[time-nuts] Racal-Dana tactile switches
Charles P. Steinmetz
charles_steinmetz at lavabit.com
Sun Apr 22 04:41:46 UTC 2012
Stewart wrote:
>It's a design fault and eventually all of them will fail.
I'm not convinced of that. There has been substantial discussion of
Racal switches on the list in the past, and I suggested at one point
that the failure mechanism (dry, cracked "rubber") could be related
to the counter manufacturing process -- in particular, soldering
and/or cleaning of the front panel PCBs. In my experience with 1992s
(quite extensive), I have found that (i) in some counters the
switches never seem to fail, while (ii) if one switch fails in a
counter, all of the others are not long for the world. There does
not (IME) appear to be any correlation with the color of the switch
body or the markings on the switches.
Then again, I suppose making switches that won't survive every
possible abuse during whatever soldering and cleaning processes a
customer might use could be considered a design fault....
Best regards,
Charles
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