I have found that in AGND_E & AREF_EN jumpers of STM32-E407 board, even though there are exposed pads for shorting, these pads are internally short in the PCB. Kindly clarify how to open circuit this jumper. Should I physically cut the track over which conformal coating is already applied? It doesn't make any sense. Is there any problem with my understanding of these SMD jumpers ?
Yes, exactly you cut with thin and sharp tool between the pads. Then to be extra sure use multimeter tool and measure in short circuit detection mode between the pads - if cut was good there should be no beep sound.
If you wish to re-stablish the connections just solder the pads together.
We use such SMT jumpers that allow slight hardware modifications but are not likely to be used repeatedly or often.
Thanks for the prompt reply LubOlimex. I guess we can close this topic.