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  • Toasted my TIG machine - help? :(

    Decided to fix a problem I didn't really have.. and now I'm out a nice
    150amp AC/DC tig welder. Man I feel like crap.

    Homebrew foot controller worked fine.. didn't have the full range (couldn't
    get down to below 10amps and couldn't get past 140 or so).. because
    of the way the potentiometer mech in the foot pedal worked. (cosine error )

    Anyway, bored one day, decided to finally "fix" it.

    And boy did I.

    Made a new pedal (all metal this time, no plastic crap) and was "tuning in
    the range" of the pot with the pedal on my bench -- the same bench
    I had the torch/ground rigged to along with the ammeter!

    ps.. here's a vid of the pedal.. turned out pretty nice I think.

    Sh*t -- and I thought $300 for the OEM pedal was highway robbery.

    http://www.youtube.com/watch?v=nzKuQQKcclM


    So long story short I think I had a short in the on/off switch in the pedal
    (to the metal casework) and I think I sent HF/HV up into the machine.

    Now here's the crazy part.. I've been told HF/HV back to the machine
    causes MAJOR damage.. but the whole machine works just fine except
    for one little small thing: I can't get any more than 5 amps out of the
    box!

    Arc strikes and is stable.
    Up slope / down slope works fine.
    I can selected AC / DC / Stick / Pulse / Freq, everything.. but the amp
    control on the box is gone.

    Called the mfg (Cemont).. they told me it was a bad control board.. $250.
    ORdered it, waited 2 weeks, put it in.. nothing has changed.

    Called them back: "Well we have no idea where HF/HV might go send us the
    machine but probably needs a new mobo" which is something like $600 + labor.

    Machine is (WAS) worth $2k. I don't have the money to throw into it.. its a hobby
    I don't know how I even managed to buy it the first time.

    So I'm going to dig in myself.

    Anyone out there into electronics and know anything about inverter style welders?
    Looking for tips / things to look for / etc.

    First I got to figure out how to safely discharge these large caps with the sticker that
    reads: Discharge me or die!


    Tigless Tony
    Last edited by Tony; 05-25-2012, 05:17 PM.

  • #2
    Originally posted by Tony
    Made a new pedal (all metal this time, no plastic crap)
    here's a vid of the pedal.. turned out pretty nice I think.

    http://www.youtube.com/watch?v=nzKuQQKcclM
    I can't help you on the control board, but wow -- that's a very nice foot pedal mechanism!
    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

    Comment


    • #3
      Tony,
      Try here.

      http://www.mig-welding.co.uk/forum/index.php

      Brit forum but some very clever people on there.
      .

      Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



      Comment


      • #4
        I often discharge caps that are low voltage (less than 440v) by using a light bulb placed in a temporary pigtail socket. Just touch one wire to each side of the capacitor. The lightbulb will light briefly and fade out as the cap discharges. If the bulb blows (excess voltage) use two in series. It sounds like your machine is putting out the minimum amps and I would suspect whatever got fried was what was first in line where the pedal plugs into the machine. Look at the portion of the circuit first. Look for burn marks from diodes, ICs and resistors. Have you checked the machines output with your foot control out of the circuit and deselected on the machine? Maybe you cooked the foot pedals potentiometer causing the machine to default to lowest output.

        Comment


        • #5
          I have exactly this problem on my tig, but its a old relay based sinewave set from the dawn of time.
          I lost power from the amps control in all modes and it just gave base output selected on the range selector, first I checked out the contactor which throws in when you trigger the tig torch , bad contact and a clean up did that good, then found a relay burnt and not switching the contacter in.
          Ive now got full power control back on MMA because the selector switch for the machine bypasses the latching trigger/pedal circuit which I think still is damaged, but still no tig. But I came in with sore eyes after tracing wirewrap loom for 3 hrs.
          Mentioning it because I think its how tig's are architected, and even though they're completely different you have to work on the modern equivalent section of the circuit to my relays and wires...

          Comment


          • #6
            Thanks guys.
            John, I'll have an ask over there too.
            This is an italian machine.. and I'm here in Italy.. funny thing is the
            only one who'd even talk to me was a chap named Paul at Telford group
            in UK. Great guy.

            We cemont told me it was the analog control board I spent a whole
            day taking it apart, piece by piece and checking. Checked out fine, but
            I'm not EE. I should've trusted myself.

            There are two sets of wires: torch switch and pot.

            They all go to the analog board first, then the logic board below it.
            Nothing is burnt/blow (first thing I looked for).

            Thing is, the switch leads also run elsewhere (jumpers) and go deep into
            the machine.

            They really pack these things tight!

            I'm hoping to find something obvious when I dig in.

            And I just ordered a new CK 9 and 17 with superflex cables!

            Tony

            Comment


            • #7
              nice pedal... lovely job ..that's precision ..i like it .

              I'm scared to death of anything electronic ..not afraid of the shock from the electricity ..but the price to fix .

              my tig has transformers ..and a big windy handle ..and Doctor Frankenstein Hi Freq - jump the gap - generators.

              bullet proof ..and hopefuly "fool" being myself ..foolproof.

              OH.. IT'S ITALIAN AS WEL...L CEBORA

              all the best..markj

              Comment


              • #8
                yeah some of those older Cebora are bullet proof.
                I've got an old plasma cutter thats been to heck and back..
                probably full of 10lbs of slag and still works like a champ.

                Consumable are expensive though.

                Best I can tell the only "digital" part of this welder is the logic
                board. And I'd imagine HF/HV spike would've blow the surface
                mount stuff to kingdom come.

                Rest of it is all big transistors and transformers.

                If nothing else this is a good excuse to finally pick up an old
                oscilloscope.

                How do they design these things so tight? I'm surprised air
                can even make it through this machine.

                Tony

                Comment


                • #9
                  Originally posted by aboard_epsilon
                  nice pedal... lovely job ..that's precision ..i like it .

                  I'm scared to death of anything electronic ..not afraid of the shock from the electricity ..but the price to fix .

                  my tig has transformers ..and a big windy handle ..and Doctor Frankenstein Hi Freq - jump the gap - generators.

                  bullet proof ..and hopefuly "fool" being myself ..foolproof.

                  OH.. IT'S ITALIAN AS WEL...L CEBORA

                  all the best..markj
                  That's the one of mine that's broken...............
                  .

                  Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                  Comment

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