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
XT60 Connectors https://www.amazon.com/Connectors-Replace-Battery-Builder-Hobbyist/dp/B081MQNGR1
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.
Even though I realllllly just want to give up on this printer I might do this mod. I have a leftover power supply from a Monoprice 3d printer I shorted out last year.
Might be too much weight on that one side...
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.
I have not got any thermal runaways except for that one time I took the bed to 80 for the PETG attempt.
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
Dang! Forgot to mention I did that. I haven't PID tuned the bed but I did do the hotend. I don't have the source open Configuration.h since I'm relying from my phone. In that file there is the option to enable the option to PID tune from the menu.
In Configuration.h look for #define PID_AUTOTUNE_MENU it shows on line 486. Uncomment this and you can then go to Configuration -> Advanced Settings -> Temperature -> PID Autotune. I think that's the menu location.
I checked my configuration that I compiled from and see that I don't have PID enabled for the bed. My configuration was based on Makertech's so if it was enabled in their firmware configuration by default then it should be in mine. I might turn it on, but it seems like my bed is holding pretty well.
If you're inclined to enable PID on the heated bed then go to line 514. This starts the heated bed section. On line 531 uncomment the line to enable PID. I don't see a configuration to enable Autotune from the LCD specifically for heated bed. The way the gcode command works is that you run for PID tuning at 200C for the hotend is:
M303 S200 E0 U
This will run the autotune on the hotend at 200C and use the result.
The bed can be done with:
M303 S60 E-1 U
This will run the autotune on the bed at 60C and use the result.
Note, E0 is for the hotend and E-1 is for the bed. The LCD might ask to specify a hotend and bed temp and perform both. If someone enables PID for the bed please post your results.
@Michael G Hmmm. Line 527 is #define PIDTEMPBED -- I'll assume that is what I need to remove comment slashes for. Line 529 is //#define BED_LIMIT_SWITCHING... Not sure how come my line numbers are off from yours. Line 531 is the start of a comment block for me.
I went Googling for BED_LIMIT_SWITCHING, which then led me to reading about PIDTEMPBED, which then made me start charting the bed temp (at least while it sits there idle and not printing. Seems a lot of folks turn this on because their bedtemp swings +/-5C ... I go down to 59.7C turns on and goes up to 60.5C then back down and oscillates right around there for the last 5-minutes or so. I think I'm fine, you can also see how long it took to get to 60C in the graphic.
Going to re-wire with the 16-guage wire tonight, and probably work on Dual Extruder, and getting the Y- and Z-axis as tight as I believe I've gotten the X-axis. Off to do to that now, will probably try to get the bed back to 80C for PETG, and maybe 100C ... will close the basement door in case I get another SHRIEKING runaway alarm. :-)