Creality 4.2.2 Board possible Fire Hazard!

Creality 4.2.2 mainboard showing the RCT6 chip

A few nights ago I was attempting to update one of my newest Ender 3 Pros to Klipper. I bought this printer October of 2021 (10/2021) from Microcenter, and it came equipped with the newer 4.2.2 mainboard. While attempting to flash the Klipper firmware my screen locked and the upload failed. I headed back to my computer to diagnose the issue, when I returned to my printer minutes later my heated bed was smoldering! I’m talking 80C plus danger zone! I immediately disconnected the printer and let it cool down. I wasn’t sure what caused it but I had to put the project on hold. After that the lingering thought that somehow my printers heaters stayed on really haunted me. Not long after this happened I saw this! It’s an article from TH3D detailing a possible cause of the issue!

The original round of Creality 4.2.2 boards came equipped with the STM32f103 RET6 mainboard chip. RET6 is the important part and it refers to the 512Kb flash memory. It would appear some Creality 4.2.2 boards are now coming equipped with an STM32f103 RCT6 mainboard chip! This RCT6 chip is only 256K! This can cause severe issues when trying to upload firmware. The firmware configurations we see out in the wild right now, or version you can compile yourself, are all for the 512K chip. In the article I linked above, TH3D talks about issues Big Tree Tech(BTT) ran into while trying to flash 512K firmware onto a 256K chip, the firmware would freeze and the heaters would remain on! That’s when the issue I had with my Ender 3 came into focus, it was the exact scenario I ran into! At this point I would be very wary of flashing any firmware to a newer Ender 3 Pro without first removing the mainboard cover and verifying what chip you have. At worst it costs you a few minutes and at best you avoid a possible fire hazard!

If I had gone to bed or went out to the store in between attempts at flashing Klipper onto my Ender 3 it’s likely my machine would have had a catastrophic failure, possibly cause a fire!! Please be safe and be extra careful when flashing firmware onto these machines. While there is no evidence of this issue showing up on the Creality 4.2.7 board, I would recommend proceeding with the same caution when uploading firmware.