Registered: 06/13/10
Posts: 440
Loc: Harrisville Pa USA
FSX is also semi-weighted as is 4x,Ketron G-70 Etc. Same keybed Yamaha uses in High end Synths,workstations etc...Hope this helps. But semi-weighted is not for every ones liking as Don Mason talks about....Harold
Registered: 03/02/02
Posts: 1221
Loc: Preston, Lancashire, England
My guess is that the FSB is an improved PSR rather than a cut down FSX. But the name implies the latter and the description has a lot of features in common with the FSX.
Having disassembled both FSX and PSR Keybeds the main difference is a discrete metal spring and some weight on each key for the FSX . The aftertouch mechanism does not affect the keybed feel. The FSB has gained some weights and that could mean a spring is necessary because the very crafty but inexpensive use of the rubber contact strip as the spring mechanism on the PSR might not be strong enough.
Anyone seen a service manual? That would give some good clues!