Mmm...deadly deadly honey.
When I looked at my PC-FX innards long ago, I think I concluded that it was some sort of wait-state-related-fix, but don't repeat that to anyone, my memory isn't perfect. I'd check again with mine, but it's such a pain to put the PC-FX back together when you lack magnetized screwdrivers, and even then, you have parts left over. >_>
It would be interesting to know if it's on all PC-FXs, or only ones of a certain serial number range.