Solution:

Actually, the connector of CPU card can be used with PS/2 mouse only after connecting with the keyboard translator. It's result from the keyboard translator receives and transfers the signal to CPU card directly and the signals will be conflict to each other if there's another signal from the keyboard. The connection is as below. CPU <--> Keyboard translator <--> front side keyboard <--> back side keyboard <--> keypad It's recommended to connect the keyboard with the front or back side connector to avoid the failure.