repair of thermal arc stick and tig

  1. angellonewolf

    angellonewolf Member

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    ok as today i accuired(thread) a bit of time to have a look at a few projects

    one is what i hope to be my new stick welder as it adds in the possablity of dc tig (when i get a torch for it) a thermal arc 175se

    now the problem its been droped and snaped the pcb 20200616_104911[1].jpg 20200616_110317[1].jpg 20200616_104511[2].jpg

    ok recived a thermal arc mma tig welder broken non working for very little money

    as can be seen ive found a dodgy power switch sorted that ish (needs sorting but a new switch has been insalled but the hole its in its a bit loose but thats not the problem )

    but on closer inspection i found a broken/riped pcb (prob because its been droped)(i was told it was working then it was not so its not a supprise)

    now there are 4 tracks 2 on one side 2 on the other the pcb is bent and cracked

    ive done a temp cheak removed the broken tracks and put in links and powered on and is working fine (me and son run a few rods tonight before posting this)

    but now its working (prob not after i have another go at it but the break is where the board is held in the case (why it prob broke as it was prob droped )

    but now the question how to repair the board and install new tracks that the board is strong and the tracks safe

    my first thought is (as i expexted remove temp links as only put in there to test as dont want to do a big job to be disipointed it dont work but now i know its working its worth having a go)

    so remove temp links cut board epoxy the joints and run the links over the new fixed board ans seal them to prevent any shorts /

    so questions

    how to repaire the board the pcb cut out replace ? or try fix whats there ?

    solder new links in place the ones in pic look big enought to add to the tracks (dont want it burning out)

    and is any repair on this bit going to last ? as its on a stress point

    could i tag @HughF ive seen hes done one before on such stuff and any help info would be great from the fourm any input would help over the years ive done a fair bit of component repairs but never tryed to fix a pcb or work on such a powerfull unit so need advice on if links are ok


    thanks for any help
     
  2. MoreWellie Member

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    1,149
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    if you didn't mind being a little bit heath robinson, from what I can see I would do one of two routes

    straighten the broken piece as much as possible
    strengthen with fibre glass resin (and mat if it wouldn't make it too thick)
    complete the tracks with suitably heavy flex
    or
    trace the existing shape
    cut the tracks away and remove the broken piece of board
    make up a piece of ally to fit on the remaining board which appears to have no tracks on it and bend it so it occupies the same shape as the previous board
    you could then complete the tracks with suitably heavy flex rather than solid copper
     
  3. angellonewolf

    angellonewolf Member

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    straighten the broken piece as much as possible
    strengthen with fibre glass resin (and mat if it wouldn't make it too thick)
    complete the tracks with suitably heavy flex
    or
    trace the existing shape
    cut the tracks away and remove the broken piece of board
    make up a piece of ally to fit on the remaining board which appears to have no tracks on it and bend it so it occupies the same shape as the previous board
    you could then complete the tracks with suitably heavy flex rather than solid copper[/QUOTE]


    thanks for the reply this is the reason im posting ive not tryed to push back the broken bit as of yet as wanted to see if it ws working before playing much in an ideal way id like to repair what is there by pushing it back flat (im assuming glueing or epox) but the way its broken im not sure its going to just bend back as it looks like it split a bit like fiberglass what the reason i was thinking if i could cut a slot with a junior hacksaw bit if i use this is the board going to glue back together as even with a thin blade there will then a gap that the glue will have to bridge this why posting as need experance in this

    ive not even said about one part of the track is just floating over the board as what ever i do this needs laying back down and sticking with something my first thought was superglue but as ive got to solder after im not sure thats a great idea

    20200616_104511[2].jpg

    im not adverse to cuting a chunk out of the board and reseating some thing in there if i have to but im not sure a piece of metal with all the eletrical stuff and high voltages and amps seam that safe to me ? but again why asking for expert help on finding the solution
     
  4. barking mat

    barking mat Barking at Pigeons

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    Superglue?
     
  5. angellonewolf

    angellonewolf Member

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    was my first thought but after a quick google search

    Epoxy and Super Glue are popular names for products that cover a broad range of adhesives used in home and industry. Each has a specific chemical composition and best recommended uses. They have a few applications in common, but are most effective when used for their intended purpose.

    What is the Difference?
    Epoxy is a compound made from two parts that the user must combine: a resin and a hardener. The user then has a specific time, based on the package formulation, in which to use the glue before it hardens. Super Glue is a single component made from cyanoacrylate that hardens rapidly with exposure to moisture in the air.

    Properties
    Both form a very strong bond. Super Glue, however, has very low shear strength which means that the parts bonded will resist direct pulling but not off-angle stress. Epoxy, on the other hand, has tremendous structural strength. Epoxy is better at filling voids between parts. Some varieties of Super Glue include additives to fill small voids.

    Uses
    Epoxy, in its many formulations, is used as an adhesive, a coating for metal and composites, insulation of electronics, model making and many industrial applications. Super Glue is utilized on a much smaller scale, but in applications that vary from surgery to small parts assembly, and it is even used as a wood finish.

    Clean Up
    Epoxy, before it hardens, may be removed with acetone or white vinegar. Once it hardens it is very difficult, if not impossible, to remove without damage to the surface it was applied to. Super Glue can be removed, in either liquid or solid state, with acetone (nail polish remover) or gamma-butyrolactone (GBL). GBL may be preferable because it is less toxic.

    https://www.hunker.com/12252320/what-is-the-difference-between-epoxy-super-glue

    from the first web page that come up

    if this is right super glue a twisting action breaks it more easy as its where the board is held in place by a plastic tab on both sides and when you lift or knock it this might happen ?

    thanks guys for all input keep them coming
     
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  6. arther dailey

    arther dailey Member

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    If it works why go further? use as is surely
     
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  7. barking mat

    barking mat Barking at Pigeons

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    Don't drop it again...

    I appreciate it wasn't you.
     
  8. HughF

    HughF Member

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    What's the problem here - that repair is 100% legit... cover back on, fire it up!
     
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  9. angellonewolf

    angellonewolf Member

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    i have used it to prove its working as ive posted above in number 3 thread ive outlined the bit where ive soldered but the track is just floating so any movement will easy break the connection and at the moment i dont know but assume its going to the 2 surface mount r202 and possably r201 but if not and that track breaks im in the dodo repeat of pic so this defo need fixing back to the board with resin or superglue ? also the wire at the moment is not covered so is not free could or should possablely need a coating of something to seal to stop anthing shorting and to stop the copper from rotting ?

    [​IMG]

    see the bit where ive marked it that is floating in mid air so could be easy tore off (it looks attached at the moment but it not )

    20200616_104911[1].jpg


    this is the opisite side of the board ive marked the plastic tab ( that once you put the front on it where it holds) that the board sits in and only just by a few mm keeps the board in place (see the arrow in yellow where black is on the pcb where its rubbed) there is a lot of weight on this board (i will try to post a pic if i got one on my phone found one
    15923332112064130315753474301989.jpg

    as you can see from the photo all of the weight is on that board stood up and the only thing stoping it from flexing is this tab be be honest its a bit of a carp design

    so if it got knocked or even when carryed the case will flex and move the board (there bell wire solid at .56mm this will not flex so would pull on the tracks on the board) as ive got a working one now would like to keep that way

    thats why i was thinking of doing a more proper repair not just for at the momment a test repair

    im thinking ive seen on the fourm someone did do a pcb repair( i tryed but cant find it would be nice to read that again to get ideas) and was hoping to do the same on this as a perment repair as its a quality mechine and its welds realy nice and does tig as well it will be my go to mechine so dont want to spend hundreds on it as cheap a repair as possable would be nice but not just a quick throw together as ive done at the moment
     
  10. MoreWellie Member

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    1,149
    Location:
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    You are correct in that method needing care but the circuit board looks remarkably clear of tracks in that area which was why I thought this could work. There certainly won't be high amps and probably not high voltage in that area of board but I don't know that specific board

    if the broken area of board isn't actually used to locate it then I would agree with @HughF

    If you want to secure a bit of floating track I would solder the connection to it first and then glue over the top, if you stay with the heavy wire rather than flex you could stop movement by glueing the wire in the middle rather than over the soldered part

    I would probably use hot glue gun to secure it down but you could also use epoxy

    as long as you don't make unnecessary connections then whatever solution should work fine
     
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  11. MoreWellie Member

    Messages:
    1,149
    Location:
    Bedfordshire, UK
    ok, having seen the last picture I probably wouldn't put any metal in there to strengthen the board but that does limit you

    is the slot big enough to get a layer of plastic glued along the circuit board?

    whatever you do will be weaker than the original but gentle treatment could see that working for a long time yet

    have you checked the cost of a replacement PC?
     
  12. barking mat

    barking mat Barking at Pigeons

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    drill a small hole at the end of each track and solder in jumpers, then remove broken bit.
     
  13. angellonewolf

    angellonewolf Member

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    yes this is the problem (as above ) this cut out is the mounting point of the board to hold it steady so why i think it needs fixing properly
     
  14. barking mat

    barking mat Barking at Pigeons

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    what about liquid plastic glue, used in modelling? anyone know the trade name, that's good.
     
  15. barking mat

    barking mat Barking at Pigeons

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  16. angellonewolf

    angellonewolf Member

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    the slot could be made a little bigger but not much the pins that go over the pcb are only 4mm thick either side so what i remove will weaken the hold on the board

    not cheaked the cost of replacemnt but i expect it to be £50 or £100 as parts for most stuff seams to be way over priced and some of the stuff could be removed but that would leave a lot on there so expect price to be near the higher amount



    cant do this as the board where its split is what mounts it in the case if i removed would need replacing
     
  17. angellonewolf

    angellonewolf Member

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  18. barking mat

    barking mat Barking at Pigeons

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    i'd stick it where the edges of the board meet, it seems eat into the plastic and weld it together.

    Mek Pack - or something was the trade name I was thinking of?
     
  19. arther dailey

    arther dailey Member

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    solder muti core wire to act as jumper cable, to bridge crack area.
     
  20. angellonewolf

    angellonewolf Member

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    can you use solder to join im sure as soon as i put an iron to the solder it will a pool of molten metal and is solder not quite soft ?
     
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