Groups | Search | Server Info | Login | Register

Groups > comp.sys.apple2 > #737

Keyboard issues ...HELP!!!!!

Show all headers | View raw

I recently got a Apple II+ keyboard from John Woodall. He couldn't
test it so it came with no guarantee. Well the keyboard arrived, and
the first thing I noticed was the traces on the back of the keyboard
were damaged, and it was obviously this keyboard would need some
jumper wires to get at least 4 keys working. So instead of complain to
John I decided to just jumper the broken traces with fine wire.

Before plugging in the keyboard to test it I decided to look at the
daughterboard just incase. The decoder chip was a NKBD-931 (8018 UX),
and one of the pins was obviously out of the socket. I bent it back
and put it back in the socket correctly. Plugged it all together and
fired up the machine. Most of the keys worked, but some didn't. I
shorted the back PCB on of the keys that didn't work to see if the
issue was the key mechanism or something else. Shorting the key pins
seemed to work and displayed the appropriate character on the screen,
so I figured the issue was with the key mechanism. I was able to get
some of the keys working by spraying some contact cleaner down the
shafts. Thats when things went terribly wrong. I don't know what
happened, but suddenly I started geting multiple characters on the
screen from one key press, some keys seemed to suddenly stop working,
and others when pressed produced anything from 2 character to a stream
of 20+ characters in repeating patterns on the screen. Crazy!

Well, thats where I'm at now. I've looked at the board and can't see
anything obviously bad, so I'm stumped.
I was also wondering if the pin on the decoder chip was out for a
reason. I can't see any reference to the NKBD-931 on the net.

I do have a spare MM5740 decoder chip from an original Apple II
keyboard (raised power lamp), but I'm very wary to try it as I'm not
sure if that chip works in the II+ keyboard, and I certainly don't
want to fry it.

Can anyone help?

Thanks in advance.

Phil

Back to comp.sys.apple2 | Previous | Next — Next in thread | Find similar

Thread

Keyboard issues ...HELP!!!!! Nama <forums6000@mac.com> - 2011-04-05 22:11 -0700
  Re: Keyboard issues ...HELP!!!!! Nama <forums6000@mac.com> - 2011-04-06 03:42 -0700
    Re: Keyboard issues ...HELP!!!!! mwillegal <mike@willegal.net> - 2011-04-06 05:31 -0700
      Re: Keyboard issues ...HELP!!!!! Nama <forums6000@mac.com> - 2011-04-07 01:27 -0700
        brainboard update - was (Re: Keyboard issues ...HELP!!!!!) mwillegal <mike@willegal.net> - 2011-04-07 05:18 -0700

csiph-web