Hi there,
we are trying to connect an Apple ][ Europlus keyboard to our Apple 1, following the pdf made by Wendell Sanders in 2010 ("Using Apple II Keyboard for Apple 1")...
We connected everything, we cut the right traces, made the jumpers etc...
The keyboard turn on, light's on, clear screen (REPT) works, ctrl-reset works... but keys act weird! 
Here's what we obtain:
Key I press (space) what appears on screen
1 0 (means: I press 1, I read 0 on screen)
2 2 (...etc)
3 2
4 4
5 4
6 6
7 6
8 8
9 8
0 0
: :
- ,
Q P
W V
E D
R R
T T
Y X
U T
I H
O N
P P
A @
S R
D D
F F
G F
H H
J J
K J
L L
; :
Z Z
X X
C B
V V
B B
N N
M L
, ,
. .
/ .
As you can see, some keys are correct, some are not
We changed every TTL IC on the keyboard (7400, 7404, 555) but no way. Also changed the 6520, same result. Double checked any connection almost 20 times!
We also swapped the 331-0931-B chip from a working APPLE 2 and the result is exactly the same, so we're sure this keyboard encoder is working.
Any hint? help please!
PS where can I find the 128 bytes ASCII table used in APPLE 1? I can't find it anywhere - maybe checking the scancodes in binary I can trace something (e.g. some lines connected togheter somewhere?)
Check the bit 1 connection between the Apple-1 and the keyboard. I'd guess that there's no continuity there - every error you've got is consistent with losing the low-order bit of every character, but still getting all of the others.
And this is an ASCII code chart that shows the bits clearly:
Thank you so much! That's EXACTLY what I need!
Tomorrow I will check
PS I saw that this is the normal, well known ASCII table! I feel myself a little stupid
I don't know why but I was believing that Apple 1 was using some different encoding 
I would suspect one of the 2504 shift register chips, specifically the one controlling bit0 of the display. If you move the 2504 chips to different positions does it behave the same?
Well,
with an oscilloscope I checked B1 at pin 2 of 6820: it was 0 every time a key was pressed.
So I traced the cable from keyboard (pin 12) to the A1 connector (pin 5): it was OK.
So I traced from keyboard (pin 12) to the 6820 (pin 2): OK again! (tested also without 6820)
So I went on the keyboard circuit. There I traced B1 from the kbd controller (pin 14) to the input of 7404 (pin 13):
NOTHING!
So I checked for any short between pin 13 of 7404 and other pin around... nothing again.
So I jumpered pin 13 of 7404 to pin 14 of kbd controller... et VOILA', keyboard is working!
Thank you for help