How can I use external J-Link on pca10028??

[J.Kwon]

These pins do not work when I connect to nRF51822 module directly..

Like this. I cennceted VDD, SWDIO, SWDCLK and GND to nRF51822 module.

And there are not jumpers to discennect nRF51422 on board..

[endnode]

Hi, have you searched the forum? i believe there must be dozen of Q&As on the same topic (how to flash nRF5x on custom board with nRF5 DK's ports P20 or P19), this is just one example (follow the links in bottom section, there is even explanation why you don't need to "cut" internal nRF5 chip on the DK board when you want to flash the external).

[endnode]

Also all GPIO settings (buttons, LEDs, SPI, TWI, UART...) should be checked if used by the example, it will most probably differ.