the switches working properly all the time. I decided the -Y switch might have been moved back just enough on the screws to be flakey, so I put some tape on the end wall to give a slight protrusion. Seemed to work for a while, then it began crashing again. Since the mechanics and reporting were working, that implied either the Rambo card is bad, or the firmware or the slicer file.

Finally, I changed the print profile. Voila! It seems to have fixed the problem. It may be a little early to jump up and down, but it hasn’t missed a beat in about 20 starts since then.

Looks like the print profile got corrupted.