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Miller cst 250

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  • Miller cst 250

    My welder has a very weak arc on both stick and tig . This is an older miller cst 250 the blue light does not flash and it turns on and off normal.
    There is 30 volts DC at the output on the tig setting and 60 Volts DC at the output on the stick setting. I have removed the case and there is a little dust but no smoked parts. Everything seems tight that should be . I have read about similar problems but no answers to the fix . I suspect it is the PC1 board but would like to hear what you guys think thanks

  • #2
    What you want to do is meter the pos and neg at the machine while you strike an arc. (In stick). If the machine remains at an ocv of 60, the problem is with your cables, if it drops to zero, the problem is with the machine. If I had to guess, the problem is with the line switching, and it's stuck in a higher voltage. This is the autolink boards. Very pricey.


    • #3
      Thanks Cruizer I will try that . I don't think its the cables its probably the Pricey board


      • #4
        If your welder has a window on the side with either 230 or 460 displayed in it. yours is a manual link machine.
        You have to take the cover off and switch the link pcb around to change line voltage.
        See if you have 10vdc at pins C and D on the remote plug. Panel control has to be turned all the way up.
        These units are limited to around 200 amps on 230 volts single phase, Or if you have a bad line and the line current is to high.
        Blue light will flash two times repeatedly.
        Your problem could be caused by any of the 4 pcbs in the welder. With out testing to find out which one is weak, you could be wasting money
        replacing pcbs that are good. Hope it is just a bad connection in the weld leads.
        Glenn 300 amp stick
        Millermatic 35
        L-tec plasma