Welder Woes

[Bill in IL]

I have an inverter welder that I use for stick, TIG and MIG. Its a Invertec V300pro model from lincoln.

Tonight while MIG welding using a LN-7 wire feeder running 25 volts or so it seemed to loose power. Basically it quit welding and started heating the wire red hot and making a pile of twisted wire. I would quit and start again soon after an inch or so it would do it again.

After thinking of it while stick welding it sometimes will burn out for no reason. I just thought it may have been my technique, rod, settings but starting to blame the machine.

Any suggestions as to how to dig deeper and test this thing? Are there common problems with these machines that cause symptoms as described? Is it maybe just time to look for a new machine?

 

[Anonymous-0]

I hate to be the bearer of bad news but it might be a machine problem. I know of a huge shop up here(Dacro industries) that was trying out Lincoln inverters and had lots of problems with them. They told Lincoln to take them back and got Miller inverters. Also at the largest apprentice training facility in Canada, NAIT, they had leased Lincoln 350 inverters and couldn't wait to get rid of them. They have some Miller XMT 304's that they like and leased the Lincolns but after expanding their facilities purchased a whole whack of the newer Miller XMT 350's which they like even more. I was talking to one of the instructors a couple years ago and he said the Miller inverters were way better than the Lincoln inverters and they rarely had problems with them. The Lincolns were problematic and not nearly as reliable. NAIT tries to support everyone in the industry since they are a training facilty and want to have the latest technology. I'm not trying to bash Lincoln but Miller is better for an inverter. However for a 350 amp all in one MIG unit, the Lincolns were more dependable than Millers according to a shop I worked in that had both. Dave

 

[Bill in IL]

I think this v300 is the previous model to the 350.

I have had it for 6 years or so under basically weekend use. I bought it used and it looked like it had a hard life. I had to replace the input rectifier when I bought it.

This morning I tried it and ran 12 inches or so of weld before it started acting up. So the problem is responding to heat buildup in the components.

Not really looking to get rid of it yet but does anyone have ideas as to what breaks down in these machines. Would consider putting some money into it as long as I can find parts from a supply house and not lincoln. That input rectifier from Mouser was 80 bucks but 320 from lincoln.

 

[Anonymous-0]

Inverters can be expensive to fix. The early Millers which were blue Powcons weren't as good as the XMT 304's and I know a guy that bought a used one for his shop. I think he spent $1200 fixing it and something went wrong with it again a few years later. You should check with some of the really big Lincoln dealers or repair outfits. They should know what problems they have and how reliable they are. Dave

 

[trucker40]

Maybe you can look for something getting hot somewhere might be a bad connection.Maybe have somebody weld with it and look at connections and see if anythings hot or sparking anywhere.I seem to have a lot of trouble with my ground cable so I weld it to my work sometimes and it clears up some minor problems with my MIG.Usually just a small tack is all it takes.

 

[Greyhorse]

Take it to a shop that works on welders and have them check it out. A machine like that is going to be too complicated for the average DIY'er to figure out most likely. It'll save you a lot of headaches.

 

[bc]

Bill, you might have a thermistor going bad it in. They are designed to take so much heat and then they shut down the part they are controlling. There are probably multiple thermistors including one for the wire feed. If it is not putting out abnornal heat, then a thermistor may be one of many causes. Or else it is putting out too much heat. Could be a bad fan motor or dirty fan and bearing not allowing the fan to turn. If the cooling fan doesn"t come on at all, then it or a controller could be bad.

Try putting a floor fan next to it to blow on it and see if that helps and let us know.

Clean and lube the tip and wire feed mechanism as well.

Does it always have enough current on the wire to melt it or is that intermittant? Does it always stop feeding wire?

I"m not sure how you can have a hot pile of twisted wire as that requires the wire feed to work and have hot current to the wire at the same time. If this is the case, then I"d think about a loose ground somewhere.

 

[Bill in IL]

The wire feeder itself it working fine. I have no troubles feeding wire.

The fan is working in the unit cause it is rather loud and makes its presence known.

I got the cover off the unit and cleaned it with compressed air. Was dirty but not alarmingly dirty.

I will check into the thermistors. The manual has a wiring diagram but a schematic would be more helpful. It shows a lot of things but the driver board and switching boards are not broken out.

I don't have much faith in the local shops. They just replace boards and hope it helps.

 

[bc]

I'd still try a floor fan. The cooling fan making noise suggests the motor is going bad and/or the bearings are gummed up all of which could cause it to draw too much current and maybe cause a protection part in the circuit to cut out.

In my old tv repair days, we used a can of component freeze spray (basically liquid propane) to spray on component at a time on a circuit board. The frozen open component would then close and work till it warmed up. Just about need 2 people, 1 to weld and 1 to check circuits. The freeze spray may not find a shorted component.

There are other circuit tests (ac & dc voltage, resistance, continuity, amperage) you could run but I don't know anything about your welder circuit so I probably can't help you.

Be careful, lots of deadly electricity in one of those. Might be a good time to get the rubber gloves, sneakers, and get your rubbers out of the closet to put over your sneakers.

I'm not sure I understand your problem. If it feeds wire ok, and the wire get red hot like it should when it arcing with the metal, then I don't see how you are getting a wire mess. The lack of electricity on the wire would cause it to stop welding but it shouldn't get hot at the same time.

 

[Anonymous-0]

I think the amperage is going way down but not not completely to nothing. The wire feeder is seperate and doesn't run off of arc volts. Being that the wire is so small, it wouldn't take much amps to make it turn red hot. Dave