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Trouble with High Frequency

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  • Trouble with High Frequency

    Hi guys,
    I am new to this forum and I am hoping someone can point me in the right direction to get rid of a gremlin I have in our welding shop.
    I am a maintenance technician/electrician at a welding school and I have suddenly had several welders go down, one on Saturday and three today not including a Lincoln welder that also went down Saturday.
    My problem is that the High Freq. mode has gone out and will not strike an arc. I had another Miller become erratic on Friday but I adjusted the spark gaps and I think that took care of that one.
    I really could use a suggestion or two to figure this one out. These are all Synchrowave 250 DX.
    Thanks in advance for any help.
    Last edited by TwsSparky; 05-20-2013, 01:10 PM. Reason: Forgot to add type of machine

  • #2
    Ahhh, serial #'s determine machine age, and wiring diagram, there are many


    • #3

      Serial number on one is LK00009L

      Otherwise they are each identical.


      • #4

        I called Miller yesterday and one of the technicians there e-mailed me an article from a Newsletter for Miller Service Agencies which has got me tracking again but as of yet have not found the problem.


        • #5
          Solution to two of the welders

          After spending almost two days on the one welder I decided to check things on the other two that were giving no High Freq. and found that one needed the spark gap adjusted, and the other had an open 50 ohm WW resister. Once that was replaced it started working like a new welder.
          I am still stumped as far as the first one.


          • #6
            First check your preflow setting if the welder has one. You only get gas until the preflow time times out. Second. look at the machine diagram and find the HF transformer primary. Should read around 110 volts ac. When HF is called for.
            Check 110 circuit breaker on the front of the welder. If it was tripped, no HF.
            If you have 110 volts, then you might have a problem with the HF cap, spark gap assembly or the HF transformer secondary. Secondary voltage is very high and will kill most meters, around 3000 volts, the cap can be measured, and the points checked for shorts.
            Have fun and be careful.
            Glenn 300 amp stick
            Millermatic 35
            L-tec plasma


            • #7
              Thank you for the reply. It has been very busy here thus the delay in response. I do have 110v at the primary and I was aware of the detriment to meters on the secondary, but thank you for the reminder anyway. Things are beginning to slow down a bit here, so I should soon be able to get back to that machine and start working on it again. You may be right about a bad cap. Thanks again.


              • #8
                Found it

                Was just reviewing posts and decided to add in the solution I found for those who might run into the same situation. I disconnected one leg of the C1 cap and applied power. It gave me a mushy sounding high frequency which indicates C1 is bad. Once I replaced C1 I was back in business. Thanks for the suggestions guys.