No Wire Feed 140xt

  1. B-Bulbs New Member

    Messages:
    8
    Location:
    Scottish Borders
    Hi, I have a Sealey Mightymig 140xt & it has stopped feeding wire.

    From the start - I bought a new torch,fitted it and then I had no wire feed. All I did was disconnect the existing wires and plug in the new ones.

    I started looking online and came across a few threads on this forum with what sounded like the same issue, most of which pointed to either the feed motor or the wire feed pcb. I purchased a new feed motor first but the problem was the same. So I next purchased the pcb, £82 ouch!, and the problem is still the same.

    When I pull the trigger you can hear the relay and the sound you get when the the wire is stuck.

    Any help will be much appreciated.
     
  2. eddie49 Member

    Have you tried feeding wire with the copper torch tip removed?
    With the wirefeed pressure roller slackened, can you freely pull wire out of the torch?
    Have you tried completely slackening the brake on the wire spool?

    Apart from the faulty wirefeed, does the gas solenoid ( if fitted ) and the welding arc function correctly?
     
  3. B-Bulbs New Member

    Messages:
    8
    Location:
    Scottish Borders
    Thanks for the reply.

    I haven't been able to get the wire to feed up to the torch. As soon as I replaced the torch the wire feed stopped working. I purchased a new wire feed motor thinking that was the most likely prob but there is no difference with the new to old motor, both work with a separate power supply.
    My next thought, after reading threads on here that sound exactly the same, was that it must be the pcb and as I'm no good with circuits/electrics I thought it would be easier/safer buying a new pcb but its still the same.

    It does seem to arc properly, as I discovered in the house and nearly filled my boxers oops! I'll give it a proper check this afternoon.

    Could it simply be a wire from the pcb to the motor? If so how would I go about checking?
     
  4. eddie49 Member

    The reason I asked about the arc is that the power for the wirefeed motor is often tapped off from the main welder output, then fed to the motor via the speed controller circuit on the PCB. There may be two thin wires, perhaps red and black, attached to the rectifier plates at the same places as the heavy cables that carry the high-current weld power. The voltage at that point will be something like 15v to 30v DC, it will vary depending on the selected weld power range.
    Those two wires can be traced to the PCB, and then on to the motor. If you shut off the gas, slacken the pressure roller, and press the torch trigger there should be from 8v to 20v DC across the motor, as you wind the speed control up. Does the grooved drive roller attempt to turn at all?
     
  5. B-Bulbs New Member

    Messages:
    8
    Location:
    Scottish Borders
    Thanks for the reply.

    It is arcing well.

    The roller makes no attempt to turn at all.

    I've attached a picture of the new motor connected to the new pcb.

    There is a red wire and 2 black wires that come from the back of the motor. The red goes direct to the pcb as does one of the black ones and the other goes and connects to the plate under the fan.
    IMG_20200423_114244.jpg
     
  6. a111r Member

    Messages:
    888
    Location:
    London
    I had something very similar on a larger old Sealey with the maybe same wire feeder.
    I mixed up the feed motor casing screws, putting a larger one where it should not go - it impinged upon the internal gear train, thus causing zero feed roller drive.

    When you fitted the new torch, the problem appeared. You may well have had to dismantle / remove some of the wire feed casing to fit it.

    Try removing the screws, the one in the middle near the liner will be the one I reckon ...
    https://www.ebay.co.uk/itm/133387648049

    The gear train is plastic and not very robust. Another possibility is that a tooth has broken and jammed it, although when this happens the roller usually still rotates but slips under tension and the gears chatter.
     
    Last edited: Apr 23, 2020
  7. Seadog

    Seadog Forum Supporter

    Messages:
    6,972
    Location:
    NE London - UK
    The black wire will be the negative. A common fault is the potted transformer, the red block on the PCB.
     
  8. B-Bulbs New Member

    Messages:
    8
    Location:
    Scottish Borders
    Thanks for the ideas guys.

    The wire feed motor is a brand new unit, its just wired up, its never been screwed on.

    Hopefully its not the transformer as its a brand new pcb.
     
  9. a111r Member

    Messages:
    888
    Location:
    London
    Ah, I understand now.
    The 24v dc motors separate from the wire feed units via 2 screws, but you're talking the whole wire feed assembly.
     
  10. eddie49 Member

    The PCB is brand new, and the fault was the same with the old PCB. The potted transformer on the PCB only supplies power to the relay, and the relay is operating correctly. The main transformer gets power when the relay closes, and the secondary of that transformer sends power through the rectifier and it can strike an arc.
    You need to trace the thin red and black wires with push-on tags from the rectifier plates to the motor and to the PCB and check them for breaks, or use a meter to confirm continuity and check voltages.
     
    a111r likes this.
  11. B-Bulbs New Member

    Messages:
    8
    Location:
    Scottish Borders
    I'll give that a check this afternoon.

    Thanks
     
  12. B-Bulbs New Member

    Messages:
    8
    Location:
    Scottish Borders
    I finally managed to get time to have a look, it's been a hectic week.

    I tried simply replacing the red and black wires with new to see if that was the problem. Unfortunately it's still the same!

    How do I go about checking it with a multi-meter? I never know which settings to use on it or whether the thing being tested should be powered up or not! :dontknow:
     
  13. eddie49 Member

    It's odd that the machine seems to have power to weld with, but that never reaches the wirefeed speed control circuit on the PCB, nor the motor.
    To check where power is getting lost, as long as you are comfortable working around powered-up live mains equipment:
    - open the casing
    - make sure that none of the loose components can short to the chassis
    - set your meter to 200v AC, and connect to the secondary output of the main welding transformer. This will be two very thick solid copper or aluminium wires, emerging from the transformer and bolted to metal tags at the rectifier
    - plug in the welder, switch on, and press the torch trigger. Depending on the welder power setting on the range switches, you should see 15v to 35v AC

    The transformer secondary output is also the AC input to the rectifier. The DC output from the rectifier is on the square aluminium plates. Set the meter to 200v DC and connect to the bolted connections on the rectifier plates. One of those connections is a heavy black flexible cable that goes to the torch, the other one is a solid wire that goes to the inductor. This is also known as the choke, it looks like a transformer but only has one winding, and it is mounted on top of the main transformer. Plug in the welder, switch on, and press the torch trigger. Depending on the welder power setting on the range switches, you should see 15v to 35v DC at the output from the rectifier.

    As well as the above two heavy connections, you should see two pins for push-on tags. [ There is also a wire-ended component, a spike suppressor, soldered across there.] Check that those pins, and the push-on tags on the two thin wires, have the same DC voltage.

    One of those wires - black - goes to the motor, the other - red - goes to a plug on the PCB. Check for the DC voltage, 15 to 30v DC, between the tag on the black wire at the motor and the plug on the red wire at the PCB.

    Finally check for a variable DC voltage between the tag on the black wire at the motor and the red wire at the motor. You will need to clip the meter leads on there, press and hold the torch trigger, and rotate the speed control knob. You should see from 8v to 25v DC, varying as you turn the knob, and also stepping up as you alter the welding power range switches.
     
  14. B-Bulbs New Member

    Messages:
    8
    Location:
    Scottish Borders
    I can't believe it, I AM SUCH A TOOL!!!

    If you look at the picture you can see a black wire connected to a grey wire hanging down. This should be connected to the small tab above where the cable for the torch is attached! :ashamed::ashamed::ashamed::ashamed:

    Connected it up and hey presto its alive! I have moved these wires out of the way a million times and not once until I was reading your instructions that it suddenly dawned on me. :doh::doh:

    In my defence I don't remember taking that off when I changed the torch wiring, it possibly popped off when I first opened up the side panel as it was quite a loose fit when I popped it on to check. (that's my excuse anyway)

    I've already had the kids mocking me and it'l only get worse when I tell the auld man so have at it guys I deserve some stick for this one!

    Thanks for all the help, at least if this problem pops up in the future I will have an idea of where to start. :whistle:
     
    a111r likes this.
  15. eddie49 Member

    Thank you for the update, and the good news!
    I did see that the tab was not being used, and the black and grey wires hanging near it, but I never made the connection.
    I thought there was a red wire on the aluminium plate, but in fact it's just red paint.
     
    B-Bulbs likes this.
  16. B-Bulbs New Member

    Messages:
    8
    Location:
    Scottish Borders
    I never made he connection either LOL I'm still kicking myself!

    Now I can get going with a new hobby, I got myself a gas forge and anvil. I've always wanted a go and now I have plenty of time, why not!
     
  17. MikeAG New Member

    Messages:
    1
    Location:
    Essex UK
    Rather than start a new thread with precisely the same problem but a slightly different welder model, I thought I'd jump into this one. As I'm new, please let me know if I should be starting a new thread instead.

    I have a Sealey 130XT, and the wire feed has died. I only use the welder intermittently, and it's been a couple of years probably, but when I tried it a couple of days ago it refused to work. I have taken it apart, and removed the drive wheel, but only get a little click as the relay closes when I pull the trigger. There is no action from the motor at all. On a power tool I would immediately replace the bushes and clean the commutator. A couple of times it has jumped into life and turned, say, a quarter turn, but that's it. I've opened up the gearbox and everything is turning freely in there.

    What are my options? I can't even see the model on the Sealey website, so if I need a replacement wire drive unit I don't know what to order........or are they the same in all of the smaller welders?

    As an aside, does anyone know if this model is suitable for gasless wire?
     
  18. a111r Member

    Messages:
    888
    Location:
    London
    Welcome!
    You should start a new post for this. You'll get more responses, doing so.

    You can test the motor via a 12v battery, but usually it's not the problem.
    Yes, you can convert it to reverse polarity for gas-less wire, afterwards.
     
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