23 Aug
2015
23 Aug
'15
12:02 p.m.
On 23/08/2015 09:28, 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.
Thing is, this KB is not really built to be serviced, best as I can tell.
The switch matrix is made of two layered flexible circuits, and the key
assys are 'riveted' in place, by melting over the plastic pins. So I see no
way to disassemble it and give it a clean.. and then, even so.
With such limited access, I don't see many avenues other than flushing with
solvent(s) and hoping for the best.
What's to be done? Is this one.. done already?
I had a similar issue on a
Osborne a couple of weeks ago. I ended up
using a sharp knife to cut the melted pins on the rear of the keyboard
to remove the switches. Lifted the membrane and cleaned it before
refitting. To re-attach the switches, I used some super glue on the back
were each pin is and used a hot glue gun on the front in between each
switch.
Whole process took about an hour but has been working fine since. I
think this is caused by the cable constantly pressing down on the keys
when the keyboard is clipped to the front of the machine.
On an Osborne I repaired last year, just removing the the keyboard
assembly and giving a bit of a flex was enought to release the stuck key.
Cheers,
Dave