nixie clock : Pics+Video POST #38

Discussion in 'Electronics & Electrics' started by cyrax83, Sep 26, 2009.

  1. cyrax83

    cyrax83 Member

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    Hey guys, I need to replace two tubes.

    Are they soldered on ? How do i replace these suckers ? I'm ok with soldering, never unsoldered before. I have a soldering iron and solder, i hear I have to buy a solder sucker too ?

    [​IMG]


    [​IMG]
     
    Last edited: Oct 16, 2009
  2. Sleepy Dude..

    Sleepy Dude.. Member

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    i dont think they are soldered, the sockets would be though.

    more likely to be either a twist or a pull.. most likely a pull.

    have you got a picture of the replacement bulbs?
     
  3. OP
    OP
    cyrax83

    cyrax83 Member

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  4. HeXa

    HeXa Member

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    much <3 for nixie tubes!

    would assume socketed
     
  5. OP
    OP
    cyrax83

    cyrax83 Member

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    i've tried pulling a bit on the tube, hasn't budged one tiny bit
     
  6. Sleepy Dude..

    Sleepy Dude.. Member

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    alright, after seeing the bulbs, Its a solder job.

    i'd go with getting a solder sucker too. failing that, a vacuum with a very small sucker nozzle on it.
     
  7. 2xCPU

    2xCPU Member

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    If they were in sockets, you'd pull vertically (NEVER twist).
    But they look soldered to me.

    Can you find someone else to unsolder them?
    13Pins is not ideal for a beginner (all too easy to tear a track off the board).

    With some shielding to protect the rest of the board, a hot air gun would work well.

    2.
     
  8. itachi46

    itachi46 Member

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    while you're at it get a socket :p so you dont have to repeat this
     
  9. OP
    OP
    cyrax83

    cyrax83 Member

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    Hmm don't know anyone who isn't a beginner at using a solder either. I do agree, taking a closer look at the 13 pin solder, it does look pretty tiny, they are very close to each other and the tracks.

    I dont think they have sockets for IN-14 tubes ... and the way the enclosure is designed, the tube height needs to be identical as what it is now so the tubes will stick out of the enclosure at the right height and the enclosure will just cover the white area.

    Also guys, will this solder sucker be good enough from jaycar ?

    http://www.jaycar.com.au/productView.asp?ID=TH1850&keywords=solder+sucker&form=KEYWORD $7

    Or i could spend $12 and get this one from dse http://www.dse.com.au/cgi-bin/dse.storefront/4abd994f01ec2ce02740c0a87e0106bd/Product/View/T2567
     
    Last edited: Sep 26, 2009
  10. MyDixiesNormous

    MyDixiesNormous Member

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  11. warez_kid

    warez_kid New Member

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    lots of flux
    a nice hot iron with a clean tip
    a solder sucker

    go slow

    don't use desolder braid you'll rip up the tracks.

    If you want to be a bit adventurous you could probably use a hot air rework station.
     
  12. OP
    OP
    cyrax83

    cyrax83 Member

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    It's second hand so no idea how long it's been used for.
     
  13. 2xCPU

    2xCPU Member

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    In that case, practice a lot first.
    Get a dead Mobo, VCR off hard rubbish - anything with a board to play with.

    Another hint is that often you get to a point sucking the solder and you just can't get the last bit. It often helps to resolder the joint and start fresh. Often it will clear first time after being resoldered.

    2.
     
  14. MyDixiesNormous

    MyDixiesNormous Member

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    Put the braid between the iron tip and the part. Heat the solder via the braid. Pull away as soon as its done its job. I cant imagine how incompetent you would have to be to physically rip off tracks.
     
  15. RobRoySyd

    RobRoySyd Member

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    Looking at the board it's a plated through hole board. Desoldering multipin components isn't so easy on these kinds of boards as the solder really likes to stick between the pin and the copper tube in the hole. On the plus side it's more difficult to lift a pad on a PTH board.

    What I've always done is to free the leads from the component. Then heat each pad one at a time and gently ease the pin out of the hole. Then it's quite easy to heat the solder and suck or blow the solder out of the hole. The latter seems to work better.

    Freeing the pins is going to be tricky with these tubes. I'd wrap something around the tube to be replaced. Masking or gaffer tape would be good. Then rest the tube on a piece of metal making certain the other tubes aren't touching anything then give it a whack with a hammer. Wearing eye protection would also be advisable just to be sure.
    Then I'd use a pair of bull nosed pliers or large side cutters to shatter the glass from the pins. Actually one of the replacment tubes seems to use stranded wire. Once all the pins are free the job is much easier. Dispose of the dead bits and glass carefully. Some of those old tubes had nasty shit in them, who knows what the Ruskies were using.
     
  16. OP
    OP
    cyrax83

    cyrax83 Member

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    Instead of shattering the glass, what about getting a knife and slowly removing the white padding, then chopping off the glass half of the tube at the base. Could then melt the solder at the bottom of the board then pull the wire out with some pliers ?
     
  17. nvinen

    nvinen Member

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    I find the best way to desolder a multipin device from a PTH board is to first use a solder sucker to remove most of the solder from each joint - set the soldering iron at around 400C and add flux if necessary. Then patiently apply solder wick to each pin, adding flux if possible, go over each pin several times. Eventually once you've soaked up enough solder the device should come loose. Don't pull on it hard.
     
  18. RobRoySyd

    RobRoySyd Member

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    I did think of that initially however you'd probaby need to use a jewellers saw to get between the sockets so you could cut through that plastic. It could be quite tough. My other concern with this approach was you could still end up breaking the envelope so I figured it actually safer to break it having taken steps to contain the glass.


    A tip if I may.
    The less time you keep solder in its molten state the better for the joint. Solder works because copper dissolves in solder to form a copper/tin/lead alloy. This is a very thin layer and one that cannot be removed by sucking or blowing. It's like trying to vacuum shit off a blanket.
    This extremely thin layer is very brittle. The longer the solder is at high temperature the thicker it becomes and the weaker the joint will be regardless of what you do as you cannot remove this layer. You might make the joint look prettier but pretty does not equal strong or reliable.
    If my memory serves me well the migration of copper into the solder even continues at room temperature although extremely slowly. This explains why old valve gear from the early days can have solder joints that just fall apart.
     
  19. dakiller

    dakiller (Oscillating & Impeding)

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    I don't think that is right at all, It has always been my experience that this brittle layer is oxidisation and that it is always easily fixed by adding flux back in to the molten solder. Anyway, this is hardly an issue for the OP, as once the sockets are out he will be removing any excess solder from the PCB anyway.

    With a plated through-hole board like this, it is pretty much impossible to remove all the solder in the holes around the pins, and because I have a hot air reflow station I would be using that to just melt the solder and slowly work the tube out, adding fresh 60/40 solder and lots of flux along the way. You have to be careful at how hard you pull, as the through-hole plating is easily ripped out. With the hot air station, it should just be a matter of securing it upside down and keep heating it until the tube straight out drops out under its own accord.

    For someone who hasn't done some serious desolding before, I wish him luck and expect to break some part of the PCB along the way, lucky this is just a simple double sided board and if you break a track it isn't hard to just fix it with some small wire and wire from the tube back to the headers
     
  20. RobRoySyd

    RobRoySyd Member

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    Point was that the longer you keep the solder hot for the more copper leaches. You cannot easily remove the bonded copper/lead/tin layer. The oxidiation that you refer to is on the outside of the solder. That will be removed by a flux. The layer that I was referring to lies between the copper and the solder. Short of sectioning a joint and looking at it with an electron microscope you'll not see it. There's not much information around about this, I sat through a two day seminar with the guys from HP and Tektronix to learn this. That was decades ago when we were looking at fluxless soldering options. There's some reference to it here:
    http://www.electroiq.com/index/disp...e-4/s-features/s-the-basics-of-soldering.html

    Just found a better reference including micrographs:

    http://journals.cambridge.org/downl...02a.pdf&code=7a2c1566b9890910d4063bbf512011e1

    One of the points made many times by the speaker from HP was that almost everything taught about soldering in colleges and put into practise on production lines, by inspectors and at rework stations is wrong.

    And yes, sorry this is getting a bit off the OP's topic. My apologies but I keep reading advice given many times that fails to factor this in.
     

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