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Pressure Stat failure-Possible reasons.

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  • Pressure Stat failure-Possible reasons.

    Hello Coffee Lovers,
    Just a quick request to those of you how may know:contacts of pressure stat (Rancillio S10/CD two group) failure from severe arching/pitting (see photo).
    Can a failing magnetic relay module contribute to the seriously wrecked pressure stat contacts,or is the problem just due to increasing resistance/heat to final and complete failure of the contacts themselves.
    Will a replacement set of contacts solve the problem,diaphragm/pin/membrane seemed fine and still very pliable/flexible?
    Thanks for your support.
    Click image for larger version

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  • #2
    I call that a shagged pressurestat. The fix? Buy a new one.


    • #3
      G'day mate....

      You'll probably find that the mechanics of the Moving Contacts section isn't operating as 'snappily' as it once did and as a result, the contacts are not breaking as cleanly as they should. Could be down to a buggered diaphragm or just mechanical wear and tear.

      This allows an electrical arc to be maintained for excessive amounts of time and due to the extremely high temperatures of the arc itself, the surfaces of the contacts start to erode due to vaporisation of the parent metal. This doesn't happen cleanly and after a while, the contacts can even weld themselves together... Not a good thing at all.

      Unless you just want to refurb the p/stat as an exercise for experience, a new one is probably the best solution as Chris suggests. No need to opt for the original though, you can get a decent quality narrow band p/stat and connect that in conjunction with suitable SSR(s) to avoid the situation in the future...



      • #4
        Thanks for your reply, thats what I thought, I will proceed with this rebuild, if just for the challenge and as to it's viability.


        • #5
          And if you use them long enough this is what they'll end up looking like:

          Click image for larger version

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          Java "Burned what?" phile
          Toys! I must have new toys!!!


          • #6
            whoa... that looks nasty Java and make the ones in Mick's initial picture look brand new.


            • #7
              Yeah I took those pics a bit over 4 years ago when I had to rebuild the contactor in in my M28:

              Java "Fun with electricity!" phile
              Toys! I must have new toys!!!