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  • Bobcat 225nt

    I have a Bobcat 225nt with 80 hours on it. Sat out in a shed for years. Motor runs good, but when I tried to run a grinder only one plug worked, but very slowly. Welder just makes scratch marks, then the grinder worked a little better on both outlets, then nothing at all. I noticed sparks at the brushes when it was barely generating, but nothing there "now" also. Pulled the brush pack off and brushes work as they should and look new. Any help on tracing the cause wold be appreciated. Thanks, Pat

  • #2
    Just going from memory on my Bobcat as I had a similar problem a while back;
    First thing I would check is your Idle (2200) and Run ( 3700) RPM's..........you'll need a meter that reads Hertz at 60 cycles and you'll have to look at the specs to get the correct hertz value that corresponds with RPM ...........to low of RPM your grinder see's low voltage.......to high and it will burn it out....also the fine adjustment knob needs to be set at 10....Oh and there is a solenoid that has to work properly that engages the high rpm.......and adjustments there to set engine speed.........take a look at the manual.
    Last edited by tarry99; 03-18-2021, 04:12 PM.

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    • #3
      I'll see If I can locate a meter like that, thanks !

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      • #4
        Here's a link to an older post on the same machine and has the hertz value mentioned that you need:https://forum.millerwelds.com/forum/...-bobcat-225-nt

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        • #5
          If you do not weld or Aux. output measuring hertz is not possible. Your problem is most likely in excitation circuit. Check the plug & RC4 on the center panel this is the connection from the motor to the generator clean it and check if you have output if not covers come off. check all fuses you will need a volt OHM meter.to test SR2 & D4 Not sure if you have the knowledge to test these components but this will be a good start.

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          • #6
            Is you Voltage /amp knob turned up to 10?

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            • #7
              Yes, voltage set at 10. I'll do the tests above and see what happens. Can I install a rpm meter permanently and a hertz meter if so how ? Thanks guys !!!

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              • #8
                RPM & Hertz is not anything you need to monitor continually......only need to check if you have performance issues with generator or welder....to check, put the two prongs from the meter into the 120v receptacle on the face of the welder panel...set the rpm at the throttle solenoid and go to work..

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                • #9
                  To read hertz get a kill a watt meter. Home depot has them or online. https://www.homedepot.com/p/Kill-A-W...4400/202196386

                  hertz must 62/62.5, set rpm to what ever it takes to get the hertz correct.
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                  • #10
                    Is D4 the diode in the wire harness just after the connector, generator side, and soldered between to wires ? Thanks

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                    • #11
                      Originally posted by modelaawelder View Post
                      Is D4 the diode in the wire harness just after the connector, generator side, and soldered between to wires ? Thanks
                      No. That's D8. It's only used in the start circuit. D4 is on the panel with the fuse and 4 way rectifier

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