Bitmain Antminer S19 S19J S19J Pro combined control board BeagleBone board 
 
The control board is composed of two circuit boards, an IO board and BB board, and is compatible with most Antminer S19 , S19j and S19j Pro models. This board has an SD card slot on the back, if your S19j miner doesn't have any SD card or micro USB slots on the front, you should use this combo board. When using the TF card to swipe, you need to open the top cover to see the SD card slot. The control board can be used to replace and repair faulty control boards for Antminer S19 , S19j and S19j Pro that are not working. This control board is also used for installing custom firmware .