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  • Willy
    replied
    Yup another good point worth checking, either way it sounds like the machine is not delivering full amperage at the weld. Another point of contact to check is the connection between the gun and the cable all the way to the contact tip itself. You'll have to disassemble the gun to check these items but it is a simple process detailed in your owners manual. As long as all connections are clean and secure you'll be good to go.
    Lots of low hanging fruit to pick before going deeper.

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  • Yondering
    replied
    That sounds like it's worth checking, thanks!

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  • scottly
    replied
    This doesn't sound like a liner or feed issue to me. I have a 25 year old Lincoln SP 135 that has seen lots of use and countless spools of wire, both flux core and solid, and it still has the original liner. I did have a failure once of the circuit board that drives the feed motor, and the factory tech support guy I spoke with told me the board had been re-designed, and replacements wouldn't be available for several months. I told him we couldn't wait that long, and if I had to buy a new welder to keep production going, I would be thinking twice before buying another Lincoln, but if he could fax me a schematic of the board and I could repair it, I would be happy. He faxed me the schematic, and it was fixed with $5 worth of Radio Shack parts.
    Your problem sounds like a bad connection to the torch; check the lug at the end of the lead used to switch polarity where it connects to the block where the torch plugs in. My welder had similar symptoms to yours, and I found evidence of arcing and eroding of the bolt. I also recall there was an issue with the screw that retains the torch to the machine?

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  • Yondering
    replied
    Thanks guys, that's a lot of great advice. Dedave, lots of stuff there I didn't know so that'll be helpful when I get a chance to dig into this further. (Probably the next time I need it - ha!)

    The description of liner issues does sound like a likely culprit. I used the welder briefly the other day and cranked down on the roller tension more than I've needed to in the past, and that did help a bit, so it may well be a liner issue.

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  • markx
    replied
    I agree on the wire feeding setup being the most probable cause....after all this is the part of a MIG that works the hardest in mechanical terms. Erratic wire feed rate can cause these and similar symptoms. Caps are a possibility, but usually their capacitance does not fluctuate up and down or reset itself within a few minutes of idle time, it is more of a one directional process. Could also be the power supply for wire feeder, I've had a sneaky situation with one of these (cheapo noname): the wire feeder would work nicely when the machine was not under load. But when the arc was struck, the voltage would fluctuate and be pulled down enough to make the wire feeder act erratically, causing similar problems.

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  • Dedave
    replied
    Originally posted by hermetic View Post
    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!!
    Sorry about the late getting back to you. I fitted alot of liners in alot of machines. Kinking is the first and most prevalent issue.
    Easy test to start with is release the feed tension and push the wire manually with your fingers. It should move fairly easy.

    The last liner machine I fixed was a lincoln small shop model. I was buying a guys bandsaw and we got to talking and his machine wouldn't work. Liner was clogged up. worked wire through a few times and pushed the dirt out the end. When I say worked the wire, you have to cut a nice square end and then pull it back into the liner and push it back out letting the blunt end carry whatever dust it can collect. Do not grease your liner.

    To remove your liner, is fairly easy. pull the nozzle and diffuser from the gun end, unhook the torch from the machine. There is most likely some set screw holding the liner brass fitting on the feed end. Rotate the liner as you work it out. Usually a counter clockwise rotation helps if it is really gummed up and stuck, but generally fairly simple and straight forward. Do not just pull without rotation if it is stuck, you will stretch the liner and render it useless or unfixable. Think lawnmower throttle cable of yesteryear.

    When installing the liner, it must be real close to proper length. Too long and it binds, too short and it will not sit into the diffuser proper and won't guide the wire as efficiently. When you pull the old liner, if you see kinks, most times they can be straightened if careful.

    At 12 years old, definitely needs blowing out. But if the damage is done, new board is in order. Usually that can be seen with a good flashlight and magnifying glass. Look for burnt areas, resisters usually. I had a nice miller that I bought cheap that burnt up that way. Make sure you unplug the thing before pulling panels.

    Hopefully the issue will be self evident when you pull the liner.

    Caps, drive motors,power transformers/coils are hearty on these machines. Welder repair shops like to tell you that is the problem. Schematic for the boards are impossible to get unless you are an authorized repair shop and even then the information is lacking.
    Last edited by Dedave; 03-20-2019, 02:40 AM.

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  • v860rich
    replied
    On my 220 amp Lincoln mig welder if it's not used for a long period of time the wire will get an oxidized coating on it and not want to feed properly, act just like you describe. I unspool a bunch of wire and discard that.
    I now have a felt wiper clipped on the wire just before the feed rollers, I spray the felt with PB Blaster or another lube so the wire gets cleaned before it enters the feed rollers, that will fix it for a while, at least until I forget to lube the felt again.

    THANX RICH

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  • Willy
    replied
    The wire feed speed feed rate is what controls the amperage and by the description of having an arc accompanied with no penetration and a hiss it sounds as if the wire speed is slowing down measurably at that point.

    Set the machine at a voltage and wire feed speed you know works well, verify this by laying down a short bead. Next while making sure that you aren't going to strike anything that is in the welding circuit, trigger the gun for 10 seconds and measure the amount of wire that has now exited past the contact tip. Multiply that figure by 6 to obtain the wire feed in inches per minutes. For example if 30 inches were spooled out during the 10 seconds and that figure is multiplied by 6 your wire feed rate would be 180 in./min.

    Do a bit of welding to the point that the problem reoccurs, then instantly repeat the above procedure in order to determine if the wire feed rate has slowed down from the figure you obtained when all was working as it should. If the amount of wire spooled out is shorter than before you would have a feeding problem. Which could be as simple has a dirty liner, a contact tip, drive roll tension etc.

    Let us know what you find and well go from there.

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  • Yondering
    replied
    Originally posted by hermetic View Post

    Have you ever fitted a new liner to this machine? if not, after 10-12 years of welding, this could be the problem!.
    I have not, but it doesn't get used a lot. Probably only 2, maybe 3 spools of wire since it was new.

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

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  • hermetic
    replied
    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!!

    Leave a comment:


  • Yondering
    replied
    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.

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  • Yondering
    replied
    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.

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  • BigMike782
    replied
    It is a transformer machine. Sounds like caps to me.

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  • markx
    replied
    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.

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