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Bobcat 250 blowing f6 fuse

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  • Bobcat 250 blowing f6 fuse

    upon starting it blows the f6 fuse. Checked D4 and it checked good. Checked the rectifiers and found one bad and replaced. Still blowing f6 on start up

  • #2
    Does it blow while cranking or after it starts?

    If while cranking, disconnect the plug from the ignition switch and check for continuity between the START terminal and switch body with the switch turned to START. Continuity under this condition indicates a bad ignition switch.

    If F6 doesn't blow in the above test, reconnect ignition switch and disconnect the "start" signal wire from the starter solenoid and see if F6 still blows when the ignition switch is turned to START. If it still blows, disconnect the anti-dieseling solenoid on the carb and try again. If it still blows, disconnect the red lead feeding the oil pressure switch (COMMON terminal) and try again. If it still blows, disconnect flashing diode D4 and try again.

    You might want to rig up a circuit breaker to save on fuses for the above tests that can be conducted in any order you prefer.
    MM200 w/spot controller and Spoolmatic 1
    Syncrowave 180 SD
    Bobcat 225G Plus LPG/NG w/14-pin*
    *Homemade Suitcase Wire Feeder
    *HF-251D-1
    *WC-1S & Spoolmatic 1
    PakMaster 100XL
    Marquette "Star Jet" 21-110
    http://www.millerwelds.com/images/sm...rolleyes.png?2

    Comment


    • #3
      It blows right after it starts. Will try your test and get back to you. Thanks for the help

      Comment


      • #4
        Look inside the unit on the bulkhead and/or backside of control panel for a small (3/4" wide x 2" long) SN tag. Could really use the full SN of the unit.

        I take it the unit dies as soon as F6 blows?

        I suggest you recheck the two bridge rectifiers and D4 with it disconnected from the circuit.
        Last edited by duaneb55; 02-23-2017, 07:34 AM.
        MM200 w/spot controller and Spoolmatic 1
        Syncrowave 180 SD
        Bobcat 225G Plus LPG/NG w/14-pin*
        *Homemade Suitcase Wire Feeder
        *HF-251D-1
        *WC-1S & Spoolmatic 1
        PakMaster 100XL
        Marquette "Star Jet" 21-110
        http://www.millerwelds.com/images/sm...rolleyes.png?2

        Comment


        • #5
          San- LB158213. Yes the machine dies as soon as f6 blows. Will recheck rectifiers and D4

          Comment


          • #6
            When checking the bridge rectifiers and D4 to make sure they are disconnected to isolate them false readings. D4 would have to be shorted closed (continuity both ways) to back feed exciter voltage into the battery circuit to blow F6. If F6 still blows with D4 disconnected then the problem is on the battery/ignition side of things and you will have to employ the process of elimination by disconnecting/testing circuits.for shorts to ground.

            For example, disconnect both leads from the oil pressure switch and connect them together. If it starts, runs and doesn't blow F6 then the OP switch is shorted.
            MM200 w/spot controller and Spoolmatic 1
            Syncrowave 180 SD
            Bobcat 225G Plus LPG/NG w/14-pin*
            *Homemade Suitcase Wire Feeder
            *HF-251D-1
            *WC-1S & Spoolmatic 1
            PakMaster 100XL
            Marquette "Star Jet" 21-110
            http://www.millerwelds.com/images/sm...rolleyes.png?2

            Comment


            • #7
              Everything checked out good. I unplugged the voltage regulator on the motor and it will crank and run but as soon as it's plugged back in it blows the f6 again. It also will not idle down anymore

              Comment


              • #8
                OK. So the battery charging voltage regulator is to blame and sounds as if it's trying to pump AC voltage into the battery circuit which is blowing the fuse on the (-) swing of the AC output from the engine stator.

                It may also have damaged the idler module resulting in your no low idle condition. I'd replace the regulator first and retest.
                MM200 w/spot controller and Spoolmatic 1
                Syncrowave 180 SD
                Bobcat 225G Plus LPG/NG w/14-pin*
                *Homemade Suitcase Wire Feeder
                *HF-251D-1
                *WC-1S & Spoolmatic 1
                PakMaster 100XL
                Marquette "Star Jet" 21-110
                http://www.millerwelds.com/images/sm...rolleyes.png?2

                Comment


                • #9
                  Ok thanks for the help

                  Comment


                  • #10
                    Could the voltage regulator also cause the machine to have no power output on the 110 and 240 plug? Currently waiting on regulator to get here

                    Comment


                    • #11
                      Ok new voltage regulator installed and it still blew the f6. But the idle control is working and have all power at plugs and welding leads

                      Comment


                      • #12
                        ???

                        What size fuse are you using for F6? Should be 30A.
                        MM200 w/spot controller and Spoolmatic 1
                        Syncrowave 180 SD
                        Bobcat 225G Plus LPG/NG w/14-pin*
                        *Homemade Suitcase Wire Feeder
                        *HF-251D-1
                        *WC-1S & Spoolmatic 1
                        PakMaster 100XL
                        Marquette "Star Jet" 21-110
                        http://www.millerwelds.com/images/sm...rolleyes.png?2

                        Comment


                        • #13
                          Yes sir it is a 30A. As long as I leave the regulator disconnected everything works as it should

                          Comment


                          • #14
                            You don't have the battery hooked up backwards do you?
                            MM200 w/spot controller and Spoolmatic 1
                            Syncrowave 180 SD
                            Bobcat 225G Plus LPG/NG w/14-pin*
                            *Homemade Suitcase Wire Feeder
                            *HF-251D-1
                            *WC-1S & Spoolmatic 1
                            PakMaster 100XL
                            Marquette "Star Jet" 21-110
                            http://www.millerwelds.com/images/sm...rolleyes.png?2

                            Comment


                            • #15
                              OK. Long shot.

                              Unplug the voltage regulator rectifier and check resistance between the two AC input (outer) leads. Resistance should be between .064 and .2 ohms.

                              Then check from each AC lead and ground. Both should be open (no continuity). If either has continuity to ground, the stator is shorted to ground.
                              MM200 w/spot controller and Spoolmatic 1
                              Syncrowave 180 SD
                              Bobcat 225G Plus LPG/NG w/14-pin*
                              *Homemade Suitcase Wire Feeder
                              *HF-251D-1
                              *WC-1S & Spoolmatic 1
                              PakMaster 100XL
                              Marquette "Star Jet" 21-110
                              http://www.millerwelds.com/images/sm...rolleyes.png?2

                              Comment

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