[time-nuts] Racal-Dana tactile switches

Stewart Bryant stewart at g3ysx.org.uk
Sat Apr 21 20:04:43 UTC 2012


I know its a hack but I used a small pcb switch and use
a sawn off knitting needle when I wish to press one
of those buttons.

It's a design fault and eventually all of them will
fail.

Stewart

On 21/04/2012 11:58, Chris Stake wrote:
> Just a thought:
> On some equipment, the "push-buttons" are formed by a rubber mat which is
> shaped into domes with or without plastic buttons above.
> If you sacrificed an old calculator it might be possible to cut the rubber
> mat into individual buttons of a size suitable for refurbishing the Tokos
> Chris Stake
>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Ulrich Bangert
>> Sent: 21 April 2012 11:18
>> To: Time nuts
>> Subject: [time-nuts] Racal-Dana tactile switches
>>
>> 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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>
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