OctoPrint disconnect fix (SerialException) by Mikael70

Last crawled date: 3 years, 4 months ago

I have been plagued with disconnects (SerialException) for a long time and I think it is finally fixed
The following did not help:
Improved WIFI connection between router and Pi.
New short USB cable (0.5m)
Ny PSU till raspberry pi
Pi Zero W replaced with Pi 3B
Two chokes rated 30MHz to 600MHz from Kjell & Company on USB cable
One chokes rated 30MHz to 600MHz Pi3 power cable
Five chokes rated 30MHz to 600MHz on Ender power cable
One choke rated 30MHz to 600MHz on 12v cable from Ender PSU
And a lot of other things…
This worked:
Moved printer from the kitchen stove to living room (different fuse)
8.5m extension cord from living room to kitchen (this is NOT a safe way do it)
8.5m extension cord (5.9m was not enough) from problematic outlet in the kitchen
3.2m extension cord of which 2.5m was rolled up in a coil hold together with a shoe lace (dia ~110mm).1.6m extension cord rolled up in a coil (8 turns) dia ~50mm with this 3d printed bobbin
Probably better ways to solve this (Cheapest to most expensive):
Low frequency chokes/ferrites on Ender PSU cable*
General Purpose Filter (Like RES10F10) (not sure if there is an earth passthrough)
Isolation transformer (don’t know how to install this)
UPC (expensive but easy to use)
Wurth has a good homepage for chokes/ferrites. I picked some that I think is good:Wurth
I probably put two 7427729 on each end of the Ender PSU cable and one on the cable feeding the outlet. I think one is enough but I want to make sure it works. Some ferrites are clip-on versions so they are easier to install. The performance of a ferrite is greatly improved if you feed the cable through the hole many times but I think it’s not that practical.
I don’t know the problematic frequency but, in my case, it is well below 30MHz.
I’m NOT an electrician so make sure you ask someone with the right credentials before you change anything. I do believe that making few turns on your extension cord is perfectly safe as long as you don’t make too many turns and not use too much power.
How did I found out?
I noticed a disconnect occurred when I changed the fan speed on my kitchen hood. It was somewhat repeatable (About 10% chance). I believe that the cooler, freezer, microwave, washing machine and so on also can cause this.
I got help from elektronikforumet.com to solve this. Thanks MadModder, grym and gkar!
Please leave a comment if you know more about this.
(I did this 2020-10-12 and it still works fine 2020-11-08)