My company bought an UM3 before Christmas, and I have been asked to look after it.
Since purchase, I have had an issue using the auto bed levelling. It appears to be using the raise print head lever the wrong way around. Manual calibration works perfectly.
When levelling either head, it pushes the head into the bed with such force that it compresses the bed springs fully. it appears it is trying to calibrate the 1st head, using the sensor on the 2nd. Similarly, when the 2nd head is lowered, it tries to calibrate using the sensor in the 1st head. It's almost as if there is a bit set incorrectly in a configuration somewhere.
The recent firmware update hasn't made any changes (apart from a new issue with network connectivity, which multiple people are having).
I'd really like to get the automatic levelling sorted, as ultimately I am not going to be at my company for too much longer (I'm a placement student). I would need to hand this over to someone, and if they have to manually calibrate every time, this is quickly going to become problematic.
Thank you, SanderG, for your kind recommendation, I respect your opinion.
Anyway I just repaired it, my UM3 ist printing again. Wasn't so difficult, please see my photos and the description.
Both of the wires connecting the capacitive leveling sensor are plugged into contact springs on the sensor, and the other side is plugged into a print head PCB connector. Obviously there is a design problem which leads over time to breaking wires at the sensor side, due to bending the wires when opening the print core cover for changing the print cores.
If you want to repair the broken leveling sensor wires, you got to unscrew the four screws holding the bottom part of the print head.
The bottom part then is only held by the level sensor cable and the front fan cable (the two middle connectors of the four ones).
Disconnect both of them, be careful to not damage the wires while freeing them.
Now that you have the printhead bottom part separated from the printhead, you can disconnect the wires (or remove the broken part of the wires) from the contact springs by carefully opening the inner part of the spring until the wire can be pulled out. Don't use too much force, the contact spring is very delicate! If you bent it away from the middle you gotta bend it back. You might wish to use a magnifier and a pointed tool like a needle for this part of the action.
Un-isolate the ends of the wires and solder them, then plug them back into the contact springs, take care not to reverse them (see pictures). Check that they are tightly stuck in there, otherwise you need to bend the spring somewhat more.
After re-assembly of the printhead (careful with the side fans and their cables) and inserting one or both of the print cores you can start the auto-leveling procedure and hopefully start printing again.