Migatronic 325 compact

  1. Topi New Member

    Messages:
    14
    Location:
    Finland
    Hi! I have a problem with wire feeding. Changing the position of wire controller or any of controls wire keeps going with full speed all the time. No matter is wire freely or in action.
     
  2. eddie49 Member

    Hello, and welcome to the Forum !
    The problem sounds like a failed component on the Control PCB, in the motor speed controller. Could be a power transistor that has gone short-circuit. If you have electronic skills, or know someone that does, start by checking any large transistors on that board - ones with heatsinks - for collector-emitter shorts. If not, let us see a photo of that PCB, and also any precise model numbers for your MIG and on the PCB, to try to find a Manual and a circuit diagram.
     
  3. Topi New Member

    Messages:
    14
    Location:
    Finland
    Thank you! I will load couple of photos.
     
  4. Topi New Member

    Messages:
    14
    Location:
    Finland
    Pics from Electronic
     
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    • IMG_20200227_060256.jpg
    • IMG_20200227_060056.jpg
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  5. eddie49 Member

    There are no parts in the above photos that are large enough to drive a wirefeed motor. We're looking for power transistors:
    2N3055.png
    or
    TO-220.jpg
    that are mounted on heatsinks. If necessary, trace the wires from the wirefeed motor to locate these components.
     
  6. Topi New Member

    Messages:
    14
    Location:
    Finland
    There is one transistor like in last picture and its mounted in aluminium heatsink plate with very thin plastic plate separating them.
     
  7. Topi New Member

    Messages:
    14
    Location:
    Finland
    There it is
     
    • IMG_20200227_091233.jpg
  8. Topi New Member

    Messages:
    14
    Location:
    Finland
    And a smaller one bolted in aluminium, this transistor is covered with plastic all the way.
     
  9. Topi New Member

    Messages:
    14
    Location:
    Finland
    Smaller
     
    • IMG_20200227_091646.jpg
  10. Topi New Member

    Messages:
    14
    Location:
    Finland
    Here it is, might it be the right one?
     
    • IMG_20200227_111248.jpg
  11. Topi New Member

    Messages:
    14
    Location:
    Finland
    Smaller one
     
    • IMG_20200227_111756.jpg
  12. eddie49 Member

    The Siemens TXD10K40 in your post #10 is a 400v 8Amp Triac. It is a switching device for AC. It is just possible that it could be the motor speed controller, but only if the wirefeed motor is an AC motor, which would be unusual. Mostly these motors are DC, but I'm not familiar with large 300 Amp MIG welders.
    If that Triac is short-circuit, the pins A1 to A2, and vice-versa, would be a low resistance all the time. On a good Triac, those pins only conduct when there is a trigger pulse on the gate pin G.
    On the smaller power transistor - post #11 - I can't see the part number.
    What is the exact model number of your MIG, and are there any numbers on the PCBs, to try to find a Manual and a circuit diagram?
    Without a diagram, can you trace the wires from the motor to the PCBs and components?
    Please check the voltage across the motor when it is running continuously, to confirm if it is DC or AC.
     
  13. Topi New Member

    Messages:
    14
    Location:
    Finland
    ill get to migatronic today and take photo of serial number of machine and the control unit. I have unit here now in my home ill take the picture now. and have some measure with multimeter. Thanks you a lot Eddie you are super! I have founded some wiring diagrams of migatronic 325 compact from depths of internet but they are pretty poor quality. And by the way there was a random few seconds period when machine starts feeding slower when feeding controller stands low position.. Then full a head again. I remember now.
     
  14. Topi New Member

    Messages:
    14
    Location:
    Finland
    Box nro. If there is some use?
     
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    • IMG_20200228_063743.jpg
  15. Topi New Member

    Messages:
    14
    Location:
    Finland
    Here is some poor picture of wiring
     
    • Screenshot_20200228_071141_com.android.gallery3d.jpg
  16. Topi New Member

    Messages:
    14
    Location:
    Finland
    wire feed motor is dc. Its rolls about 18volts all the time
     
    • IMG_20200228_141145.jpg
    • IMG_20200228_141206.jpg
  17. Topi New Member

    Messages:
    14
    Location:
    Finland
    Just weld 7mm plates with 1mm esab wire and bernard torch and boy how good it burns! But damn with that wire feed..how frustrating
     
  18. eddie49 Member

    I am pleased that the MIG does weld very well !
    In your post #11 there is a small plastic transistor, bolted with a mica washer under it. It might be a power transistor. Could you remove the bolt and take a photo so we can see the markings?
    One way to eliminate the problem would be to replace the motor speed controller with a new pulse-width-modulated ( PWM ) motor controller:
    https://www.ebay.co.uk/itm/DC-6V-28...gulator-Controller-Switch-Module/163546933627
    You could feed that new controller with 24v DC taken from the original PCB, or even add a stabilised 24v 3A power supply:
    https://www.ebay.co.uk/itm/3V-5V-9V...-Supply-Driver-Adapter-LED-Strip/254289649333
     
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