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Millermatic 350 troubleshoot

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  • Millermatic 350 troubleshoot

    I got a Millermatic 350 about 9 months ago. This rig was given to me because it was supposed that it was 460v input only. I happened to look at the plate on the back of it the other day and it also says single phase 230v. I took the panel off the right side of the machine unplugged a little plug moved the power bar to the correct voltage, plugged the little plug back up just as the diagram inside the cover shows. Now I don't really know how to wire in my wire for input voltage to make this thing work. I know the machine works because I welded with it before it was given to me at Ram-Fab Inc. Any help here would be awesome!

  • #2
    Click image for larger version

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    This is my try at it, and what I am looking at.


    • #3
      Unsure what plug your talking about, all there is to change voltages on a mm350 is the slider on the right side board panel.

      On single phase you drop the red primary.


      • #4

        Please look at the attached pic and wire it up this way for single phase.

        From your picture, swap the red and white wires.

        Attached Files
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        Victor O/A
        Premier Power Welder for my trail junk.


        • #5
          Put your white cord wire on the middle connection. The right one is for the red cord wire cruzer talked about.
          Do not move the little red or white wires. If put in the wrong place, resisters on the other side of the welder will bunt up. Just move your white cord wire over to the middle connection. Your cord wires must connect to the contactor terminals with the small red and white wires. The small wires go up to the line switch and then to the power pcb through the soft precharge resistors and then into the power pcb. When the inverter caps charge up then the contactor pulls in and you are ready to weld.
          Last edited by ccawgc; 06-05-2012, 01:38 PM.
          Glenn 300 amp stick
          Millermatic 35
          L-tec plasma


          • #6
            Thank you guys tremendously! I have been in this business for 14 years. Never known much about the technical aspect of these things. I have just burnt rods or wire. TIG, MIG, stick and subarc. Every metal imaginable, inconel, monel, duplex, hastalloy, AL6XN, alloy 20, titanium, all grades of chrome and stainless and of course carbon steel. Now I'm in a position where I work I may have to do a little work on some of these machines. We mostly have XMT 304s at work now and one new pipeworx. Anyway I can't thank you guys enough for your help.


            • #7
              Ok guys, I guess I spoke too soon. I hooked my machine like you guys said, and voila! I have power. BUT! The contactor where the power inputs is BUZZING like crazy. Surely this is not normal. Is this a sign that that contactor/coil is bad? Can I get another one at an electrical supply house?


              • #8
                Basically its a sign that there is crap on the mating surfaces of the shunts.

                Unplug the unit.

                Unfasten the contactor from its mounts and flip it over to the base. Take the screws out, and remembering how it goes back together, remove and clean the mating surfaces of the shunts with emery or scotchbrite. Reassemble, and it should be ok.

                Now if you remove ANY wires off that contactor, make sure they go back in exactly the same place, ie, the small auxillary wires, if you put one of them in the wrong place, the unit will go KABOOM


                • #9
                  Thanks a million! Will do asap!