[time-nuts] Racal-Dana tactile switches

Chris Stake stake at btinternet.com
Sat Apr 21 10:58:15 UTC 2012


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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