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Wire won’t stop feeding

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  • Wire won’t stop feeding

    Hi group, I am new to this site and looking for help. The pictures I posted are a welder I just bought. I was trying it out and the wire continues to feed without the trigger pulled in. I had to shut machine off to stop the wire. When I turn machine on the wire starts to feed out again. I unplugged the Torch trigger from the machine and it still feeds out. What should I look at or change first? Any help would be appreciated thanks in advance.

  • #2
    One of my mig welders had the same problem at one time, I opened up the torch end and cleaned the contacts on the trigger and maybe lubricated the trigger switch, fixed the issue. It has been so long ago I can't recall but I know the problem was with the switch and I did not have to purchase anything to fix the problem.


    • #3
      What happens if you unplug the cannon plug for the control circuit to the gun from the machine when it's spitting wire?

      Got a model and serial number for the machine so the wiring diagram can be accessed on Miller's site?


      • #4
        The serial number on the front of machine doesn’t come up on there website serial# JA371564. When the cannon plug is unplugged wire still comes out


        • #5
          Shawn, this should be the manual for your machine. It will also tell you how to remove the gun assembly.


          • #6
            You know what I'd do? I'd do two thinks actually. First would be to open it up like a gutted fish after unplugging it. Yup, well past warrenty what can a good look do for harm? Then I'd call Miller Tech Support.


            • #8
              Your problem is most likely stuck contacts on CR1, or something causing it to stay energized when it shouldn't. It is also possible you have a shorted transistor on the wire feed motor control board, or some other board problem, but let's look at the most obvious (and cheapest!) first. Are you trained and safe to work on hot circuits that will readily kill you if not respected? If not, please find someone qualified to give you a hand. No machine is worth fixing if you get hurt or killed in the process.

              I will be somewhat detailed in case you are not familiar with electrical troubleshooting, or to help others who may look at this some other time. Please don't think I'm talking down to you if you already know most of this stuff. Or, If something here is not clear and you need more detail, just ask.

              If you look at the diagram below (first pic), you will find CR1's coil in the upper left corner. (red circle). It's just an electromagnet that pulls the contacts when energized. Notice just above and to the right a 4-pin connector RC2 with a couple of pins jumpered together. This is the plug on the front of the welder where you plug in the MIG gun control cable. When you pull the trigger on the gun, pins 1 and 2 get connected together, energize CR1's coil, and move its contacts. Since the wire feed still runs when you unplug the gun, it is possible some wires are shorted together inside the welder making it think the trigger is pulled, but I think that's less likely than a bad relay (CR1). I have tagged with a large red arrow the contact pair that I will guess is stuck closed on CR1--those are the ones that start the drive motor. That same relay, by the way, also turns on relay "W" just below the left set of contacts for CR1. W, in turn, turns on the weld current to the gun. So, if all is working correctly, pull the trigger---CR1 energizes---starts wire feed motor---energizes W to turn on output power---sparks!!

              You can see if CR1 is working properly. Unplug and open up the welder, locate CR1 from the 2nd and 3rd photos below. Take a look at the two pairs of contacts on CR1. Both moveable contacts should be "away from" the coil, making contact with the furthest-from-the-coil stationary contacts. I suspect you will find one is stuck to the contact closest to the coil. You can further check it by applying power and working the gun trigger. FIRST, remove the tension from the drive rollers so you are not spewing wire around with a bunch of hot circuits exposed! Loose wires have a way of finding hot circuits, and the outcome is seldom pretty. Then, power up, pull the trigger on the gun and watch the contacts to ensure they both move; if one is stuck, it will stay as it is. If it is a bad relay, you can try, or take the old one to your local electrical supplier and they should be able to match it up. It has a 24 volt AC coil.

              Let us know if this turns out to be the problem. If not, more detailed troubleshooting will be required--could be a shorted wire somewhere, or a problem with the PC board.

              Click image for larger version  Name:	Slide1.JPG Views:	0 Size:	45.3 KB ID:	597354Click image for larger version  Name:	Slide2.JPG Views:	0 Size:	41.1 KB ID:	597355Click image for larger version  Name:	Slide3.JPG Views:	0 Size:	42.2 KB ID:	597356
              Last edited by Aeronca41; 05-27-2019, 09:50 PM.


              • #9
                Thanks every one for you help And Aeronca41 that is one heck of explanation thank you.


                • #10
                  Wayne, you're a stud.


                  • #11
                    Thanks, Ryan. Finally back for a bit. Haven't had much time to help people out here. Been dealing with Mom's estate and what I can only describe as incredible inefficiency in retirement and old age!

                    Shawn, I'm anxious to see what you find in there. I have a bit of fear for a shorted component on the PC board, but always start with the simple and cheap stuff first.
                    Last edited by Aeronca41; 05-28-2019, 09:34 AM.


                    • #12
                      I followed your instructions and turned the machine on with cover off while pressing the trigger I noticed all contacts and coils work except the cube relay contacts they don’t move. I hope that isn’t a indication of a bad pc board. I have a cube relay on the way. I attached two pictures of the cube relay that I’m talking about, the contacts don’t move when I press the trigger of the gun. Click image for larger version

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ID:	597380Click image for larger version

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                      • #13
                        Pop the plastic cover off the cube relay and see if you can open the contacts with a utility knife blade.

                        If they ain't locked together you might be able to use an emory board and get a few thousand more operations out of the machine.


                        • #14
                          Shawn, if the Miller documentation is correct, and I'm not fully senile yet (a point which my late wife would say with a smile could be subject to some discussion.....) I think you have the wrong relay. That one is not moving because I think it is CR2, not CR1, and it's used with the spoolgun; will not move unless you plug in a spoolgun at the lower right of the front panel and pull its trigger. If the diagram in the book is correct, the relay you are looking for does not have a plastic cover, and is up and to the left from the one in your picture. The advice from Franz is right on--once you have the correct relay, his suggestion is absolutely the way to go before buying a new relay. I checked Miller4less, and CR1 is just shy of $150, which is just outta sight--should be able to get one at an electrical supply house for something around $25, I would guess. Franz's approach is how you generally approach bad relays first, and will cost you nothing but a few minutes of your time. It is interesting that the parts list in the manual describes CR1 as a 24 volt DC relay, but the schematic diagram clearly shows it receives only AC voltage to actuate it, so the parts list description is wrong.

                          HOWEVER, if you find the contacts on CR1 are both moving as they should, you either have a shorted wire somewhere, or the PC (057314) board is bad. Actually, that is not a disaster if you have someone with some electronics knowledge nearby--there are not that many components on that board, and they can almost all be tested with a good digital multimeter. A new board is available from Miller4less, but it's $384. But, before deciding it's a bad board, we should probably spend some troubleshooting time on the phone just to be positive. If you can afford to let this thing sit until fall/winter--when my mom's estate is settled and I have the new roof on my house--I could try and fix it for you....this one is pretty low-tech, and I can't imagine any part on there costing more than $20-$30, but I don't even have a test bench set up right now--sold off most of my 1960s-era test equipment some time ago--and spent the last 20 years or so caring for my disabled wife. I've only recently bought more current equipment since she passed away, but it's all still in boxes waiting for me to build up a new bench and equipment racks. (Actually, when I think about it, maybe I am senile, investing in test equipment at 70+ ......but that's another discussion.)

                          So, have a look at the relays and see if my guess on the "wrong relay" is correct. Still hoping it's not the board. What part of the country are you located in?
                          Last edited by Aeronca41; 05-29-2019, 06:36 AM.


                          • #15
                            I am just west of Cleveland Ohio. The contacts you are speaking of were opening and closing when trigger was pressed. Could they still be bad?