solder on old boards, silver or tin?

Discussion in 'Electronics & Electrics' started by weee ben, Jun 7, 2015.

  1. weee ben

    weee ben Member

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    Hi,

    I'm just trying to work out whether these boards have silver or tin tracing as you see in the picture.

    Under the shiny stuff is copper stenciling, being from the mid 70's when silver was used more liberally, would it be silver?

    [​IMG]

    Other side of the boards have gold wiring across the tops and tantalum capacitors along the base, they didn't really skimp on metals so surely the backs are silver trace?

    [​IMG]
     
  2. Shepete

    Shepete Member

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    It's good old fashioned solder mate.
    Mostly lead.
     
  3. RobRoySyd

    RobRoySyd Member

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    and tin.
    Unusual to find silver being used as it has a problem with migration. Gold, lead, tin and copper are the main metals used for PCBs.
     
  4. O-B-E-L-I-X

    O-B-E-L-I-X Member

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    ...and pure silver requires over 900*C to melt as opposed to solder of ~200-450*C.
     
  5. callan

    callan Member

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    That is a most curious board. What is it from?

    Callan
     
  6. Shepete

    Shepete Member

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    My guess would be a keyboard from an old electronic organ.
     
  7. OP
    OP
    weee ben

    weee ben Member

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    ok thanks, yep it's an electronic organ board, the gold wires bounce up and down to hit the notes I think.

    I just wanted to make sure as I have boxes of 'em and it may of been worth keeping the boards after I took off the gold & tantalum cap's. Normally I just throw cleaned boards in with scrap steel.

    [​IMG]

    The boards are all from the same era, 78-82, and are almost the same except the capacitors, i'm wondering why so many variations?

    Tantalum Capacitors..

    [​IMG]

    What look like hermetic tantalum capacitors but may not be tantalum..

    [​IMG]

    These one's i'm prertty sure are not tantalum cap's..

    [​IMG]

    these either..

    [​IMG]

    These annodised blue one's, not sure but I think are not tantalum..

    [​IMG]

    Although on this board the blue cans are there but also there are tantalum capacitors, the two red ones, so that's probably a better clue the blues are not..

    [​IMG]

    Speaking of that above board, how's this, what appears to be a back plane board, it's got 10 slot cards, I think it's an awesome piece from 70's electronics..

    [​IMG]
     
  8. OP
    OP
    weee ben

    weee ben Member

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    It's a chorus generator matrix, which is another cool thing, using the word matrix is kinda neat.
     
  9. @rt

    @rt Member

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    It’s QA checked in ’81.. not 70’s.

    The chorus board sounds interesting to get going. Being analogue
    I can only guess it delays the source by a bunch of different timings and mixes it all together again.
     
  10. OP
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    weee ben

    weee ben Member

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    I did say 78-82, meaning the QA on boards are dated 1978 - 1982
    the one you see is 1981, yep.

    apparently the chorus boards use analog bucket brigade IC's and could make a cool project for someone.
     
  11. dakiller

    dakiller (Oscillating & Impeding)

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    The first of the capacitors, the red ones, are tantalum. The rest are electrolytic and considering their age, are not worth salvaging at all, unless you were fixing one of these boards and wanted to put a like for like back in, but for any other application, they are junk.
     
  12. rainwulf

    rainwulf Member

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    I would be more interested in the power supply.

    Callan
     
  13. @rt

    @rt Member

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    I’d assume they were used for the next thing rather than scrap.

    Interesting things to look at... would be nice to keep posting finds like this.
    even though in this case, I don’t think I’d salvage anything from them.
     
  14. OP
    OP
    weee ben

    weee ben Member

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    What would the power supply look like? is it like a power board similar to today with chunky transformers etc or something else?

    Ok then, one type tantalum, the rest scrap so i'll go ahead and pick my gold bits off then.
     
  15. Shepete

    Shepete Member

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    Which particular "gold bits" are you referring to?
     
  16. Kafoopsy

    Kafoopsy Member

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    Do any of the boards have white ceramic ic chips? They can be worth up to $15 each to chip collectors.
     
  17. OP
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    weee ben

    weee ben Member

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    The 17 or 22 keys which are the wires sticking from out the board, high quality gold plating and they're about 2.5in long, so 50 inches per board x lots of boards = heaps.
     
  18. 2xCPU

    2xCPU Member

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    I'm reasonably confident the silver sprague caps are wet tantalum (they use sulfuric acid as the electrolyte).

    I agree it's very unlikely the solder is anything other than lead/tin. There is just no reason why exotics would be used.

    2.
     
  19. OP
    OP
    weee ben

    weee ben Member

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    I was reasonably confident them one's were some kind of tantalum cap' myself.
    There's so many variations when it comes to older stuff, I get confused but I did mean to say wet but had hermetic in my head.

    These one's here you might not be able to see clearly are silver/tantalum cap's and have the highest scrap recovery value, around $300 kg..

    [​IMG]

    These one's are hermetic tantalum cap's and they don't have that groove..

    [​IMG]

    These one's have a groove on each side and usually say tantalex so easy..

    [​IMG]

    The second is a wet but see how deep the groove is and see that thickish part sticking out from the left?
    that throws me off a bit as the one's on the organ boards are even both sides..

    [​IMG]

    These I find on older electronics usually made in england, like avery scales etc..

    [​IMG]

    So as you can see, for a scrapper like me it's confusing.
    these are just can capacitors, the resin dipped one's do my head in even more.
     
    Last edited: Jun 9, 2015

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