Apple //c Keyboard HELP!

Discussion in 'Apple Collectors' started by pc154864, Dec 12, 2013.

  1. pc154864 macrumors newbie

    Joined:
    Dec 12, 2013
    Location:
    Milwaukee, WI
    #1
    So I've always love writing programs in Integer BASIC. I would use an emulator on my modern Mac but recently I got the urged to finally "upgrade" to the real-deal.

    I bought an Apple //c on ebay as my "first" computer. Everything seemed to work

    flawlessly except for a few keys.

    When I press certain keys (on the keyboard) it shows something else.

    For example:

    The 'dash/under-score' key (when pressed) says:
    ]' 90L/-

    The 'plus/equals' key (when pressed) says:
    =P
    UK,
    The 'back slash' key (when pressed) says:
    M5TJM\`

    I also noticed these (key outputs) change too..


    Does anyone have slightest idea on why this is happening?

    Is there a way to fix this?

    Please dumb all this down for me, thank you for your "output".
     
  2. Anonymous Freak macrumors 601

    Anonymous Freak

    Joined:
    Dec 12, 2002
    Location:
    Cascadia
    #2
    If the outputs change, then it's likely a dirty keyboard that is triggering multiple key presses for each actual physical press. You'll want to disassemble and clean it. Also look for corrosion on the keyboard PCB, shorts or breaks could also be at fault.
     
  3. pc154864 thread starter macrumors newbie

    Joined:
    Dec 12, 2013
    Location:
    Milwaukee, WI
    #3
    Alright, so I'll just remove all the keys and then what? Should I solder off the key pressing mechanisms themselves? Or is there a easier way to clean it?
     
  4. tdiaz macrumors 6502

    Joined:
    Feb 7, 2006
    #4
    What you're describing sounds more like the AY3600PRO, the keyboard encoder IC.

    The matrix is setup as such:

    9OL/-]' RIGHT-ARROW
    8J;,0[ SPACE LEFT-ARROW
    7UK.=P UP-ARROW DOWN-ARROW
    5TJM\` RETURN DELETE
    6YGN
    4RFB
    3EHV
    2WSC
    1QDX
    ESC TAB AZ

    The AY3600 will only take one key at a time, if you hold one down, when it starts to auto-repeat, if you press another and let it go, while still holding down the first one, the repeating key will become the second one, even if the first one is still the one held down.

    If it's outputting multiple characters it's as if the everything in that column is being pressed in sequence.
     
  5. MacTech68, Dec 16, 2013
    Last edited: Dec 16, 2013

    MacTech68 macrumors 68000

    MacTech68

    Joined:
    Mar 16, 2008
    Location:
    Australia, Perth
    #5
    Is it just me, or isn't there some history on the encoder IC being overly sensitive to static discharge, producing this exact behavior ?

    Unless you see corrosion or evidence of a liquid spill, I'm wondering if it could be bad power or dirty clock?
     
  6. tdiaz macrumors 6502

    Joined:
    Feb 7, 2006
    #6
    The //c overall is pretty forgiving with power input, though it will try to work.

    I'm leaning on the encoder myself, as for cleaning contacts? There's no real point. It's obvious they're working. It's not possible for one switch by itself to do that. There's something going on that should be blatantly visible, if it's keyboard related, or not, if it's encoder related.

    As for corrosion, that it would zero in on only the encoder chip, and the rest be working? Not terribly likely. Though I suppose, not impossible.
     

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