Migatronic automig 140 mono

  1. Hendrik New Member

    Messages:
    6
    Location:
    Holland Zuid-Holland
    Hi,
    The other day i bought this broke welding machine for its binzel torch. But maybe its worth saving.
    I removed the torch. When you turn it on the relay (contactor) clicks immediately one time. The feed motor does nothing, so does the gas solenoid. Does anyone know what could be wrong with the machine?

    In the inside of the machine there's more wrong. I've taken this picture where you can see the metal has molten. I've unbolted the connection. Is is advisible to just grind the surfaces a then connect them again?
    Regards, Hendrik
     
    • 20200418_141022.jpg
  2. eddie49 Member

    I think it has spent a long time in a damp environment, possibly salt-water too. The thick copper wire has corroded at the steel connections to the rectifier. The enamel insulation of the winding on the inductor above has also been damaged. The initial on/off click of the contactor probably means that joints and tracks on the control PCB have corroded too.
    It is normally rare for me to say this, but: "No".
     
  3. Rig Pig

    Rig Pig Member

    Messages:
    3,755
    Location:
    Narrwich! U.K.
    I'd say it's worth a look, those melted thick wires look like aluminium, maybe there was corrosion on the terminal that overheated the joint.
     
    johnser likes this.
  4. Hendrik New Member

    Messages:
    6
    Location:
    Holland Zuid-Holland
    Hi,
    I've cleaned and connected the thick aluminium wire to the rectifier.
    I've found out that the pcb is a 180 mono model (number on the pcb). When you unplug the pcb the contactor releases immediately. When you pull the lever of the welding pistol the component R68-J 9W-A1 on the pcb overheats and starts smoking. The wire feed motor and the gas solenoid don't work. Does anyone have a clue what is wrong with the pcb?
    Regards, Hendrik
     
  5. stanbester Member

    Messages:
    71
    Location:
    United Kingdom West Yorkshire Halifax
    It is worth saving.
     
    johnser likes this.
  6. johnser

    johnser Member

    Messages:
    2,003
    Location:
    North Cornwall
    Yup, worth it I reckon.

    Even if you end up just using the component parts; wirefeed motor, contactor, transformers etc and wiring them to a new, different if needs be, control circuit, would be worth it IMO.
     
  7. eddie49 Member

    I think that the Migatronic 180 Control PCB circuit diagram in this old thread may apply to your machine:
    https://www.mig-welding.co.uk/forum/threads/migatronic-180-difficulties.50005/
    There is a resistor on that diagram marked R68, but that is not the component number, it is the value - i.e. 68 Ohms.
    Anyway, it is in the Collector circuit of power transistor T3, which is a BDV64B, 10 Amp 100v PNP. This transistor drives the wirefeed motor, which you said is not working. I would suggest pulling one wire off the motor, and check if the resistor no longer overheats. Then reconnect the wire briefly via an Ammeter. I would not expect the motor to need more than 2 Amps ( if it is 24v, 2 Amps = a 48 Watt motor ). If it is drawing too much current that may be because it is stalled. Try disconnecting the motor fully and running it from a 12v battery. It should turn slowly. The motor may be faulty, or it, or the gearbox, may be jammed, for example with stale hardened grease.
     
    stanbester likes this.
  8. Hendrik New Member

    Messages:
    6
    Location:
    Holland Zuid-Holland
    Hi eddie49,
    Thank you for the link to the circuit diagram and your suggestions to my question. I’ll try them out and report back the results.
    Regards, Hendrik
     
  9. Wedg1e

    Wedg1e They call me Mr. Bodge-angles

    Messages:
    6,575
    Location:
    Teesside, England
    R68 would be 0.68 Ohms, not 68 Ohms.
     
    eddie49 likes this.
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