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Strange Plastic degredation/copper oxidiation phenomina on mains connected leads?

Discussion in 'Electronics & Electrics' started by mAJORD, May 12, 2020.

  1. mAJORD

    mAJORD Member

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    Hi All. I have a couple of strange finds , or at least strange to me. Wondering if anyone's seem similar.

    A few months ago I was underneath the desk in my retro room, and unplugging/ plugging in things when I noticed one of the IEC leads was incredibly sticky and greasy around the mains end. looking at it closely I noticed this..

    it seems to be oozing something out from where the pins enter the moulded plug Looks like a copper oxide of sorts.. On the power board where it was plugged in (facing down) is like a small puddle of oil .

    It's a pretty old lead, so I dunno, age related breakdown, perhaps, though doesn't really explain the reaction with what I assume are plated copper conductors. And why only on this one end? (the small end is fine, not any way sticky either)

    Exhibit A.

    IMG_20200512_131749 (1).png


    Interesting on it's own I guess. Today though I discovered this when moving some stuff on my Workbench:


    IMG_20200512_131634.png
    It's the wrist strap socket for my ESD mat it also doubles as the earth connection point to the mains. (via a proper fitting)


    Supposed to look like this.

    IMG_20200512_132335 (1).png




    As you can see the plastic has completely hardend and disintegrated, and can't have been THAT long ago either as I do every couple years maybe check the connections even though I rarely use a strap anymore. It's probably only been plugged in there for about 3 yrs anyway

    It also has a green substance wherever the plastic and metal has interfaced, and looks identical to that on the mains lead. along with that a white powdery substance.. it's like something has caused a combined corrosive/ oxidising effect on the copper, and degraded the plastic (albiet in different ways)

    Side by side:
    IMG_20200512_143254.png



    I can't find any reason to think the occurrences are connected, but I do find the similarities odd. including being on the same wall of the house (but seperated by a room) and obviously the apparent oxidising effect? and both being plugged into mains
     
    Last edited: May 12, 2020
  2. _zak

    _zak Member

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    My immediate thought is solvent damage - do you use anything for cleaning etc. when working with the retro gear or electronics? What type of wall is in between the two rooms, and can you check the roof space above it?
     
  3. HSV_Enigma

    HSV_Enigma Member

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    I have seen this exact same damage on the same style of grey moulded lead, I figured it was a bad batch of plastic reacting with the pins.

    While you have it all exposed put 2 resistors in series as they are generaly only rated to 250v, an open earth surge could be more than that.
     
  4. OP
    OP
    mAJORD

    mAJORD Member

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    No, that's the thing.. especially my retro stuff, I wouldn't even go in the room with anything remotely solvent like haha.

    The ESD bench is all PC stuff . occasional use of alcohol to clean a CPU, that'd be the extent of it.


    You're talking about the IEC lead first sentence yeah? That's interesting. Seems like might be just the case with both

    I won't be bothering to do anything with the ESD socket , Got that new one.
     
  5. merlin13

    merlin13 Member

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    Chemical degradation of some sort.

    Unlikely, but the ESD connector "could" have been heat related as well perhaps.

    Regardless, stating the Bloody Obvious for the Young Players signing on here - Do Not Lick Your Fingers after coming into contact with those bits.

    That could also be the result of the chemical degradation, but more than likely that stuff its actually an oil of some sort. Possibly even a mould release or external contamination from the original manufacturing process, seen that a few times...

    Where you say "retro room" as well, "retro" as in you fiddle with Olde Schoole electronics? Also unlikely but if so be aware that oil could also be some of the toxic/carcinogenic nasty stuff they banned yonks ago out of old capacitors etc...
     
  6. ArmoureD

    ArmoureD Member

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    Agreed with the above posts.

    I've come across fixed mains wiring from the 70s and maybe 80s that has the exact problem.

    It's the plasticiser in the pvc reacting with the copper and oozing out, leaving the pcv to become brittle.
     
  7. Symon

    Symon Castigat ridendo mores

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    Olex released a statement about this a while ago -

     
    heller44, Fred Nurk, mAJORD and 4 others like this.
  8. OP
    OP
    mAJORD

    mAJORD Member

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    Awesome, thanks guys!

    That explains both really. I guess the esd socket has lost all it is plastizier already for Whatever reason ( because it's shite I guess) and already turned brittle, but had reacted with the copper at some point
     
  9. aXis

    aXis Member

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    Just wondering if there is some DC bias in your AC that is also leading to electrolytic reactions.
     
  10. JamesR

    JamesR Member

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    I have this problem with some of my light fittings. Luckily I have enclosed glass covers, so every-so-often I give them a clean.
     

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