From: roger@hayter.org   
      
   On 17 Sep 2024 at 23:11:18 BST, "Cursitor Doom"    
   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   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)