[comp.sys.apple2] repeating key -- how can I fix?

gwyn@smoke.BRL.MIL (Doug Gwyn) (05/02/90)

In article <90121.013243BRL102@psuvm.psu.edu> BRL102@psuvm.psu.edu (Ben Liblit) writes:
>Recently the "i" key on my Apple //e keyboard has been a bit ... enthusiastic.
>For each press, I tend to get anywhere from two to six "i"'s instead of just
>one.  This seems to happen most often when I'm typing at a good clip, rather
>than pausing longer between keystrokes.
>Does anyone know what could be causing this?  More importantly, is this a
>repair job I can pull off myself, or will I need to send the thing out to the
>repair shop?

Sounds like contact bounce, probably aggravated by crud on the contacts.
You can clean the contacts with a 1/8" wide strip of business card once
you carefully pull off the key cap.  Hold the shank of the plunger down
with the card inserted between the contacts, then pull the card through
the contacts a couple of times.

I take no responsibility if you manage to break the keyboard trying to
pull of the key cap.

sb@pro-generic.cts.com (Stephen Brown) (05/06/90)

In-Reply-To: message from BRL102@psuvm.psu.edu

Ben Liblit asks about a cure for his over-enthusiastic "i" key.  I have had a
number of defective switches on my IIe keyboard. Right now, my "L" key is
really flaky (you can't see how many times I have to poke it to get one darn
"L" out of it!!!).  I have been able to get replacement switches from an Apple
dealer. But be forwarned that the IIe had four different keyswitches used in
their keyboards, so you'll have to have the dead one with you. An alternative
is to increase the value of the bounce mask capacitor on the keyboard decoder
chip. The capacitor (C71) is currently 0.022 uF which gives something like an
8 mS mask. You could try increasing by tacking on a 0.056 uF capacitor and
increase the mask to 25mS.  NOTE: THIS WILL VOID ANY WARRANTY.  Oh yes, new
keyswitches for my IIe cost $7 each.

Stephen Brown

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