Error: Z Switch is Broken.

[sbblcift 0]

Hello, with my UM2+ I recently had the issue "Z Switch is broken ER05" although I am pretty sure that my Z switch is okay.
In order to check the HW, I mounted a fully working control board and tested the functionalities. Everything seemed to work perfectly. I assume that my current control board has an issue. I installed Marlin 19 and 17 to test with another FW. The same error. Also did a factory reset unfortunately didn't do much difference. 
I also tried swapping the X-Axis Motor Connection with the Z-Axis Motor Connection. Then the error suddenly turned to "X or Y Switch is Broken" which has made me even more suspicious about a possible SW issue. I also pushed down my heated bed all the way down till it hit my Z-Switch. In this case i received "Z-Switch is stuck". 
Once I tried to move the X,Y and Z Axis manually with CURA via USB I noticed that none of the steppers are actually responding. This seems very weird. Has anyone encountered such problem recently? It didn't look like an HW issue since all the steppers stopped working suddenly. 

Edited July 14, 2021 by sbblcift

[gr5 2,172]

Your Z switch is fine.  It's your Z stepper that isn't moving.

 

When you first home the Z axis it moves the bed down until it hits the switch then up until it doesn't and then down until it does.  If it switch doesn't respond within a certain time then you get the ER05.  If it is always down then you get the "stuck" error.  In both cases, many things of course can cause the error.

 

So to diagnose I need more info.  Do none of the motors ever move?  Did you not notice this back when you were getting the ER05?  When you swapped X and Z motor connection did the X motor start moving but not the Z?

 

Some possibilities:

1) Z stepper driver broken - this is common - these stepper drivers get very hot!  They work hard and can fail

2) Cables to Z stepper broken

3) Stepper broken (almost impossible - this is probably not it)

4) 24V signal to steppers not connected (common - there is a relay, K1, that can block 24V to the heaters and steppers - heat won't work either if this is the issue)

 

These are all very easy to diagnose since the symptoms are quite different.  For example with #4 you can't get the nozzle or bed to heat up.  With #1 you can swap cables to diagnose.

 

If it's #1 and you have an old enough printer then there is an extra driver for the second extruder but newer PCBs don't have that chip installed.  It's pretty obvious since the stepper drivers are a large square chip positioned in a way that they are near and lined up to the 5 stepper connectors.  If you do have an older PCB you can then remap the extra extruder driver in the pins.h file and rebuild Marlin.  I can send you links to more details.  If you have a newer PCB then best course of action is to order a new PCB.

 

 

 

[gr5 2,172]

By the way, it's good you did the factory reset as another possibility is that the steps/mm or the "distance to go before reporting ER05" values can get messed up and factory reset changes these back to defaults.