Lincoln 215 mig issue

[jmm03]

Hello all, got volunteered to troubleshoot a problem on a 215, hoping someone can help.
Machine will not weld at any setting on the rotary switch, will strike an arc but very spattery,almost like there is no gas.
good gas flow, checked by turning up the flow regulator all the way and checking by hand at the nozzle, changing the amount of gas has no effect on the weld, still spattery.
checked the liner and the drive wheels, smooth operation of the wire at all speeds.
removed the covers, blew out the machine, cleaned all the contacts on the rotary switch, they did not appear to have any corrosion or oxidation on them.
checked positive and negative connections and internal board connections, all tight, no obvious signs of arcing anywhere.
no change in problem after these checks.

any help would be greatly appreciated. Thanks, Jim

[ccawgc]

Check your polarity setting. Mig wire uses positive to the gun and flux core uses negative to the gun. Wrong polarity will cause splattering and poor pentation.
Lots of BBs.
Can you start an arc and keep it going if you do not move your hand?
Possible the arc goes out if you raise the gun even a little.
And find you can only keep the arc going is the tip is almost touching the plate.
If so there is a problem with the cap bank or the connections to it.
A properly working welder should keep and arc going with up to a 1 inch stick out.

[jmm03]

Hi CCA, thanks for responding, polarity is correct, connections to the leads tight, arc will start only in higher range on the dial, did not try backing away the gun but will. Will check the cap connections but what is a good way to check the caps,I don't have a capacitor checker.

[ccawgc]

Bad cap bank is low on the list of possible problems. usually show up in older welders.
caps are so large most digital meters with caps test can't test them.
and you have to disassemble it and test each cap alone. If you can find a meter that will read that high. Only other thing is to check it for loose or burnt connections and check the pressure plugs. look between the buss bars and see if there is a round plug.
If a cap is bad and build pressure it is suppose to release the pressure by popping out. if they are all pushed in they might be ok.
Right now I would start by checking the line voltage into the welder and make sure it is set up for that voltage. put you test meter on the line and try to start an arc.
voltage should drop a little. 5 to 10 volts. anything larger and you have a line problem. wire to small or bad connection at plug or breaker. If that is ok.
Look at every bolt together weld circuit connection. one might be burnt.
next I would move meter to the transformer secondary side.
one quick check is connect meter to 115 volt outlet on the welder and see what is reads and what happens when you try to weld. If voltage stays up line input side, cord and house wiring should be good. if drops way low, you need to look at the input connections.
Next with covers off, machine unplugged. find the weld diodes and cap bank.
follow the wires from the cap bank back to the diodes. this will be the DC side.
you want to connect tot the AC side of the diode assembly. Plug welder in and turn on, with gun trigger pulled voltage should be around 25.6(highest voltage set on switch) when not welding. then try to weld see how far it drops. write down the numbers. then move one meter lead to the contactor. one side will read zero and the other will read about 25.6VAC. If both read zero, move the other lead.
pull trigger again. voltage should react the same. if the drop is way less. move leads to across the contactor. pull trigger and try to weld. voltage should be Lees than one volt. anything higher and contactor is bad. Just be careful with live voltage testing.

[jmm03]

Thanks for your help CCA, the machine was working the last time they used it supposedly, fed from the same location it is plugged into now but I will verify. The mechanic who's machine it is checked all the connections and looked for any obvious signs of internal arcing ,he seems pretty sharp so I believed he would see something obvious. I will hopefully be able to get back to do the electrical checks myself this weekend and try your tests. Jim