Monoprice Select Mini V2 bed cable re-route through 40mm fan hole by novaguy

Last crawled date: 3 years ago

I had the common bed temp sensor issue with these printers. I repaired the wire and then sought to prevent the issue from happening again. I did not find exactly what I was looking for and decided to make my own. This is a re-mix of https://www.thingiverse.com/thing:2198351 inspired by https://www.thingiverse.com/thing:2376061
There is absolutely no cutting or drilling required for this mod. This works with a few different cable chain models out there. I used https://www.thingiverse.com/thing:611593/ for the ends, but I am actually using a cable chain that a friend had printed for me while my printer was down that I do not know the origin of. I needed 10 links for my application. It would be a good idea to print a few more than 10 just to be on the safe side.
You will probably want to print the fan shroud with supports. If your printer does really long bridging well you may be able to get away with printing it upright without supports, but I did not try.
You will need to provide your own screws to mount the fan to the shroud and the fan opening chain adapter. 2 of the stock stock 40mm fan mounting screws can be used to mount the shroud to the back of the printer. You will also need to locate some screws (fairly short) and nuts to secure the bed mount part. I happened to have everything I needed in loose parts bins that I had around the hose so I do not know specifically what screws to recommend. You should print the parts and locate screws that will work before you try to stall the parts into the printer.
Installation instructions:
Note: Please only install this if you are comfortable working on mechanical and electronic devices. It should go without saying, but you are proceeding at your own risk. Be sure the printer is unplugged and cool before you begin.
Whenever handling wires be sure to not pull too hard on connectors. Also always be sure that all wires are clear when tightening any screw to avoid pinching the wire.
Do not over-tighten screws!
Tools required:
Phillips screw driver.
Something to cut wire ties.
Remove the 4 screws that hold the 40mm fan in place on the back of the printer. You could probably do this later, but I found it easier to do this first.
Set printer on it's back and remove the 6 screws that hold the bottom to the chassis. Take care to support the bottom plate when removing the last screw so that it does not free-fall. You can also rotate the bottom panel 90 degrees (with the circuit board toward the back of the printer) to avoid disconnecting anything.
Locate and disconnect the bed heater and bed thermister wires from the circuit board.
Clip any wire ties holding these two wires in place.
Carefully route the two loose wires through the hole in the top of the chassis. You may need to push the rubber grommet through the hole in order to get the bed heater wire connector through the hole.
Put the bottom plate back in place loosely with just a couple screws and the turn the printer upright again.
Pull the two loose cables through the hole in the top of the chassis until they are clear of falling back inside. Note If you had to displace the rubber grommet to get the wires out of the chassis, you can put it back in place now.
Remove the print bed surface. TIP: If you use a caliper to measure the height of all 4 corners it makes re-leveling the bed a little easier when the printer is reassembled.
Cut the wire tie holding the wires to the underside of the print bed,
Pop the rubber grommet out of the print bed and pull the two loose wires through the hole.
Feed both loose wires through the cable chain opening in the bed mount part and then replace the rubber grommet.
Use some short screws and nuts to secure the bed mount part to the bed.
Re-secure the print bed plate to the printer. Be careful with the angle of the wires where they attach to the underside of the bed. Avoid a sharp angle toward the back of the printer so that the solder joints are not under stress.
Feed the two loose wire connectors through the bottom section of the fan opening at the back of the printer.
Set the printer on it's back again.
Remove the bottom panel like before.
Mount the 40mm fan to the flat side of the shroud (not the side with the notch at the bottom).
Position the printer so that the upper-left screw hole for the rear fan is accessible by hanging just over the edge of your work table.
Feed the wires through the notch in the fan shroud and then line up the fan shroud with the original fan mounting holes on the back of the printer. Note that the notch should point down when the printer is upright.
While holding the fan shroud in place with one hand, use one of the original fan mounting screws to secure the upper-left corner (in relation to facing the back of the printer) of the fan shroud to the printer chassis.
Repeat the last step to secure the upper-right corner of the fan shroud.
Reconnect the bed heater and thermister connections to the circuit board.
Re-position and secure the bottom panel of the printer. When doing this take special care to make sure that the fan is not in contact with any wires. It is much closer to the circuit board and other wires than it was before. Use wire ties as needed.
Gently pull on the bed heater and thermister wires to take up excessive slack inside the printer. Note that the bed should move freely to both stop points without any pulling on the wires. If it does not, then you will need to open the printer back up again and find a different route for the wires.
Secure the fan chain adapter to the back of the printer with two screws. Be sure to not apply too much force as doing so could break the fan shroud since it is not supported from the other side.
Attach cable chain links as needed for cable length.