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Xmt 300 cc/cv help

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  • Xmt 300 cc/cv help

    I bought a used xmt 300 cc/cv and took it to a local welding shop to have looked over and checked out. They gave it back to me and said everthing was good to go. I plug in the welder tonight for the first time and hooked up my tig tourch, ground cable and foot pedal. I fliped the switch and it turns on and runs but when i try to start welding i get nuthing. It dosn't seem like it is tring to start an arc. I pulled the top cover off and see nuthing out of the ordaniry. Where would be the best place to start looking for a problem.
    thanks joe

  • #2
    I have an XMT304 CC/CV, which is somewhat similar to an XMT300 CC/CV.

    Are you trying to scratch start with it?

    The machine doesn't have HF start. I don't think it has lift start either, not sure. Most likely, you'll need to scratch start it, like striking an arc with a stick electrode.

    Are you using a pedal or hand control with it?

    On my XMT 304, there is a panel/remote current control switch. It must be in the remote position to use the pedal and the Mode switch must be in the remote-tig position, which switches it to constant-current output and allows use of the 14-pin remote connection for contactor and current control.

    To use it with a pedal, put current switch in Remote position and mode switch in Tig-Remote position, select maximum current desired with the panel current control, hit foot pedal, scratch start and weld.

    To use it without a pedal, put current switch in Panel position and mode switch in Tig (no remote) position. Set current desired with the panel current control. Torch is always hot like a stick rod. Scratch start and weld.
    Last edited by Desertrider33; 09-11-2009, 11:37 PM.

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    • #3
      Give us more specifics. I presume the XMT is set up for single phase 220v. power and that you have it plugged in properly. I suppose, lacking more detail, that "nuthing" means no voltage at all to the torch, not even sensing voltage. Normally these welders send slight current to the torch once you depress the pedal to sense when you lift the torch from the workpiece and then the arc is created. What settings are you using on the XMT (Lift-arc TIG or Scratch start, amps?), what are you trying to weld (type of metal, thickness) , what polarity (torch DCEP or DCEN), do you have a good ground clamp connection to the work, do you have argon supplied to the torch?

      Dern it, beat me to the post.
      Last edited by Dmaxer; 09-11-2009, 11:44 PM. Reason: last sentence

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      • #4
        Owner's manual for XMT 300 CC/CV

        http://www.millerwelds.com/om/o2205l_mil.pdf

        I'll take a guess that you have one or more of the toggle switches in the wrong positions and that's why there's no weld power. Pages 9-12 of the manual explain how to hook it up and set the controls to weld with it. Correct position of the switches depends on whether you're using it with a pedal or not. The controls are a little different than my 304 I described earlier.

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        • #5
          Xmt

          The early models of the XMT are not connected to single phase as you would expect. Miller used red as a hot wire. Later, red was taped and not connected just as normal convention would dictate - so make sure your machine is late enough to follow the 'black/white L1/L2' that we would all expect - green always ground, of course. This is probably not your problem since I believe you said the machine 'powers up' which I took to mean the fan comes on. weldersales

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          • #6
            sorry for the lac of info. The mechine is 220v and i followed the miller manual that says tig tourch neg, gound cable positive. set the arc dial to zero.

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            • #7
              If your current is set at zero, it won't have any weld output. Turn it up. One amp per one thousandth inch of material thickness is a good place to start.

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              • #8
                First off, an XMT 300 is unlike any 304. As techs we are afraid of starting them as the screwed up ones go off like fireworks. So we like to start them on a 10 amp or less circuit.

                So put your 3 top left switches to the left and scratch start the unit. As said your remote will only go as high as the local control.

                You failed to mention if you had CC stick control. If you have no output, and the unit does switch on without the fireworks, then the right side vertical board near the fan area likely has a bad relay.

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                • #9
                  Is the ground hooked up on the inside of the machine? Ihave had problems with my plasma doing the same thing and the ground wire comes loose inside the machine. I just hook it back up and all is good again.

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                  • #10
                    XMT 300 cc/cv Troubleshooting

                    Serial Number KD395855

                    welder sales mentioned the following and I am trying to figure out if my welder may use the red wire for single phase hookup. How would I descern if it was an "early model". My welder does works but misbehaves some. I can provide descriptions of the symptoms but want to clarify weldersales details first. The machine does power up and welds but the LED display does not provide accurate details and once in a while the welder will trip the breaker.

                    The early models of the XMT are not connected to single phase as you would expect. Miller used red as a hot wire. Later, red was taped and not connected just as normal convention would dictate - so make sure your machine is late enough to follow the 'black/white L1/L2' that we would all expect - green always ground, of course. This is probably not your problem since I believe you said the machine 'powers up' which I took to mean the fan comes on. weldersales
                    Last edited by jimybud; 09-08-2013, 07:28 AM.

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