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Auxiliary power output?

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  • Auxiliary power output?

    1996 Miller Bobcat 225G Plus - Serial # KG052667. Should I have a full 120 volts at the aux power receptacles when the engine is at fast idle?

    At slow idle I have about 30 A/C volts and at high idle I have about 90 A/C volts. Both idles are set correctly (per rpm - I can't measure freq.) and the fine tune control is at "10". Adding an aux A/C load does not change the voltage output. My concern is, if I don't have full volts at aux power, I won't have full volts in the welding leads?

    If those voltages are low (and I suspect they are), what would cause this? And how do I test/fix it?

    Any help is greatly appreciated.

  • #2
    Bad power board, or get a meter that reads frequency. Worthless to ask questions without that tid bit of information.


    • #3
      Thanks Cruizer. I bought a frequency meter. I raised engine rpm until I got 43 Hz at slow idle and 62 Hz at high idle (as you have recommended in the past). Volts came up to about 75 (slow idle) and 122 (high idle).

      My concern now is that I am over-revving the engine and that will lead to pre-mature engine failure. I believe I am at about 3520 rpm slow idle and 4400 rpm high idle.

      Any other thoughts, advice, or troubleshooting tips?



      • #4
        Auxiliary power output?

        Are you sure your tach is accurate?


        • #5
          Yep, your tack gage is out to lunch!


          • #6
            Comparing your windings / rotor to your frequency, your high idle is actually around the 3750RPM
            mark, which is just about correct,

            Your low idle rpm is around the 2360 RPM mark which would be acurate


            • #7
              Thanks cruizer and Manisoba. My tachomter is questionable. It's an old tach that I have had for a long time. That may be the issue. I'll run her like she is for now. Again, thanks for all the help/advice.


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