Announcement

Collapse
No announcement yet.

120V Not Working After Unit Warms Up

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • 120V Not Working After Unit Warms Up

    I have a Bobcat 250 and both of my 120v receptacles will quit working after using them for about an hour. If I let it sit overnight, I can use it for another hour and then they quit working again. I have replaced both 20 breakers and it still does the same thing. Any suggestions on what to try next?

    Thanks

  • #2
    Sounds like something is heating up and opening or going into a high resistance state. Are you trained and comfortable probing around in hot circuits that can kill you? Going to have to check inside with the machine running while it's hot. If you are not comfortable with that, please find someone who is and will try to help. Please post your serial number.
    Last edited by Aeronca41; 09-18-2017, 07:18 PM. Reason: Fix autocorrect word replacement

    Comment


    • #3
      I'm an electrician, but not a welder repairman. That's WEIRD!!! Looking forward to seeing the resolution on this one.

      Comment


      • #4
        Wierd indeed. I remember one back in the 1960s -- trying to fix a Tektronix oscilloscope everyone had given up on. Triggering got flaky after runnng for 2-3 hours. Took me months of on again off again spare time to find the problem. It used vacuum tubes, and I found when it got warm the filament voltage in the trigger amp tube was dropping from 6.3 to a little over 5 volts. Found a 1/16 square metal bus bar so close to a filament pin on the tube socket that when it expanded from heat it was just barely touching and generating a "high resistance short" ( if there is such a thing) to ground. Bent the bus bar about a sixteenth of an inch and all was well. Hope this one isn't quite that wierd!

        Comment


        • #5
          In automotive and industrial equipment it isn't that unusual. A component expands from heat and loses contact inside.
          My stupid Bobcat skid steer has this thing going on if the sun shines too long on the black roof, the ignition switch module fails and shuts the machine down. I unplug it, bring it inside into the AC for a bit, take it out and plug it in and WHAMO....she runs fine until it gets hot again.
          It's only $800 bucks.

          www.facebook.com/outbackaluminumwelding
          Miller Dynasty 700...OH YEA BABY!!
          MM 350P...PULSE SPRAYIN' MONSTER
          Miller Dynasty 280 with AC independent expansion card
          Miller Dynasty 200 DX "Blue Lightning"

          Miller Bobcat 225 NT (what I began my present Biz with!)
          Miller 30-A Spoolgun
          Miller WC-115-A
          Miller Spectrum 300
          Miller 225 Thunderbolt (my first machine bought new 1980)
          Miller Digital Elite Titanium 9400

          Comment


          • #6
            Originally posted by FusionKing View Post
            In automotive and industrial equipment it isn't that unusual. A component expands from heat and loses contact inside.
            My stupid Bobcat skid steer has this thing going on if the sun shines too long on the black roof, the ignition switch module fails and shuts the machine down. I unplug it, bring it inside into the AC for a bit, take it out and plug it in and WHAMO....she runs fine until it gets hot again.
            It's only $800 bucks.
            Wow! At 800 bucks for a new one it sounds like you found the right answer. Any room to mount a fan to blow on it?

            Comment


            • #7
              Maybe it just needs its union break every four hours.

              Comment


              • #8
                When cold and engine off... What is your resistance reading at receptacle between plugs and either to frame?
                When hot and failing and engine off... What is your resistance reading at receptacle between plugs and either to frame?
                Same on 240 plug. The double pole breaker is in the circuit and feeds the other two single breakers.

                Cold and Hot readings should be the same..
                Last edited by Popscott; 09-20-2017, 08:55 AM.

                Comment


                • #9
                  Just Curious... have you flipped the double breaker on and off to see if it effects the situation when it quits?

                  Comment


                  • #10
                    Good question !

                    Comment


                    • #11
                      Originally posted by Aeronca41 View Post
                      Wow! At 800 bucks for a new one it sounds like you found the right answer. Any room to mount a fan to blow on it?
                      For now we simply keep it indoors all the time, in the AC.

                      www.facebook.com/outbackaluminumwelding
                      Miller Dynasty 700...OH YEA BABY!!
                      MM 350P...PULSE SPRAYIN' MONSTER
                      Miller Dynasty 280 with AC independent expansion card
                      Miller Dynasty 200 DX "Blue Lightning"

                      Miller Bobcat 225 NT (what I began my present Biz with!)
                      Miller 30-A Spoolgun
                      Miller WC-115-A
                      Miller Spectrum 300
                      Miller 225 Thunderbolt (my first machine bought new 1980)
                      Miller Digital Elite Titanium 9400

                      Comment


                      • #12
                        Paint that roof white

                        Comment


                        • #13
                          Originally posted by shootist2 View Post
                          Paint that roof white
                          Glue an inch of silver-backed Styrofoam on it!

                          Comment

                          Working...
                          X