Even if the part cooling fan would cool the nozzle @Sineos screenshot shows that there is no new target temperature being set with the new print job although both files exactly have the same start code with all relevant commands.
But as the homing procedure is performed before the heating of bed and hotend starts this Y homing timeout mentioned in the screenshot is key.
Although this is responsible for the X endstop maybe the CANBus extension board is somehow lost/stuck in communication or badly interacts with the main MCU?
When I check your whole klippy.log there are several homing timeouts for Y and even Z but also timeouts for the MCU.
Sounds like a general electrical topic for me.
Could you maybe post some photos of the electronics and wiring inside the printer?
Just my personal opinion:
I also experimented with the CAN boards: While I appreciated the reduced number of wires, I did not like the added complexity and points of failure.
For myself, I finally decided to go with classic drag-chain certified wires on a toolboard similar to https://www.aliexpress.com/item/1005003688340763.html.
So, while I would claim a solid Klipper / 3D printing knowledge, I can safely be considered an n00b when it comes to the CAN stuff. Fortunately, we have more experienced CANers here
Hmmm, looks like one of my Pi → SKR2 wires has started melting or has somehow been crushed - very odd!. Im going to replace it with some higher quality cabling.
How much current is the wire carrying? To me, it looks like the wire got hot and was touched by something that distorted the insulation. You have a StealthBurner toolhead - is the hot end and stepper current passing through that wire? If so, you’re looking at 2A or so.
Personally, I’m be a lot more concerned about the current passing through the rPi and possibly giving you a ground offset in your system if you don’t have a good common ground between your 24V and 5V power supplies.
When I’ve wired in a CAN bus cable that includes 24V toolhead power, I make sure the +24V and GND are connected directly to the 24V power supply and there is a ground connection between the +24V and +5V power supplies with no chance for any significant current being passed along this connection.
So my printer is still working well after replacing the Pi → SKR serial cable, I’ve printed for over 5 hours so far today and Im on my 4th successful print start (I cancelled the first one after 15 mins as it was just a test print).
