Core One+ randomly restarts about 10-15 seconds after starting a new print
TL;DR: my factory-assembled Core One+ will randomly power off, restart, and resume about 10 seconds after starting a new print. This occurs about 1 in 30 times when starting a print.
I typically use 'skirt' so it won't even finish a full-bed-sized skirt before the machine powers off, restarts, and resumes. You can see a video of this behavior here. (I didn't catch the power-off, but you can see (and hear) it power on, home, then resume at the back of the skirt.)
Unfortunately when I contact Prusa support they say to check the power cable - pretty insulting, frankly.
That's cool the printer resumes right where it left off but why is this happening in the first place?
Any thoughts?
RE: Core One+ randomly restarts about 10-15 seconds after starting a new print
You could search the forum for ESD.
Don't give up with Prusa support, just take a deep breath and get back to them. Their response is not bad - this is a very common failure mode with just about anything electric with detachable power cord. The catch is, it's obvious to some people but not to others. Their checklist serves also the latter 🙂
RE:
If you are printing largish objects, especially with long, fast runs of the print head, static charge build-up on the belt and motors is a problem that has been reported quite often. There is a long thread on this: https://forum.prusa3d.com/forum/postid/752399/
The underlying issue is that Prusa does not reliably ground the X and Y stepper motors. If the paint layer on the CoreXY mounting frame is "too good", the motors remain electrically insulated and a charge can build up on the moving belts and the motors. Eventually it will discharge through the insulation layer with a minimal arc, causing the printer to crash. In your case the crash happens unusually quickly, so it might be a different issue. But it's easy to check:
You can measure with a multimeter whether your motors are grounded. In resistance mode, measure between any of the four screw heads on top of each stepper motor and a chassis ground point (e.g. the screws in the lower front which hold the Z motors). If you measure high impedance, i.e. more than a few Ohm, the ground connection is missing.
The easiest way to ground the motors is via one of the four screws which hold the motor and its mounting block from below the CoreXY frame. Remove the screw, scrape off a bit of paint in the area below the screw head, reattach the screw. For a secure long-term connection, put in a star washer.