Re: Problem with Apple IIc...for anyone who wants to help...

[labelas@hotmail.com (Labelas Enoreth)]

In article <3781ED14.B21DD6A6@swbell.net>, rubywand@swbell.net wrote:

> Labelas Enoreth writes ...
> > 
> > Well, when I looked at all the ICs below the keyboard and that seemed to
> > connect to it, all I remember seeing offhand were the MMU, CPU, and a few
> > other things which didn't seem to be directly related to the keyboard,
> > except for the one chip I didn't recognize that was soldered on.
> > I don't see any problems on the board itself, which was what made me think
> > that the keyboard module was bad, but as I said, the other fine working
> > one exhibited the same problem.
> 
>      Our IIc+ exhibits a similar problem but not so extreme-- it will
sometimes
> double or triple a keypress. I've been waiting to get a schematic before
trying
> a fix.
One thing I've noticed between the earlier and later IIc is that in the 2
I have, the keys depress with a much more noticeable feeling than the
later model I have, so much that I wondered if something had gotten
spilled into them, but I have noticed it in more than one...I wonder if
they cheaped out on the keyboard and later regretted it or something...


> 
>      The basic problem appears to be poor key debouncing by the KB input
> circuit. This may relate to a defective component in a Resistor-Capacitor
> timing circuit used for deciding how long to wait for contact bounce to
> subside. (Unless the debounce timing is entirely digital, in which case a fix
> could involve a circuit change.)
> 
>      Something I have not checked is the possibility of a bad power supply
> output. Keyboard encoder and similar IC's sometimes use -5V or -12V. If one of
> these were missing or off, the computer might work fairly well but screw up
> when an IC counting on a negative voltage is involved. You might check your
> voltages.
Hmm. Where might I look for the part<s>, and to replace it?

  
> 
> 
> > I guess I'll investigate slightly deeper
> > when I get some extra time. Heh. I got it for $5 at...somewhere...I think
> > it was a thrift store. I dunno, I just have this faint notion that I
> > should try to find each of the IIc rom revisions for some reason...
> 
>      Sounds like a worthy quest! 
Heh, thanks...I'm known for deciding to depart onto random quests like
this, but I don't really style myself a collector...I actually tend to
dislike a lot of the people who swoop in and get all the cool stuff before
I do, solely because they've heard that 'apples are good computers to buy
cheap at thrift stores' amd I don't know how many times someone gestures
at an old Apple II or mac and says 'ohhhh, well that's an _Apple_ you
know, so I wouldn't want less than (5-10x the amount I'd ever pay for
it)...like $100-something for a IIe with 'tons of games' (about 20). I
guess...I guess I'm a collector, but my heart's in it rather than my
wallet and my large, spacious collector's vault (I actually have shelves
spilling various computer equipment all over my room, it looks like some
sort of...warehouse or something...)

I've run into some funny stuff though, like a IIc with the v255 rom, and
yet the drives with it were all UniDisk...odd. (I mean, why have a UD 3.5
if you can't use it? My only guess is that somewhere along the way a big
bundle of stuff got broken up and distributed unevenly)

> 
> > All
> > I've ever found were the 255 and 3 for some reason. Plus, this one came
> > with some good (IMO) accessories, like the thermal printer, the apple
> > paddles and joystick, the RF modulator...so I guess the rest was worth
> > it...
> 
>      Just the RF modulator is pretty nice. It fits like a glove and does
a good
> job of converting the output for color TV.
Yeah, it's a nifty piece of equipment...Still searching high and low for
all the Apple II 'extras' that I don't have yet...like the beige&orange
joystick, or the platinum paddles...or the modulator for the IIe.