# Gas flow problem w/ mig welder



## 150mud (Nov 23, 2012)

I have a Cornwell Tools MG 255 mig welder for about 6 yrs. Lately, while in middle of welding the gas would shut-off. I have checked for any loose connections. Found none. So I'm thinking it could be in control circuit broad. Anyone had this type of problem with their mig welder? Thank you in advance.


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## Tony Wells (Nov 23, 2012)

Does the current to the solenoid drop out when you lose the gas? You may have to enlist some help to watch a voltmeter while you weld to see. If it does, then it's likely a control board issue. Does it happen and then you have to wait a bit and start your weld again before you get the flow back, or can you immediately restart? Does the length of time before it shuts off vary, maybe decreasing as you work through several welds? If so, it may simply be a heat issue. That could be several things aside from a bad component on the board. Open the cabinet and put a fan on the control board and see if it has any effect on it. In 6 years, certain components on the board could become questionable. Electrolytic capacitors in particular. They don't age all that well, and it is unlikely that top quality capacitors were used in its construction. That would probably be the first thing I would look at from the board. Of course, if there are heat sinks on any of the solid state components, any dust or dirt that gets on them takes away their efficiency, so a good blowing out with compressed air would help, if it is dirty. If it's also oily, of course the air won't clean it well, so you would have to use some electronics compatible spray cleaner. CRC makes a decent one.

That's all I can think of at the moment.


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## clarkie54 (Nov 23, 2012)

Hello from Clarkie. Some times with cheap regulators the seat fails. This is caused by leaving the flow control knob wound in when fitting the reg to a fresh cylinder. The sudden inrush destroys the seat and usually the flow gauge is moved off it's stop. Story is un wind the reg before fitting to a full cylinder.


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## 150mud (Nov 23, 2012)

Thanks for the replies. I'll try timing it & see if I can restart welding right away. As for the control panel being dusty or oily, no problem there it's spotless. I'm away from home now. Holiday thing! Will be a week before I be able to do some more checking. I'll post the results then.


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## Pontiac Freak (Nov 23, 2012)

Is that welder a re-badged Lincoln or other large brand?  I know some Snap-Ons just re-badged someone else unit.  If it is, then you might be able to pinpoint the problem to a common fault with a certain make and model.  For in depth welder help you might try these sites they have some guys that live for welding and are great help ) http://weldingweb.com/index.php http://www.millerwelds.com/resources/communities/mboard/forum.php? http://www.shopfloortalk.com/forums/forumdisplay.php?f=25


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## David (Nov 23, 2012)

I would try process of elimination before changing circuit board.  My experience has been when the gun trigger is squeezed, it activates an electric solenoid to allow gas flow while welding.  You can possibly open side cover and find this solenoid valve, install volt meter and have someone watch while welding to see if voltage is dropped.

Most of the time, my problem has been with the gas gauge or flow meter.  One place to look is the fitting on the outflow side of the gauge.  There is a metering orifice in most fittings where the line attaches to the gauge.
There may be contamination here.  If the gauge has been changed at some point, may be wrong metering orifice for your machine, basically running out of gas.

Is the gun liner kinked or worn to point where wire feed is partially restricted?

I've had same concerns as you on circuit board problems with gas flow, but so far has been something else.

Good luck.

David


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## 150mud (Nov 24, 2012)

Thanks for your advices on checking other possible components, before replacing control broad.
As for re-badge mig welder. The only name I seen is Nu-Tec on the torch handle. Inside the panel door near the control broad. Seen Made In China label. Don't know who makes the welder. Will post some pictures when get back.


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## Philco (Nov 24, 2012)

David said:


> I would try process of elimination before changing circuit board.  My experience has been when the gun trigger is squeezed, it activates an electric solenoid to allow gas flow while welding.  You can possibly open side cover and find this solenoid valve, install volt meter and have someone watch while welding to see if voltage is dropped.
> 
> Most of the time, my problem has been with the gas gauge or flow meter.  One place to look is the fitting on the outflow side of the gauge.  There is a metering orifice in most fittings where the line attaches to the gauge.
> There may be contamination here.  If the gauge has been changed at some point, may be wrong metering orifice for your machine, basically running out of gas.
> ...



Had the same issue with my mig welder & like David mentioned it turned out to be debris in the metering orfice in the regulator .
Hope this helps 
Phil


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## savarin (Nov 25, 2012)

I had a similar problem with my mig in that I couldnt get enough gas flow.
It was a heap of metal swarf in the gas inlet on the gun itself.
I happened to renew the gun a few years later and the the new gun had the same problem so I put it down to a manufacturing fault.
Since cleaning out the swarf its performed flawlessly.


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## Postman11 (Nov 25, 2012)

150mud said:


> I have a Cornwell Tools MG 255 mig welder for about 6 yrs. Lately, while in middle of welding the gas would shut-off. I have checked for any loose connections. Found none. So I'm thinking it could be in control circuit broad. Anyone had this type of problem with their mig welder? Thank you in advance.



What you describe could result from several things.  I have seen gas flow problems result from the mig gun not being fully seated in the wire feeder mechanism.  The gas enters the stretch between two O rings.  If the holes do not line up the gas flow can be interrupted.  Also, bad or missing O rings and plugged gas diffusers.

Lift the pinch roller, trigger the gun, and see if the gas flow is and remains normal without feeding wire through the cable/hose.  How long does the gas flow?  Does it stop abruptly?  

The gas soleniod may or may not be fed from the control board, but that would be the last place I would suspect or look for a problem.  Check the electrical drawing, but I would suspect another cause...


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## 150mud (Jan 21, 2013)

Update on my mig welder. First of all,sorry for not updating sooner had the flu, not good. As for the mig, found the problem with the regulator. Took all the fittings off found some  thread sealer loose. Causing flow problem. The welder back to 100% in operating condition. Thanks to all who  have response & advices.


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