I have a keytronic keyboard which is the only din connector keyboard i happen to have and I'm attempting to get it working again. while most of the keys work , about 10% do not work.

I have checked continuity and the membrane seems ok , the connection between the membrane and chip also seems to be ok as well.

the only continuity error i think i found was in the actual cable. there is a yellow wire that comes out of the cable into the circuit board for the keyboard. this wire seems to have no connection at all to the din connector. the yellow wire does seem to be used on the actual circuit board and doesn't simply end at the connector.

So i'm wondering , what does the yellow wire on a keyboard din cable do?

I'm surprised that if it is needed... that the keyboard is able to function as much as it is without it.

or could my problem be something else