Cardreader HP67, 4 Switches 3 Contacts?

[TorstenHamburg]

Many thanks for the hardly wellcome!
This is my first thread in this forum.

I am working on my 1997 HP76 Cardreader.
According to the 4 contact fingers aktuated by the nylon-balls i only find 3 signals on the card reader control-IC:
1. Card at reader head (HDS)
2. Card reader motor switch (MTRS)
3. Card reader write protect switch (CPS)

What is the 4. contact used for?

Regards from Hamburg/Germany

Torsten

[teenix]

It is not used

cheers

Tony