Now solder the switch board wires to the key contacts:
Take care that you don’t accidentally desolder the internal wires.
Switch board 1 (20pin connector):
Wire 1 gets soldered to the common connection (bus bar).
Wire 2 gets cut.
Wires 3 – 18 get soldered to key contacts 1 – 16.
Wires 19 and 20 get cut.
Switch board 2 (16pin connector):
Wires 1 – 16 get soldered to key contacts 17 – 32.
Switch board 3 (16pin connector):
Wires 3 – 14 get soldered to key contacts 33 – 48.