This happened at about hour 44 of a 48 hour print. Luckily, my plans to be out of the house this night changed and I caught it before anything else went up in flames. Yes, the controller was actually on fire, not just melted. Only other damage was some black smoke marks on the inside of my enclosure, and melted the thermocouple leads at the controller.
It's a knock off Rex-C100 sourced from eBay.
Note that I have been using this PID controller heavily over the past year, and have replaced the output relay a couple of times without incident, last time a few months ago. Same printer electronics enclosure I have been running all along, with vent holes and fans.
I have also had several print runs that have lasted for 5 full days unattended without issue.
I believe these knock-off controllers have some type of over heat protection as I also have one of these on my filament extruder that would power off when over heated. I had overlooked adding vent holes in my electronics enclosure.
Replaced it with a Mypin TA4, now back to printing, and the Mypin actually seems to have a tighter high\low swing from set temp, +/- 1C, much better than I could get with the Rex, +/- 3C at it's best PID settings.
Just sharing my electronics failure for anyone that may be using a Rex-C100 knock-off.
Edited 7 time(s). Last edit at 09/09/2013 12:57AM by Dirty Steve.