Apple //c Keyboard HELP!

[pc154864]

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".

 

[Anonymous Freak]

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.

 

[pc154864]

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?

 

[tdiaz]

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.

 

[MacTech68]

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?

 

[tdiaz]

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.