24 Aug
2015
24 Aug
'15
6:27 p.m.
On 08/23/2015 03:28 AM, drlegendre . wrote:
Howdy gents,
Working away on the recently acquired Osborne 1. Seems there's something
wrong with the KB - and if I didn't know better, I'd say it's a case of
shorted contacts.
The KB connector is 24 pins, double row header like a short floppy or IDE
header.
On the KB side, there are two "shorted" groups of pins. Group one is 2X
shortred pins, group two is 5X shorted pins.
I just prodded mine with a meter, and the only continuity I get is between
pins 2 and 23 (numbered as follows, looking into the keyboard connector,
with the cable exiting toward the right)
_____________________________________
| nc 02 03 04 05 06 07 08 09 10 nc nc |
| nc 14 15 16 17 18 19 20 21 22 23 nc |======
-------------------------------------
Thing is, this KB is not really built to be serviced,
best as I can tell.
Yeah, I just opened the case on mine, and it's a pretty nasty design -
cheap as possible :-( Wish I'd tried that keyboard on my system now so you
knew it had problems!
With such limited access, I don't see many avenues
other than flushing with
solvent(s) and hoping for the best.
Yeah, I'd do that first - or maybe soapy water followed by a flush with
distilled, then leave it for a week or so to dry. Can't hurt.
If that doesn't work... break the melted plastic bits off, take the thing
apart, clean the membrane. Reassemble and put blobs of glue where the
melted plastic bits were. If you have a drill press, counter-sink the holes
on the underside of the metal plate first; it'll give the glue more plastic
to adhere to.
If gluing doesn't work out... urgh. The switch bodies do seem to have a
little lip around the edges where they rest up against the membrane, so it
would be possible to slot metal bars down between the rows (secured at
either end somehow to the metal 'baseplate' below) in order to keep the
switches from falling out - but it would certainly be a bit of a project!
Nasty keyboard, though! I expect mine will go the same way at some point :/
cheers
Jules