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Thread: Mig welder problem

  1. #1
    Join Date
    Feb 2014
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    989

    Default Mig welder problem

    Something's gone wrong with my Lincoln 175 mig welder in the past year or so, and hoping you guys can give some suggestions what to look for. I've been welding for 20+ years, but don't know much about the electrical side of mig welders and am not an electronics guy other than some general basics and theory.

    This welder has always worked really well for me in the past, but lately is acting like maybe the duty cycle is really low. It'll start off a weld with that nice sizzling bacon sound, but after a short time (seems to vary with power applied) the sizzle cuts back to a soft hiss and the weld kind of beads up with very little penetration. It does maintain a spark during that time.

    I'm guessing maybe some capacitors went bad, or ?? The welder is stored in my unheated garage; our weather is pretty mild here but temps have gone down to about 10-15* F in the last couple winters so maybe something froze? Just guessing wildly there...

    Any helpful suggestions appreciated. I do know sending it back to Lincoln may be the best option, but maybe it's an easy fix and I don't know what I don't know.

  2. #2
    Join Date
    Mar 2015
    Location
    Central Ms
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    1,185

    Default

    Sounds like you're right that a cap is failing. Cold does some weird stuff. My old tractor wouldn't start the other day. Cleaned points, replaced the capacitor, have sparks when shorting points, but no fire from 2 year old coil. Tried an old coil that had been in the warm garage, and it fired right up. Maybe moisture gets inside these things from temperature swings.
    “I know lots of people who are educated far beyond their intelligence”

    Lewis Grizzard

  3. #3
    Join Date
    Dec 2018
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    Tucson
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    89

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    Every mig welder I have pulled apart due to failure was because of metal dust shorting the board.

    The other thing is that your liner may be dirty. That is real easy to test.

  4. #4
    Join Date
    Oct 2005
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    British Columbia
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    Default

    It'll start off a weld with that nice sizzling bacon sound, but after a short time (seems to vary with power applied) the sizzle cuts back to a soft hiss and the weld kind of beads up with very little penetration. It does maintain a spark during that time.
    Not saying that this is the problem, but from your description it almost sounds like the wire feed is slowing down drastically. As we all know it is the wire feed rate which controls the amperage so a wire feed speed reduction could be the culprit here. This would be easy to check when the problem occurs just to narrow it down and eliminate that variable.

    Does the machine return to normal later, how long? What triggers this problem, arc on time, gun or cable movement?
    Home, down in the valley behind the Red Angus
    Bad Decisions Make Good Stories

  5. #5
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    Nov 2018
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    Estonia
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    153

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    That is a modern inverter based machine, right? With a switch mode power supply, not the old school iron core transformer, I assume? In that case the possible reasons for it acting strangely are so numerous that spotting the right one at a distance may be close to impossible.
    But the more obvious and simple ones can be checked for starters: bad connections, dirty liner, worn tips, any obvious visible damages, conductive dust on the circuit boards, irregular feed rate of wire. If none of these is the reason, then it most likely is a problem with the power supply electronics. Or if one is lucky then it is the wire feed electrics department. Diagnosing and fixing that takes some electronical knowhow and at least a decent scope to spot any alarming distortions in waveforms.

    Old school iron core machines are way more forgiving and foolproof in that sense. There are really just a couple of things that can be wrong with one of these and usually they are an easy fix.

  6. #6
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    It is a transformer machine. Sounds like caps to me.

  7. #7
    Join Date
    Feb 2014
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    989

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    markx, I don't know enough about these to answer your questions about the type of machine. It's a Lincoln 180 that I bought new about 10-12 years ago. I couldn't tell you anything about the electronics inside.

    Dedave, could you elaborate on the dirty liner and what I'd test?

    Several of you mentioned iron dust; I can certainly take things apart and blow the dust off. I appreciate the suggestions.

    Willy, it seems to return to normal within a minute or two, maybe less but I haven't timed it. The problem is triggered by arc time, not gun movement as far as I can tell.

  8. #8
    Join Date
    Feb 2014
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    One more issue with this welder I'd forgotten about, which may or may not be related - I mostly use this welder with Argon/CO2 gas, but it has the ability to use flux core when current polarity is switched on the cable leads. It worked really well with flux core in the past, but last time I tried this it wouldn't weld well at all, mostly just fizzled and hissed without striking a good sizzling spark.

    I don't know if that could be another symptom of the same issue, but thought I'd mention it.

  9. #9
    Join Date
    Feb 2012
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    Dedave, could you elaborate on the dirty liner and what I'd test?

    Have you ever fitted a new liner to this machine? if not, after 10-12 years of welding, this could be the problem!. Sounds to me like it is a wire feed problem too. Take the wire feed off the wire, and run the welder to see if you can hear the motor, or see the wheel slow down or run erratically. Take the liner out and blow it through with compressed air, but if it is the original liner, fit a new one!!

  10. #10
    Join Date
    Feb 2012
    Posts
    263

    Default

    also check the tension on the wire feed, and check the drive wheel slot for wear.

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