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Trouble shooting a Syncrowave 351

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  • Trouble shooting a Syncrowave 351

    Does anyone know what may cause my welder to have full amperage (heat) when the foot pedal is touched but not depressed when TIG welding?

  • #2
    Nope. Not a clue or a guess. But if it was my problem, I know what I'd do. And it's not what you've done.
    I'd post a serial number, I'd post a picture, and I'd post some back ground information on what you know, done and discovered in trying to solve the issue.

    You post a serial number because things change. One year to the next. What foot pedal are you using?
    A picture because it adds interest and clues into the condition of the equipment in question.
    Back ground because frankly, how long you've had it, what you've done with it, used it for, could matter.
    What you've done and discovered. Some one could ask you have you downloaded a manual and done any electrical testing?

    I have a garden to dig up. As I flip dirt I'm going to ponder a bit my response. But right now, don't think of it as harsh, think of it as direction to how I'd solve the problem if it was mine to solve.


    • #3
      From his thread on 9/20

      "I am having a problem with my Syncrowave 351 that I purchased new in 1995. Serial number KF849482. I began having intermittent problems with amperage. When pressing the pedal, I would get full amperage with just a touch when TIG welding. I changed the micro switch and the potentiometer in the pedal but that didn't seem to fix the problem right away. Eventually it starting working normally again but all of a sudden the problem has returned. When welding Aluminum square tube with a 1/8" wall, just touching the pedal will blow a 7/16" diameter hole in the metal. My local welding supply houses have no idea what the problem may be and can't even suggest anyone who is knowledgeable about these older machines. Can anyone help me ? It's been a great machine."

      found this old thread, not sure if it will help you though.
      Ed Conley
      Passport Plus w/Spool Gun
      Miller 125c Plasma 120v
      O/A set
      SO 2020 Bender
      You can call me Bacchus


      • #4
        Is your foot pedal either an RFCS-14 or -14HD? Either will work the same, but need to know if you have that or something else.
        Do you have a multimeter and know how to use it? Can give you a couple of things to check if so. I suspect, though, that the problem is with the Hall Effect device and it's associated circuitry inside the machine, and there are no diagrams for the circuit cards in the owner manual, so not much to be done in there after some basic wiring checks.


        • #5
          Thank you every one for your feed back. We have spent a lot of hours trying to find the problem and narrowed it down to the main board or the current control. The problem is intermittent and that is the frustrating part. We checked all connections and used a freezer spay and heat gun to eliminate any opens but the machine won't give up its secret and tell us what's wrong. It appears to be working okay now but time will tell if the problem returns. Serial number is KF849482


          • #6
            Very frustrating ! The problem has returned and I can't find anyone who can diagnose the problem and Miller is no help at all.


            • #7
              What happens when you turn down the amperage control on the front of the machine and use the pedal. Does it still send out max amperage?

              What about when you adjust the start amperage control? Any change?


              • #8
                This is embarrassing to write this comment. After months of intermittent problems with the welder and checking so many circuits, changing the torch and checking every thing inside the foot pedal, the welder finally gave up it's secret and had the "last laugh" . The power lead from the foot pedal had a frayed wire. When the foot pedal was moved to a different position, the wire would open and the reverse would be the wire closing. Depending on the position of the pedal, the high frequency would jump across the frayed section. With such a thick enclosed cable, one would never think to check it. It's kind of like when your car engine won't start, you start checking every thing except the fuel gauge. Thanks for everyone's help in trying to diagnose my problem.


                • #9
                  Glad you found it! Intermittents are a real pain.

                  It think my worst intermittent ever was on a multi-million dollar piece of equipment that had the customer very unhappy. Finally found if I would leave a scope probe on a certain point (scope didn't have to be attached, just the probe), it would work fine. Ran it that way until the weekend when we found the open capacitor that was allowing noise on a trigger line. What's really bad is when it's your car or truck!
                  Last edited by Aeronca41; 06-17-2020, 08:24 PM.