[sebhc] H89 Power-up problems.

Lee Hart leeahart at earthlink.net
Fri Jul 7 21:55:10 CDT 2006

Mark Garlanger wrote:
> Today, the keyboard is working (although not as good as on my other
> H89). Several of the keys seem to have problems with repeated
> characters (as if the debouncing circuitry is not working well).
> Several of the keys will intermittently generate 2 (or more)
> characters when I press it (more likely if I press it slowly).
> Also, the '4' key will intermittently not register on the key
> press, but will on the key release ( and sometimes on both).
> It doesn't seem like all the keys have the problem (not even all
> the keys in a given row).

These are the symptoms of a static-damaged keyboard encoder chip. There
might be other causes (bad voltage regulator that powers the keyboard
encoder, or loose or intermittent wiring somewhere), but my money is on
the keyboard encoder IC.

> Is there any trick to popping off the keys? Maybe they need cleaning
> underneath.

No, they just pull straight up to come off. There are multiple redundant
gold plated contacts per key, so it is pretty unlikely they are the
problem unless the keyboard has suffered some grevious abuse
(submersion, etc.)
Ring the bells that still can ring
Forget the perfect offering
There is a crack in everything
That's how the light gets in    --    Leonard Cohen
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart_at_earthlink.net
Delivered by the SEBHC Mailing List

More information about the Sebhc mailing list