Need help with Lincoln 180 Dual not welding properly .

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Hi all- first post and I really need some help!  I am a building contractor and use this welder mostly for tinkering around the house (Wheel Horse tractor accessories, currently building a go kart with my 17 year old…) but we have put quite a bit of time on this machine over the last 4 years or so.  In the middle of a few projects so need it up and running!  Help!OK so it has been running great until Friday night. It ran out of wire so and once the new roll was in the welds were porous and dirty looking and instead of the nice frying bacon sound its more staccato and definitely louder.  Like the machine is delivering short pulses of electricity instead of a nice steady flow.  Weld penetration is terrible too- with the voltage all the way up the welds are basically sitting on the surface and can be knocked off with the slag hammer easily.I have done the following: confirmed that the gas is correct 75/25 (I have 2 bottles both still have gas and result is the same with either- bad welds persists with gas flow turned way up too- welding inside so no wind, metal ground clean), checked O Rings at base of gun to be sure they are good and no gas is escaping there, confirmed that ground wire is on correct terminal (wasn’t changed for the last 4 years), jumped across ground clamp with a jumper cable to confirm good ground/ground cable and clamp, gun works as it should (trigger pushes wire and you can hear/feel gas flow).So took off the cover on this thing and I have an electrical tester and figured I would see DC voltage of some sort inside this thing but I am not 100% sure what to check.I guessed that the 2 large nuts here would be the output of the rectifier (thing that converts from AC to DC) but get no voltage there AC or DC.  Can anyone offer any suggestions?  I promise to post pics of the stuff I make lol.Pictured is the 2 lugs I was hoping to find DC power on, the appearance of the welds and the state of the go cart project.   Thanks

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Reply:Have you confirmed that gas comes out of the gun when you pull the trigger? You are definitely not getting gas would be my read...maybe the gas solenoid is stuck closed or needs to be replaced.Miller Multimatic 255
Reply:

Originally Posted by Louie1961

Have you confirmed that gas comes out of the gun when you pull the trigger? You are definitely not getting gas would be my read...maybe the gas solenoid is stuck closed or needs to be replaced.
Reply:Is your diffuser on the gun?  Is your powerlug and male end of the cable properly seated and tightened.   What wire did you install,  vs run out of.
Reply:

Originally Posted by tapwelder

Is your diffuser on the gun?  Is your powerlug and male end of the cable properly seated and tightened.   What wire did you install,  vs run out of.
Reply:Power lug connecting the gun/hose to the machine.  If you drag the machine by pulling the gun it could separate the connection (not saying I would do something like this).  The brass end of the liner should be visible from inside the machine  and flush with the roller guide.  Your gas enters the line at that point if offset it will not flow fully.
Reply:I'm no expert, but would start with some basic tests:With the gun/power cable, and the ground cable both removed, what is the voltage between the ground connection and the gun inlet (control cable still attached so trigger works)? What are the resistances from connector end of the ground cable to its clamp, and from the gun cable connector to the copper feed tip? Do you have any kind of seal at the feed side of the inlet cable, just past the rolls? If so, are they working well? How is the gas tubing between the solenoid and the wire feed? Leaks can allow air to enter while gas isn't flowing, then be carried on to the tip when it is. Could the new wire actually be hollow and have some sneaky Chinese spies still trapped in it? They don't cook well...


Reply:

Originally Posted by tapwelder

What wire did you install,  vs run out of.
Reply:

Originally Posted by Oldiron2

I'm no expert, but would start with some basic tests:With the gun/power cable, and the ground cable both removed, what is the voltage between the ground connection and the gun inlet (control cable still attached so trigger works)? What are the resistances from connector end of the ground cable to its clamp, and from the gun cable connector to the copper feed tip? Do you have any kind of seal at the feed side of the inlet cable, just past the rolls? If so, are they working well? How is the gas tubing between the solenoid and the wire feed? Leaks can allow air to enter while gas isn't flowing, then be carried on to the tip when it is. Could the new wire actually be hollow and have some sneaky Chinese spies still trapped in it? They don't cook well...


Reply:Just putting this out there.For all wire types used in dual shield welding, the suggested polarity is DC+Straight Fluxcore is DC-Lincoln 330 MPXModified TombstoneLincoln LN-25X-TVTMagnum PRO 250LX GT Spool Gun¼ Ton of Torches OFC-A / OFG-ASMAW FCAW GMAW Air Carbon Arc Gouging#Freebird Welds
Reply:See photo above for results with wrong polarity lol