There are two keyswitches under each key, each having three contacts.
Between Contact 1 and Contact 2 on the circuit board, there's an electrical gap. [see photo]
A struck key pushes down a 3rd contact inside a dome in the rubber strip.
This, contact closes the
gap and turns on the switch.
A second keyswitch under the same key turns on slightly later than the first.
The delay is proportional
to how hard the key is struck and it determines the
note's velocity value.
Sometimes a button contact will tear away from the rubber strip so make
sure none of them are torn.
Damaged strips should be replaced with
NEW KEY CONTACT STRIPS, available in our Parts Shop.