Re: Switch Contacts

On 17 Sep 2024 at 23:11:18 BST, "Cursitor Doom" <cd999666@notformail.com>
wrote:

On Sun, 15 Sep 2024 22:46:18 -0700, John Robertson wrote:
 

On 2024-09-15 9:44 a.m., Nick Hayward wrote:

Hi all,
 
I have a switch which isn't making electrical contact. It consists of
two leaf springs. Dead simple. They're springy enough to push against
each other alright. And I've cleaned them with ethanol (didn't work)
isopropyl alcohol (didn't work) and Servisol switch cleaning lubricant
(didn't work either). I am at a complete loss here. Has anyone come
across something like this? I can confidently say I never have!

 
Have you verified that the meter leads are making good electrical
contact to the switch blades? Oxidation can fool any of us! Touch one
probe to the switch blade, and touch the other probe further down the
blade - repeat on the other side, only then check for electrical contact
closure once you are certain you have good probe connections.
 
John :-#)#

 
Acting on the advice of someone very much more experienced with this
attenuator  than I am, it's the case that the offending material was
silicon oxide. Something to do with contact sparking and silicon grease
that they used in the early versions of this device. The only remedy is
fine abrasive paper. I used 1500 grit in then end; very lightly just a few
strokes. it's fine again now - and before anyone says anything, there was
no gold plating on these contacts to rub off!

Not to criticise your decision (which I actually suggested) there are lots of
other contact plating materials than gold. Some of them are thicker or softer
than others. Apart from other noble metals, nickel and tin spring to mind.


--

Roger Hayter