[time-nuts] Racal-Dana tactile switches
GandalfG8 at aol.com
GandalfG8 at aol.com
Sun Apr 22 10:22:49 UTC 2012
I made a successful repair of a Racal 1991 counter that I originally
bought as a spares unit, the original switches and switch caps had already been
removed and discarded, but decided after all that it was too good to just
use for parts, especially as all that ever seems to fail anyway are the
switches:-)
As I believe others have also suggested I found that 6mm square tactile
PCB switches could be modified to fit in place of the original Racal switches.
Refitting the original switch caps wasn't an option for me, but whilst
trying to devise some convenient method of operating the normally very squat
PCB switches through the front panel I came across some switches on Ebay
with extended actuators.
Using a switch with an overall height of 13mm allowed the actuator to
protrude approximately 3mm through the panel and this works remarkably well.
It's obviously not totally ideal, one downside for many would be that the
keypad numbering is normally only on the switch caps, although I was lucky
with this unit and the numbers were part of the panel markings, but it did
restore the 1991 to being a perfectly usable counter.
However, given that most users contemplating something similar would
probably still have the original switch caps, and that it shouldn't be too
difficult to refit these to the longer actuators, I think such switches might
provide at least one answer to the problem.
Anyway, I've written up a few notes to go with some photos I took whilst
fitting the switches to my unit and have uploaded these to Rapidshare just
in case anyone might be interested......
_https://rapidshare.com/files/1424161401/Racal1991Switches.zip_
(https://rapidshare.com/files/1424161401/Racal1991Switches.zip)
Please feel free to share or bin this as you think fit:-)
Regards
Nigel
GM8PZR
--------------------------
In a message dated 21/04/2012 11:22:03 GMT Daylight Time,
df6jb at ulrich-bangert.de writes:
Gentlemen,
I know I am not the only one in this group to have difficulties with "weak"
tactile switches on Racal-Dana's 1991/2/6 range of counters. The other day
I
talked to the chief technician at Rosenkranz-Elektronik which is one of the
biggest surplus suppliers in Germany.
He knew the problem very well and his claim was that an exact replacement
for the original Toko switches is no more produced anywhere in the world.
Which may be an explanation why none of us managed to find an exact
repelacement.
His second claim was that the switches can be repared: After removing the
cap gently grip the moving part with a pair of pliers and twist it a
little
bit while pulling it out a bit at the same time. In this way the moving
part
can be removed without destruction of the switch. Then you find the source
of the problem inside: The weak and mostly destroyed rubber part inside.
Replace it with the rubber part of a switch which has NEARLY the same
dimensions. He told me that he had done such a repair for a number of
times.
Unfortunately he had no reference for the switches that he had used as the
source for the replacement rubber.
I am aware that this is only half of the solution of the problem but I
checked his suggestion with a original switch that I had laying around as a
replacement and found that his description worked for me. I made a
photgraph
of the switch to be found here:
http://www.ulrich-bangert.de/Racal.JPG
and perhaps anyone of you has an idea where to get a similar one from. The
problem to find a similar switch is perhaps easier to solve than to locate
a
direct replacement. Note that the scale in the photo is in cm with
subdivisions in mm.
Best regards
Ulrich Bangert
www.ulrich-bangert.de
Ortholzer Weg 1
27243 Gross Ippener
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