Re: Apple II+ Keyboard repair

[Michael J. Mahon <mjmahon@aol.com>]

kynrek <kynrek@gmail.com> wrote:
> On Oct 17, 5:41 pm, rittwage <rittw...@gmail.com> wrote:
>> On Oct 17, 1:51 pm, kynrek <kyn...@gmail.com> wrote:
>> 
>>> Someone gave me and apple ii+ but the keyboard did not work at all,
>>> only the reset key worked. I replaced the keyboard encoder ic and a
>>> few other components on the encoder board and now some of the keys do
>>> make characters show on the screen :)
>> 
>>> However the keys are not showing the right characters. for instance
>>> the letters s and d both output the letter w, most of the number keys
>>> output a ?. I think the individiual key switches might be bad but I'm
>>> not sure. I can remove the key caps but I don't know how to get to the
>>> switches underneath, I dont see any screws on the metal plate that
>>> seperates the top of the keybaord with the  key caps and the underside
>>> with the switches underneath.
>> 
>> Where did you find an encoder chip to replace yours?!
>> 
>> -Pete
> 
> I got my encoder from this here
> http://www.ebay.com/itm/AY5-3600-GI-Vintage-LSI-IC-40-Pin-1978-AY53600-/390121009363
> on eBay he is asking 19.99 but I offered 12.95 and he accepted. This
> chip brought the keyboard back from the dead. Replacing the other
> components was not necessary to get it to start responding but I did
> it just to preserve the encoder circuit. :)

Heck of a time to point this out, but your old encoder may actually be OK. 

The encoder has very high-impedance inputs, so board contamination can
prevent it from working. I wouldn't throw it out until it's been cleaned
and found not to work on a clean keyboard. 

That, BTW, is why even relatively clean moisture can render a keyboard
inoperative. 

-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon