I case this helps someone else …
Klipper recently began shutting down with the following ‘rather long’ error message :
Klipper has shutdown. MCU ‘extra mcu’ shutdown: Timer too close.
This often indicates the host computer is overloaded. Check for other processes consuming excessive CPU time, high swap usage, disk errors, overheating, unstable voltage, or similar system problems on the host computer.
This only happened toward the end of printing runs.
After a few attempted fixes … which didn’t work … I focused on the temperature issue and appear to have ‘fixed’ the issue by:
removing the aluminium cover / fan and psu cover from underneath the machine
purchasing a 160CFM fan and focusing the output directly onto the electronics area (by cutting a suitably positioned hole in the worktop and mounting the fan from underneath pointing upwards).
This has reduced the mainsail reported host / mcu temperates down to an average of 40c and 29c respectively (from 60 / 50 respectively). A big big difference. I have now completed over 18 hours of continuous printing without a glitch.
I hope this helps someone else who may be experiencing the same issue.
On the SV08 the “extra_mcu” is on the toolhead board.
The root cause if your issue was most likely interference on the USB communication lines from the main board to the toolhead. While working on you machine you moved the wires a few mm and lowered the interference.
As said by Caradoc, there is a kown issue related to the communication with extra mcu (over usb). That is not well identified yet. Some people said that is the noise, some others a bad power management, … my own guest is that is related to the heat… that is probably a mix of that or something else.
Many alternative toolhead for SV08 are provided with an additionnal fan dedicated to the PCB side. Probably a good idea but i did not tested yet.
PS: Removing the plate bellow the printer is dangerous. I did it too (to change the main power supply) but we have to replace it to avoid security issue. If you drop something bellow the printer and look for it with your hand, there is a possibility that you can touch the 110/230V cables. To be honnest that should not happen (there is others securities) but this possibility should not be acceptable.
Ah-ha … the EMC thing is a failure mode I hadn’t considered … but a valid one. So … I may have fixed the problem … completely by accident !
Will keep eye on forum for more news on that score.
The issue relating to greater exposure to mains voltage is noted. I used to be an electrician … so am always cautious when sticking hands in places … but you’re absolutely right … it’s not ideal and not recommended for safety sake. A case of don’t do as I do …
Thanks everyone for the feedback. Always appreciated.
Keep in mind the main switching power supply has noise on the output. The PWM switching creates “back EMF”. Those wires are held parallel with the USB data line by the cable sheath creating a low efficiency transformer. USB is a single ended signal…
The wonder of a dancing bear is not how well it dances, but that it dances at all.