There are none, all soldering to the psio switch board are made on the back of the mobo, while all soldering to the mobo for the ps1d are on the front.
I think it is a decoupling cap which has its double on the flex cable. So it is removed from the mobo and put on the flex cable ... if im right. On the Pu18 board there is only 1 cap to be removed, on the Pu20 i think 4 or more, therefore plural.
A new feature "per game" settings appeared in the new firmware. Which settings are meant by this? I cannot find anything on the new firmware in the internet. And the site with further information "psx.i74.de/osdsettings" does not exist or is not reachable by any of my browsers. Does the game.db...