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mike 109444
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Motor braking not working
mike 109444
Member
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See Eddie's post #5
Pcb schematic automig 180 xe
Hi have someone got a pcb schematic for this welder
www.mig-welding.co.uk
Sorry i have no welder technical knowledge so burnback is to do with the top right knobs, will try fiddling with them tomorrow. Thanksburnback setting?
burnback setting?
Ok so that is the wire feed motor, will take tin cover off tomorrow and check around after checking burnback. Thanks
Removing the tin cover from the motor will expose the armature and brushes, but the braking is done by an electronic circuit on the printed circuit board. A power transistor is triggered to short the spinning motor, so that as it runs down it has to act as a generator feeding power into a short, which stops it.
Maybe the wire runs on because there is insufficient tension on the brake spring in the spindle for the MIG wire spool.
However, if the MIG wire not only feeds on but also remains live, this implies the contactor ( large heavy-duty relay, rear bottom left of the chassis ) is sticking on after release of the torch trigger. This may be due to magnetic welding/grinding dust jamming the mechanism. You could try blowing it clean with an airline. Failing that, it can probably be carefully dismantled for a thorough cleaning.
Maybe the wire runs on because there is insufficient tension on the brake spring in the spindle for the MIG wire spool.
However, if the MIG wire not only feeds on but also remains live, this implies the contactor ( large heavy-duty relay, rear bottom left of the chassis ) is sticking on after release of the torch trigger. This may be due to magnetic welding/grinding dust jamming the mechanism. You could try blowing it clean with an airline. Failing that, it can probably be carefully dismantled for a thorough cleaning.
Ok had a look under cover today, nothing looked amiss, will blow out tomorrow. How many wires should go to wire feed motor ? Also what is the knob under the cover in pic used for ? And knob on the front is loose on spindle, only 3 positions marked but there are actualy 10 clicks on the spindle, any idea which is off ?
The wirefeed motor is a permanent magnet 24v DC motor, so it has just two wires - plus and minus.
The 3-position front panel switch has three operating modes. The switch is supposed to have limits, but it may have been replaced by a new one with a greater range of rotation than originally required. You'll have to find the correct position for the control knob by checking against the three actual functions, which are:
The first position is for Continuous welding, with press trigger = On, release trigger = Off .
The second position is the same, except that press & release = latched on, press & release = off.
These two modes are known as "Two Touch" and "Four Touch" ( 2T / 4T ). The second mode ( 4T ) is useful for long runs of seam welding, where it is not necessary to keep holding the trigger depressed.
The third position is for Stitch Welding, where the machine will automatically stop and restart the welding process as the torch is moved, creating gaps in the weld bead which allow cooling. The stop/start time duration is controlled by the timer potentiometer(s).
The variable resistor on the back of the electronics box may be the Burnback control mentioned by daleyd in post #2.
This circuit allows the arc to continue for a short variable time after the wire has stopped feeding, which causes the wire to melt back inside the gas shroud, so there is no need to cut off excess wire before starting the next weld.
Does the MIG wire remain "live" for the time that it wrongly feeds an inch out, after you have let go of the torch trigger switch? ( i.e. you can arc with the tip of the wire ). If the wire feeds out but does not arc, there is a fault in the motor brake. If it feeds out and can arc, the contactor may be sticking "on" after the trigger switch is released. The contactor is the white component mounted on the chassis under the electronics box in your first photo.
Maybe there is just a brief spark, caused by the charge remaining in the smoothing capacitors. This voltage should be discharged by a bleed resistor across the capacitors. Your first photo in post #8 shows what looks like non-standard wiring for this resistor.
Circuit diagram for the PCB may be the one in post #16 here:
The 3-position front panel switch has three operating modes. The switch is supposed to have limits, but it may have been replaced by a new one with a greater range of rotation than originally required. You'll have to find the correct position for the control knob by checking against the three actual functions, which are:
The first position is for Continuous welding, with press trigger = On, release trigger = Off .
The second position is the same, except that press & release = latched on, press & release = off.
These two modes are known as "Two Touch" and "Four Touch" ( 2T / 4T ). The second mode ( 4T ) is useful for long runs of seam welding, where it is not necessary to keep holding the trigger depressed.
The third position is for Stitch Welding, where the machine will automatically stop and restart the welding process as the torch is moved, creating gaps in the weld bead which allow cooling. The stop/start time duration is controlled by the timer potentiometer(s).
The variable resistor on the back of the electronics box may be the Burnback control mentioned by daleyd in post #2.
This circuit allows the arc to continue for a short variable time after the wire has stopped feeding, which causes the wire to melt back inside the gas shroud, so there is no need to cut off excess wire before starting the next weld.
Does the MIG wire remain "live" for the time that it wrongly feeds an inch out, after you have let go of the torch trigger switch? ( i.e. you can arc with the tip of the wire ). If the wire feeds out but does not arc, there is a fault in the motor brake. If it feeds out and can arc, the contactor may be sticking "on" after the trigger switch is released. The contactor is the white component mounted on the chassis under the electronics box in your first photo.
Maybe there is just a brief spark, caused by the charge remaining in the smoothing capacitors. This voltage should be discharged by a bleed resistor across the capacitors. Your first photo in post #8 shows what looks like non-standard wiring for this resistor.
Circuit diagram for the PCB may be the one in post #16 here:
Migatronic Automig 180 Mono
Please can anyone tell me where I can obtain a spare control PCB for a Migatronic Automig 180 Mono or a circuit diagram for the PCB?
www.mig-welding.co.uk
Ok so removed contactor and took apart all clean, stretched spring a bit and put back. Still faulty so checked further and it seems every 5th strike wire stayed live until stopped moving and contactor seemed to prove this as click off was longer than other 4. At this point feed motor stopped working. So investigated 3 position switch, mine 10 position, found 1 position where contactor clicked on and off as required, so maybe this potentiometer switch was the fault but cant prove now as no wire feed.
mike 109444
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Post number 7
Wire-feed issue with migatronic automig 180
Hello everyone, I've browsed this site quite a bit while playing with a clarke no gas mig but decided to sign up to see if anyone can help me with this problem. I have picked up a migatronic automig with a wire feed problem. It does not appear to be the same issue as listed in this thread...
www.mig-welding.co.uk
It sounds as though a new fault - maybe a loose connection - has occurred during your work on the contactor and the 3-position mode switch. That switch must be new, and some of the other wiring looks like it has been modified. I would start by checking all over for loose connections and poor solder joints.
Apart from the wire feed now failing, do the contactor and the gas valve still operate?
Apart from the wire feed now failing, do the contactor and the gas valve still operate?
