[GreenKeys] model 28

[Jack]

Byron,

The terminal strip along the back of the machine is called the "C Strip".
You should find the keyboard contacts on C9 and C10. If you have jumpers on
those screws, then there's good chance the keyboard is already wired up.
Make sure you hit the "KEYBOARD UNLK" red key on the keyboard (if you have
one). If the "KEYBOARD LOCK" red key is depressed, it locks out the keyboard
contacts (usually). If nothing else seems to work, take an ohm meter to the
9 and 10 connections and look for a short. If you type on the keyboard you
would see the characters being sent (opens and closes the 9 and 10 short).
Also check to see if the BREAK key is working. If it is wired in series with
the keyboard, it should open the loop. Sometimes the BREAK key is not wired
in, so don't used that as a definite example.
If the electrical troubleshooting desn't tell you anything, then you have to
check the mechanical part of the keyboard. The small metal box that normally
is labeled "DO NOT OIL" is the "signal generator" for the keyboard. It sits
just left of center on the keyboard, just behind the top row of keys. It has
a toggle lever that operates the internal contacts. There should be a small
spring associated with that lever. The spring is about 3/8-inch long. If it
is missing, the keyboard might not work at all. Watch to see if that lever
operates when you type on the keyboard. You could also open the "can" to see
if the internal contacts are operating. There is a small "T" shaped moving
contact that generates the marks and spaces for the electrical circuits of
the keyboard. It is the "heart" of the keyboard. Check that out to make sure
it is following the keyboard's mechanical operation. You could use your ohm
meter to trace the conatcts back to the C strip, also.
Good luck...

Jack WA2HWJ