Apple II + keyboard repair...help needed

[Vipersan]

So ...I have aquired probably the nastiest Apple II + keyboard ...
TBH I was lucky to get this..as Apple II + europlus keyboards are rare especially in the UK.
It doesn't use individual key switches ...but instead many sprung metal contacts which are activated by pushing down the keys towards a PCB.
It does however have the 25 pin in line female connector ...which I an hoping to marry up with the working keboard interface I already have (25 pin male connector on this board)
First however It will take much fixing as the plastics are brittle where the screws mount the keyboard pcb ...so will need a fair bit of glueing and re-enforcing.
This process I have already started ..
Slowly I am getting there.
..and whilst I wait for each stage of 'curing' of the epoxy...I figured it would be a worthwhile task to note the connections to the 25 pin plug from the keyboard PCB for testing once reassembled.
I Dont want to handle the keyboard in between fixes...so used a very poorly scanned schematic to make a list of just which key when pressed bridged which pins on the 25 way connector.
This I can used when the keyboard is reassembled with a meter in continuity mode to test.
This is my list so far ...but obviously incomplete as I dont have the non qwerty keys listed.
Shift CTRL Reset etc ..so no idea which pins on the 25 way connector are used for which function.
I'm guessing these non qwerty special keys must use pins 19 through 25 ..but no idea of how ...an cannot find any data on this...
Can anyone help ?
here is what I have so far..
1 - (7 -2)
2 - (6 -2)
3 - (17 - 5)
4 - (17 - 6)
5 - (17 - 7)
6 - (17 -8)
7 - (17 - 9)
8 - (17 - 10)
9 - (17 - 12)
0 - (17 -15)
A - (9 - 2)
B - (11-9)
C - (11-7)
D - (13 - 5)
E - (14 - 7)
F - (13 - 6)
G - (13 - 7)
H - (13 - 8)
I - (15 -14)
J - (13 -9)
K - (13 - 10)
L - (13 - 12)
M - (12 - 11)
N - (11 -10)
O - (16 -14)
P - (18 - 14)
Q - (14 - 5)
R - (14 - 8)
S - (5 -2)
T - (14 - 9)
U - (14 - 12)
V - (11 - 8)
W - (14 - 6)
X - (11 - 6)
Y - (14 - 10)
Z - (11 - 5)
* : - (17 - 16)
= - - (18 - 17)
RESET - (
ESC - (8 -2)
REPT - (
RETURN (18 - 2)
CTRL - (
+ ; - (15 - 13)
LEFT - (
RIGHT - (
LSHIFT - (
< , - (15 - 11)
> . - (16 - 11)
? / - (18 - 11)
RSHIFT - (
SPACE - (10 - 2)

 

[Vipersan]

Here are a couple of photos showing the keyboard...
I have used 2mm allthread with nuts to replace many of the screws with stripped out threads in the plastic frame..
plus re-enforced many parts of the frame with a combination of JB weld ..or Q-Bond with glue/crystal mix.

 

[stanleyruppert]

 

[Vipersan]

Many thanks Stanley ..That schematic will be very helpful ....and much easier on my old eyes.
rgds
VS

 

[stanleyruppert]

Hope your keyboard repair is successful. I have one of those sprung metal switch versions and it is finicky. Here is an additional reference for troubleshooting the encoder/MB that I’ve found helpful. Contributed by user speedyG on an Apple forum. I may have an extra Apple A keycap if you need one. Need to confirm style match to your photo.

 

[Vipersan]

working through the keyboad now to see what works and what doesn't
either mechanical issues or restrictions/ masking of the keyboard contacts ...so later the pcb will come off again to investigate.
All Alphabet keys except S an U working just fine.
None of the numeric keys are functioning plus 0 > 9
RESET ESC RETURN CTRL LEFT and RIGHT arrow
also ?/ not working
One of the shift keys responds (left) whereas the right will not press down (mechanical issue)
It is possible that carless placing of the kapton tape holding the plastic seperator sheet is restricting some key contacts,
But it should be possible from the results gathered so far ..to pin down these problems.

Also ...again ..thanks Stanley..
IHopefully I can solve this mystery..
I have the A key cap ...just not fitted atm
Not quite ready to throw in the towel just yet.
Cheers buddy

 

[Vipersan]

for most of the numeric keys 3 > 0 the common denominator is pin 17 on the 25 pin connector ...and was making poor pcb contact of the metal strips.
similarly numeric keys 1 and 2 had pin 2 on the 25 pin connector...again tweaking the contact points on the metal strips sorted this
and also affected the return key and the S key and the ESC key (pin 2 of the 25 way connector)
The U key was just dirty contacts
Reset pins 21 and 22 local contact issues
CTRL key localised contact issues ...more cleaning and tweaking
the ? key again localised contact issues
The Right shift key plunger was hampered by a small amount of glue in the plunger guide which had run in there (my fault)
..and I suspect similar with the return key which I'll attend to tomorrow ..
daylight being helpful with that.
Which leaves the Left Arrow and Right Arrow keys neither of which work atm...
I'm suspecting the metal strips connected to pin 14 of the 25 way...as this again is a common factor.
More to do but Very close I think.

I'm adding a photo of this nasty keyboard inside ..just so anyone having issues understanding what I'm working with get a better idea...

 

[Vipersan]

So very very close to 100% now..
The main issue with this nasty keyboard is that it is bowed slightly laterally.
Thus it required extra bolts directly through the plastic 'frame' and pcb at the top of the keyboard..
Strategically drilled and placed such that no pcb traces were cut.
Fully cleaned and assembled but may well have to be taken apart one last time to tweak the contacts of the 1 key and the 4 key.
both are a bit hit and miss...though they do occasionally work.
All of the other keys are 100% reliable.
Taking it apart again is quite messy and so it can wait until I'm ready to face it again.
This has been a labour of love...but has been both an education ...and a pain in the rear.