There are a total of six solderjumpers on the board:
# switching to the barrel jack as voltage supply
*JP3* and *JP4* set the source for the supply voltage.
*JP4* connects the voltage input to the barrel jack, *JP4* connects it to the USB +5V rail.
Per Default JP4 is closed and JP3 is open, making the default way of supplying voltage the USB jack.
If the Barrel Jack should be used, then **JP4 has to be opened first** by cutting the trace which shorts it by default, otherwise **the USB voltage will be shorted with the barrel jack, causing potential damage to the USB port**.
Afterwards, *JP3* can be closed with a small blob of solder.
For assembly of the board, check the [documentation folder](../doc). It contains the (interactive bill of materials)[../doc/interactive_placement.html],