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Mig wire welds without hitting the trigger?

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  • Mig wire welds without hitting the trigger?

    Hi everyone, new to the forum, just picked up this sweet Millermatic 210 mig welder and the problem I'm having is when you touch the wire to the piece your working on the thing arcs before you hit the trigger. and its not just a short arc, the wire will try to weld. I replaced the trigger switch already and I'm not sure what else it could be. thanks for any help.

  • #2
    Mig wire welds without hitting the trigger?

    I'm not familiar enough with the 210, but on some entry level machines the wire is always hot. A friend of mine got a small wire feed welder, pretty sure it was a 115v, and it welded fine but the wire was always hot like that. I did some research and found that there are a lot of machines like that. Again, not sure if the 210 is supposed to be like that or not.


    • #3
      I have a mm210 that I purchased new many years ago.

      Just after completing a weld, the wire is still a little "hot" for a few seconds - just enough to make a tiny spark if touched to the work, may even stick a little.

      But it is not hot all the time - if yours is, I'd take the cover off and check the contactor - it could be stuck in the closed position.
      "Beware of false knowledge; it is more dangerous than ignorance." ~George Bernard Shaw~

      Airco 300 Heliwelder
      Dialarc 250 AC/DC
      ESAB 161
      Invertec v250 and v300 Pro
      Spectrum 700 plasma
      Miller HF-15-1
      Dirty ugly tools - perfect


      • #4
        Does it stay "hot" or is it just a single strike that's "hot"? Could be an open bleed down resistor. I only looked at the most recent owner's manual but it looks like resistor R1 in the diagram and possibly item 21 in figure 9-1. I'm not a welding machine tech but I would check that and the connections on the output wiring. Post your serial # and Cruizer can likely tell you where to look.---Meltedmetal


        • #5
          Bringing this back up from the dead. I have an older MM210 SN le410070. I have been experiencing the same problem. The wire stays hot and will arc when it touches the work piece. Entirely frustrating as it often will stick to the tip.
          Thanks for the help.


          • #6
            If it is more than just a little spark, then look at your contactor to see if the contacts are stuck together.


            • #7
              I have seen a couple come through here where the signal from the main PCB held the contactor in if the contacts are closed without being arced check if you have 24 volts AC at the coil. If the voltage is there without pulling the trigger PC1 is bad. But most are arced closed.
              Replace contactor P/N 189486


              • #8
                You basically have one of three scenarios.

                1. Agree with walker, if it is a little spark and then the voltage goes away, it is most likely the Capacitor Bank voltage is not being bled down by the Bleed Resistor (R1). This bleed down does take time, so there is voltage present at the output studs right as you stop the previous weld. But this should bleed down relatively quickly.

                2. If however, the voltage is present all the time at the MIG gun, then the connection points in the Weld Contactor (W) could be stuck closed and this item just needs to be replaced. This is assuming that there is NOT 24 VAC at the wires that control this contactor, wires #14 and #15.

                3. If there is 24 VAC at #14 and #15 of the contactor coil (W) AND you are not closing the gun trigger, then the control board is likely defective and is always sending the voltage to the contactor coil even though the gun trigger is not closed.

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