MIG welder problem - help sought

  1. Benpointer

    Benpointer Member

    Messages:
    33
    Location:
    Dorset, UK
    Hi there, hoping someone can advise on this issue I am having.

    I have a Migatronic 180MX which I bought secondhand a few years ago and I use about 2 or 3 times a year. never had any problems with it, very easy to use. I am a very occasional amateur as you can guess.

    Today I was welding up a fair bit of 30mm x 3mm mild steel box. It was fine for most of the day but late on this afternoon I had to stop as the welder was not maintaining any sort of arc. It was almost as if it has gone into a very low powered stitch mode (I checked, it was definitely still set to continuous seam weld).

    I counldnpt see anything obvious - the shroud, nozzle and wire (0.8mm) all look fine, gas is ok, the welder doesn't feel hot or anything. I was welding happily on a power setting of 5, wire speed 7, gas rate 10 all day. I am using argoshield lite.

    Bit of a mystery. Will have another go tomorrow but if anyone has any ideas, that would be great.

    Thanks
     
  2. Rig Pig

    Rig Pig Member

    Messages:
    3,755
    Location:
    Narrwich! U.K.
    Check the capacitor bank, mine failed a few years ago, I put a thread up on here about replacing them.
     
  3. Rig Pig

    Rig Pig Member

    Messages:
    3,755
    Location:
    Narrwich! U.K.
  4. Tom O Member

    Messages:
    293
    Location:
    Canada
    When my bank went on the Miller it let out a lot of smoke!
     
  5. eddie49 Member

    There may be a loose, corroded, or burnt connection in the high-current welding path, causing a high resistance, and this has heated up during extended use and become worse.
     
  6. Fazerruss

    Fazerruss Member

    Messages:
    2,619
    West Yorkshire
    I have the same machine. As said check the capacitors as one may have died. Mine went pop after 24 years so couldn't complain!
    Make sure you the replacements are fit for purpose, they need to have a high ripple current for welders. I got mine from TecArc for about £60. Other possible cause could be a diode failure in the rectifier.
    They are a well built little machine and easy to repair.
     
  7. Benpointer

    Benpointer Member

    Messages:
    33
    Location:
    Dorset, UK
    Ok thanks for the replies everyone... I will have another try this morning and if it's no better I now have a few lines of enquiry to pursue.

    Much appreciated!
     
  8. Benpointer

    Benpointer Member

    Messages:
    33
    Location:
    Dorset, UK
    Ok still no joy this morning. Took a look inside, it's a bit dusty but I cannot see anything obviously blown or corroded etc.

    Not sure how I would check the capacitors - not keen to spend money on new ones if the problem is something else.

    Will post a few photos...
     
  9. Benpointer

    Benpointer Member

    Messages:
    33
    Location:
    Dorset, UK
    Capacitors - no obvious signs of damage/corrosion:
    [​IMG]
    [​IMG]

    How it was welding yesterday morning (ok, I am not the world's greatest welder :laughing:)...
    [​IMG]

    And how it wasn't welding once it went wrong - just a quick splutter, then nothing:
    [​IMG]
     
  10. eddie49 Member

    Are you sure that the Euro torch mounting at the machine and the welding return lead ( earth cable and clamp ) are making good connections?
    Do you have a second Euro torch to test with?
    Do you get low welding power at all settings of the power range switch?

    The next step would be to measure DC volts between the torch tip ( positive ) and the earth clamp, with the trigger pressed. Shut off the gas valve and slacken off the wirefeed pressure roller. The voltage should start at about 16v on the lowest setting and rise to about 30v as you step up the power ranges.
    If you don't get that sort of result, then it will be time to start disconnecting cables around the transformer and the rectifier, to check the secondary AC voltage and test each of the diodes.
     
  11. Appyasme1

    Appyasme1 Member

    Messages:
    1,389
    Location:
    Lancashire
    Sounds to me like diode fault
     
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