According to the schematic on the Waveshare site, their board doesn't power the Pico at all - the choice on the jumper is where the servos get their 5V power from (the Pico's VSYS or the external PSU), with the Pico itself always being powered from the USB/VSYS.
So either your board is a different version, or there's something broken about it.
I would start by unplugging the Pico (but leave the servos as they are, they could be part of the problem) and measure the voltage (relative to GND) on all the Pico pins. One possibility is that it's being back-powered through one of the I/O pins; this is less likely than some other devices, but not impossible.
If the board is as per schematic, it should not matter if you plug the USB in at the same time as the external power.
So either your board is a different version, or there's something broken about it.
I would start by unplugging the Pico (but leave the servos as they are, they could be part of the problem) and measure the voltage (relative to GND) on all the Pico pins. One possibility is that it's being back-powered through one of the I/O pins; this is less likely than some other devices, but not impossible.
If the board is as per schematic, it should not matter if you plug the USB in at the same time as the external power.
Statistics: Posted by arg001 — Mon Oct 14, 2024 1:28 pm