Update 2 on ESP32 3D printer control board

v0.9 of the 3D printer control board I am working on. Named MRR ESPA. ESPA because it is based on the ESP32, and "A" since this is the basic version of the board. If anyone has better suggestions for naming these boards (there will be an advance version of the board featuring the use of I2S, once this version is sorted out), please leave them in the comments. Otherwise, the advanced board is going to be called ESPE. 😅

When I tested it with a small 12V PSU (6A), connected with a heatblock to simulate the heat bed, it kind of worked. The E0 heating worked too.

And then I connected it to my test printer (a FLSun Cube frame modified into CoreXY mechanics), flipped on the switch, and saw a thin line of smoke rising up from the IRLR3034 MOSFET for the heat bed. Wow! Somehow, it seems the heat bed MOSFET has failed in the open mode, and was basically trying to heat up the heat bed at max power. So I disconnected the heat bed (as you can see from the picture) to carry on testing.

The hotend heated up fine. For once. One time. I set 60degC, it went to 60degC, and maintained it. Then I tried to set 120degC. Nothing happened. The LED indicating power going to the hotend went off. Nothing. Rebooted, nope. Powered down and up, still couldn't get the hotend to heat. But the fan, which uses the exact same setup as the hotend, continued to work. No issues.

I went through the schematic and PCB layout, and it doesn't seem to be an issue with these. My gut feel is an issue with the bed MOSFET and the voltage shifter for the hotend. The MOSFET was reused from a previous version of the board, and could have been faulty in the first place (which, thinking back to when I connected a hotend to it, seems to be so). The issue with the voltage shifter could be bad soldering. I guess I should get better quality solder paste, instead of dried up one which I tried to revive using flux.

Next step: solder a new board based on the current schematic, using new parts. If the problems persist, then it is an issue with the design and I will need to rethink everything. If not, and it works, then hurray! On to the next stage of testing.

Note: Issue fixed. Pre-launch version now available here. Some information on this has been updated here.