12 Sep
2006
12 Sep
'06
4:55 p.m.
On Tue, 12 Sep 2006, Tony Duell wrote:
I found out last night that the switches are the same. The question then
would become "are the switches on the junked keyboard still good?". See
http://home.online.no/~kr-lund/repair.htm
So, I'm
fooling around with my Tandy PT-210 printing terminal again.
Upon disassembly, these switches are revealed to have rubber domes inside
that electrically connect two isolated semicircles by pressing a circle of
These sound very similar to the switches used on the TRS-80 Model 3 and
Model 4 keyboards. They may even be the same parts -- the ones in the M3
and M4 were made by Alps IIRC. Any maker's name on these? If they are the
saem, a junk M3 or M4 keyboard would be a source of spares. A couple more suggestions. Chemtronics sell (sold?) a
rubber keyboard
repair kit. It was a 2-pack thing that you mixed and then put a bit on
the conductive rubber pad. The problem was that it's expensive, and once
mixed you have to use the whole lot (enough for about 100 switches I
think).
You can't mix up small batches? 100 is about how many switches I
have to fix (two terminals worth)
When I did my M4, I had a few dodgy swtiches. I found
rubbing the
conductive rubber pad with a soft (6B, if that means anything across the
Pond) pencil helped a lot.
This makes sense as conductive rubber is graphite-impregnated to begin
with. I think that repair kit mentioned above might be powdered graphite
with some sort of binder.
And then I put said switches in little-used places,
like the number pad.
I don't know if that's applicable to your terminal, though.
See http://userwww.sfsu.edu/~hl/c.TR210.terminal.html for pictures of one.
No number pad.
--
David Griffith
dgriffi at cs.csubak.edu
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