FYSETC Spider V3 — simultaneous loss of 5V and CANBUS

[Ak_PuLk0]

Hi everyone,
I recently ran into a serious issue with my FYSETC Spider V3 (STM32F446) while running my Voron 2.4, and I’d like to share the details to see if anyone else has experienced something similar. I’m trying to understand the root cause before I set up my replacement board, so I don’t end up frying another one.


Setup / Context

• Voron 2.4
• FYSETC Spider V3
• UART connection used to power the Raspberry Pi 4 from the Spider
• CANBUS communication with an EBB toolhead board and a Cartographer
• Raspberry Pi powered via UART from the Spider, but I also had to connect a USB cable between the Pi and the Spider to get communication working
• DC5V jumper enabled → no external 5 V supply for the Pi

What happened

• Everything was working fine at first
• A few hours before the failure, I installed KlipperScreen and ran TMC Autotune (not sure if it’s related)
• Klipper displayed a 5 V undervoltage warning, suggesting to lower the frequency
• Shortly after, the Pi stopped powering via UART
• Measured on UART output: only 4.2 V open-circuit between 5 V and GND, ~17 Ω resistance
• Lost all CANBUS communication with both the Cartographer and the EBB2040
• After the failure, some TMC2209 drivers started heating up significantly, even without load
• I suspect the NXP A1050 CAN transceiver may have failed (I applied IPA across the board because I couldn’t see any visible burn marks, and only the NXP 1050 chip caused the IPA to evaporate almost instantly)
• It could also be an issue with the 5 V regulator

My questions

• Could powering the Raspberry Pi via UART while also keeping the USB cable connected cause this type of failure?
• Is this a known issue with Spider V3 boards?
• Has anyone else ever lost both CANBUS and 5 V at the same time like this?
  

Planned solution

• Replace the Spider board
• Power the Raspberry Pi 4 using a dedicated MeanWell RS25-5 (5 V) PSU
• Keep only the USB cable between the Pi and the Spider (no more UART power)
• My assumption is that powering through UART may have caused the problem, but I’m not 100% sure

Any feedback, advice, or similar experiences would be greatly appreciated — I’d really like to avoid frying the new board the same way.


Thanks in advance!