24 Jan
2002
24 Jan
'02
7:35 a.m.
On Jan 24, 15:50, CLeyson(a)aol.com wrote:
Just got myself an old BBC for 6502 assembler. My
problem is that
some of the key contacts need cleaning. My question is -
Am I correct in thinking that all the keys need to unsoldered from the
PCB,
and are the key contacts easy to get at and clean ?
Whether you need to unsolder all the keyswitches depends on the keyboard --
there were 4 types, but only one -- fortunately the least common type --
needs much work. The best, and original, was the type using Futaba
keyswitches, which have a white body. These are easy to remove, one at a
time (desolder the connections, then release the clips which hold the
keyswitch in the frame). I've seen a couple of pictures on the web showing
the different types but I can't seem to find one right now :-(
The normal way to fix faulty ones was to replace them. You can still
sometimes find switches available from people who've dismantled machines.
If not, I'd try removing the faulty keyswitches and cleaning them by
swishing them in a small bowl of iso-propyl alcohol, or squirting IPA
followed by switch cleaner through them. Finish with a good-quality
low-residue switch cleaner. These are generally based on IPA with small
amounts of very light oil (not usually silicone, as it creeps too much and
gets into everything). Do not use anything like WD40!
--
Pete Peter Turnbull
Network Manager
University of York