pipeliner won't weld

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Hello folks.I'm hoping someone here can help me sort out my Lincoln. I think it's a very old SA200 or 250. Round, not hex. Continental F-head. I've owned the machine a couple of years. Before I got a hold of it it was stripped  of all covers, gauges, receptacle etc. All she's got are two amperage controls and cables. This machine has never skipped a beat welding like a champ, until a couple of days ago. Suddenly there's no arc. I measure 0.7 volts across the cables. The main and exciter brushes were all in great shape and free in their holders but I cleaned them anyway. Holding the engine at a fast idle makes no difference. Lifting an exciter brush while the machine is running there's no arcing from brush to commutator. There's no PC on this old girl and no flashing diode that I can find. I've read about flashing the exciter and have tried it with no success. Positive to right side brush holder looking at the welder right? I've manipulated the amperage controls while shorting the cables, again no difference. Both commutators look great. Any ideas? Where can I measure resistance or voltage to troubleshoot the problem? There was no degredation of performance prior to it quitting so I fully expected to find a wire had come adrift or something equally simple but nothing is obviously awry and I'm at my wits end.Thanks, Greg
Reply:Do you have any power even partially to your 110 receptical ?Ken
Reply:There's no receptacle Ken. Just a handful of taped off wires to be sorted out when I get time to make a project of this machine instead of using it on other projects.
Reply:I had an old Hobart portable welder powered by a 6cyl. gas engine. It would run fine but wouldnt weld at all. A guy at the electric motor shop told me that that it could have lost its polarity. He advised me to take the two main wires loose from the exciter brushes. Run one of the wire to a battery on the neg. side. Take another wire and hook to the other side and run it to the positive side of the battery. Dont hook it up, just strike it across the positive terminal. It should arc. Do this a couple of times. I tried this and then hooked up the wires to the brushes like they should be. Then when I fired it up it started welding and I never had any further problems. The motor guy told me that an electric motor that sits for a long time will lose its polarity, especially older DC electric motors. Hope that helps.
Reply:Sounds like you have a 46 Lincoln Sa200 shorty. In 48 they had 110 recepts. You need to check your exciter coils and exciter armature (in bullet housing). Check for broken or rat chewed wires. No spark from the exciter brush when pulled from armature (while running) sounds like faulty coils or armature.
Reply:I would definitely check the lost polarity thing. You have to flash the generator on old Harleys any time you disconnect the wires (don't ask me how nuts it drove me the first time I changed the brushes). I also remember something about remnant magnetism (in the armature if I recall correctly) and it's loss pertaining to dc generators but it has been so long I can't recall just what it was.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:Thanks for the replies. I tried to flash the exciter but it didn't work. I've taken the armature and field windings out and they look to be in perfect condition but I dropped them off at an auto electric rewinding shop to be tested in desperation. I'll have the verdict tomorrow. If there's no fault found I have no idea what to check next.
Reply:Well I'm told the exciter armature has a short. I'm going to look for a replacement. Are they fairly universal or do I have to worry about the year or model etc? If I can find a used one will my existing field windings work or do I need to get the fields with it? I can post a picture of the dead armature if it helps. Thanks everyone.
Reply:hello to all, I have a similar problem with a used ranger 10,000 i just got.  it'll fire up just fine but i tried to weld nothing happens like no power going through leads. any suggestions