If you've followed a few posts you'll see that some of us have had issues with the power supplies that were sent with the printer. I'm feeling that my current situation with getting thermal runaway errors is because the power supply cannot keep up with the movements of the printer, run the fans, mainboard, and LCD, and keep the hotend at the correct temperature. I've talked about it but now I'm at the point where I need to build this to get the printer to work.
Here's the BOM:
Mean Well LRS-350 24v https://www.amazon.com/gp/product/B07SQLJG5L
15A 250v switch/fuse/mains connection https://www.amazon.com/gp/product/B07KS2TQ45
14-16 AWG wire https://www.amazon.com/gp/product/B01AO7586O
Here's a render of the case I'm printing to hold the power supply and provide cover for the terminals.


Thingiverse has exploded so I'm not sure where to put my STLs for the moment.
Currently my materials are on order. They should be here this weekend so I'll do the full write up then. Essentially, we're going to put the ground, neutral, and line from the switch block to the corresponding terminals on the power supply. The supply has several rails for 24v out. With 14-16 AWG wire you should only need to run a pair over to the mainboard. The connectors listed are a convenience factor. You'll run the wires internally from the board out through one of the holes for the barrel connectors. Then you'll solder on a connector. The wires will exit from the enclosure and go a length before terminating to the opposite connector. The mosfet system for the heated bed will no longer be necessary and can be removed. The power for the heated bed will plug into the mainboard where the current wires come off to the mosfet.
When mine gets here I'll clean up the STLs with better measurements. This really holds true for the opening for the switch block. I might put some feet on it or make it look cooler somehow. Then I'll post a follow up showing each of the steps.
I am brand new to all this, so take it as nothing more than an educated guess... but perhaps you (we) need to do this PID tuning since we replaced power supplies. Saw it mentioned in Makertech‘s answer to Johannes question around the thermister type change... reading the wiki page, sounds very applicable to our faster head/bed times with the LRS350 power supplies.
https://reprap.org/wiki/PID_Tuning
I have not got any thermal runaways except for that one time I took the bed to 80 for the PETG attempt.
So I've finished the upgrade:
I used XT60 for an interconnect between the power supply and printer:
I crimped some spade connectors on the ends of 14 AWG wire.
I printed https://www.thingiverse.com/thing:4167842/ that @Jay M linked to in his discussion about the LRS-350 https://www.forum.makertech3d.com/forum/assembly-1/mean-well-lrs-350-24v
The bed and hotend heat up a little faster. I should've timed it because it isn't night and day difference, but it is still noticeable.
I'm still getting thermal runaway errors. I've also now swapped out the thermistor and still getting the issue. One thing I noticed is that the thermistor doesn't seem to be too tight when inserted into the hotend. I wish there was a way to pack something in with it so that it held it up against the block to get an accurate reading. That's what I'm now wonder is causing the issue.
Might be too much weight on that one side...