Ender 3 V2 USB interface replacement (USBC CH340N)

Description

# Ender 3V2 USB Replacement. The MicroUSB port on the front of my 3V2 has been sketchy for years. Recently it got worse, so I found a solution. With a $3 part and some simple (but small) soldering, I now have a USBC port that works the same way as the MicroUSB port at the front of the printer. Actually, the port at the front of the printer still works - this mod doesn't disable it. I imagine trying to connect to the printer from both ports at the same time wouldn't work though. I did this for myself, but I'm writing it out here as instructions for anybody else who wants to try it. Obviously, if you're soldering stuff to your mainboard, I take no responsibility for anything that might go wrong. This has been working for me, who knows if it'll work for anybody else. # What you'll need This will work with any CH340 USB-serial chip I think, but the model here is for the CH340N for USBC. A picture of the exact chip is given. I ordered one from AliExpress for about $3, and one from eBay for about $6 (because it was quicker and I was impatient). You'll also need some jumper wiring, female to female. Mine was only about 15cm, but you'll want 30cm if you want the port at the front of the printer (I'm happy with mine being further back). To attach the mount to the front-left extrusion, you'll need two M5x12mm bolts, and two T nuts (I think the printer has spares, if not you can use the ones from the spool holder, if you're not using that). # Soldering to the mainboard There's a youtube video out there that shows some points to solder RX and TX wiring on the mainboard. One of the comments points out that you can just solder to the RX and TX pins of the CH340 chip that's already on the mainboard, which is what I went with. I have a 4.2.2 mainboard - I would guess that the 4.2.7 would be just about the same. Look up the ch340 pinout. That'll show you that pins 2 and 3 are TX and RX. You can get ground from a jumper pin right near the mainboard's ch340 chip (which is right behind the microUSB port). You'll want to cut your jumper wires so there's enough space for that ground pin to make it to the jumper. There's a picture of my finished soldering job attached. I'm not experienced with soldering very small things. The approach I took was to pre-tin the wires, with a small blob of solder left on the end of each wire. I very carefully applied flux to the pin I wanted to solder to (with a toothpick), made contact between the wire and the pin, and gently pressed with the tip of my soldering iron. It took a few tries. I was careful not to contact the hot iron with anything on the board for too long - I didn't want to burn anything out. I was prepared to destroy the existing usb port (or the whole mainboard) trying to get this to work, but nothing was broken. The soldering connections are probably pretty fragile, so I taped down the wiring over the microSD port to keep it from moving. There are some cables (I think for the Z stop) that already head out of the mainboard enclosure, so I just fed the jumper cables through this same outlet. # Testing You probably want to test all of the electronics before doing any printing. I got this all working before I even started designing the mounts. For me, I think I needed to restart my raspberry pi once (I might have tried to connect it with RX and TX the wrong way around). But there's no weird setup - if it works, it'll work just as if you had plugged into the front of the printer. A bright blue LED should light up on the chip when you plug a usb cable from a rPi or PC into it. You can try this even before doing any soldering - it'll still light up. I had some cables that had the power pins "disabled" (just with tape). These didn't seem to work for me - I think the ch340 chip needs power, and I didn't solder a power cable from the mainboard to the chip (but you probably could if you wanted to). If it didn't work, there won't be much I'll be able to do to help you troubleshoot. It just worked for me, and if it hadn't worked, I don't know what I would have tried, apart from checking the solder connections with a multimeter and double checking that everything was plugged into the right pins. I use translucent filament for my printer mods, and the light on the USB port shines through this filament. It's bright enough to be a bit annoying - I might paint over that LED with nail polish. # Printing and mounting Print `Mount.stl` and `Filler.stl` - `Mount.stl` needs supports. You might want to attach the jumper cables first, just so you can get the right pins. Obviously the RX, TX, and Ground from the mainboard connect to RX, TX, and GND on the chip. The CH340 chip fits into `Mount.stl`, kind of upside-down (it should be obvious) and `Filler.stl` is a pretty tight fit into there. This will be bolted down, so it's fine if `Filler.stl` feels like it might fall out. Then you just use the M5 bolts and T nuts to bolt the whole thing to your printer, wherever you like really. I'm happy with mine being a bit back from the front of the printer, as I feel like I'm less likely to yank the cable this way. I have no idea if anybody else will attempt this mod from my instructions - if you do, please let me know how it goes :) Good luck!

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