Originally posted by protocold
Actually how does the A switch work? I am guessing that when the aperture ring turn into "A", a small tiny screw on the ring itself would push the copper on the "A" switch onto the contact below? I am kinda confused.
when you rotate the aperture ring to the A position, the springy contact shown i the photo touches a contact to connect the A pin to the lens mount base.
If you get desperate, you can make this connection perminant, because all the A pin does electrically is connect the A pin to the lens mount