[Burnt Glove]

So I got my 41 SA200 fired up.and running today. Machine probably hasn't ran a bead in 40 years. I have not had a chance to check the RPM yet, but I did run a few beads of 7018 1/8" with it today to see if it would weld and to see if the idler was working on it. I set the selector switch to 100 (it's lowest setting) and set the voltage down to its lowest setting and ran a short bead. It seemed a little cold for an 1/8" rod, so i turned up the rheostat to 20 and ran another bead with it. It seems to run it bit better but it acts like the arc force is turned all the way up, if the machine had an arc force setting. I am thinking I need to check the ocvs and RPM before anything. Does anyone know what the OCVS should be on this machine?
Thanks in advance.

 

[Adam Arc]

Max Output on the first range should be around 100 amps. A little hot for 3/32" 7018 and cold for 1/8". OCV should be the same as any other short hood.


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[Burnt Glove]

Max Output on the first range should be around 100 amps. A little hot for 3/32" 7018 and cold for 1/8". OCV should be the same as any other short hood.


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RPM is somewhere around 1300 no load. OCV is at 85 volts. Exciter voltages is at 155. I have also noticed that the positive exciter brush is on the left, rather than on the right side. Not sure how that has happened. Not even sure how to get my exciter voltage down without lowering the RPM even more, which would drop the OCV.
Bob Crow from Lincoln electric told me the RPM should be 1500 no load, exciter voltage 115-120, and OCV 85 machine warmed up and set at max.

 

[Adam Arc]

I've talked to Bob quite abit. Nice guy.
Sounds like something is up in the exciter end. Polarity is backwards and hot. Start with setting the toms, switch the polarity and reseat the exciter brushes.


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[Adam Arc]

Not toms, rpms.


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[Burnt Glove]

I've talked to Bob quite abit. Nice guy.
Sounds like something is up in the exciter end. Polarity is backwards and hot. Start with setting the toms, switch the polarity and reseat the exciter brushes.


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Yeah Bob is a good dude. Helped me out a bunch.
Not sure how to switch the polarity. I'm guessing I should flip the exciter coils around????
Correct me if I'm wrong, but doesn't the RPM set the exciter voltage? So to bring down the voltage I should reduce rpm?
But I do agree. I need to get the exciter polarity straightened out first.

 

[duaneb55]

To reverse the polarity, just re-flash applying 12V(+) to the right brush and (-) to the left. Do this with the unit off and one of the exciter brushes isolated from the commutator to prevent a short circuit thru the armature. I'd apply flashing voltage for at least 5 seconds and perhaps as much as 10 to repolarize the winding cores.

 

[Burnt Glove]

Duane, I will give it a try when I get back in the shop on Tuesday. Hopefully this will help straighten out the high exciter voltage as well.

 

[Insaneride]

My Black Face was backwards for a while. Didnt notice at first . I tried a 12v cordless drill battery. Didnt work. I got polarity correct after using a big 36 volt battery. Your gonna need at least an automotive battery or one of those tractor batteries or both in series IMO.

What Im wondering is why did it reverse polarity? Im thinking from being flashed backwards or from a hot shot start up back wards.

Why is the hi OCV's a problem? I thought the 90 some odd volts max was a spec for safety from factory Maybee the older machines had hi OCV's and no AUX I dont know but Im thinking above 90 volts becomes slightly lethal if careless but otherwise ok.

Interesting how these generators have no magnets and rely on residual magnetism (flashed) to generate.

 

[duaneb55]

My Black Face was backwards for a while. Didnt notice at first . I tried a 12v cordless drill battery. Didnt work. I got polarity correct after using a big 36 volt battery. Your gonna need at least an automotive battery or one of those tractor batteries or both in series IMO.

I have a setup using a 115VAC plug/cord and bridge rectifier off shop power that I've used to "pre-flash" an exciter in the process of installing the coils and before installing the exciter armature or even starting the unit. Wakes right up.

What Im wondering is why did it reverse polarity? Im thinking from being flashed backwards or from a hot shot start up back wards.

Coil cores may have been swapped when reinstalled.

Interesting how these generators have no magnets and rely on residual magnetism (flashed) to generate.

And it doesn't take a real strong residual magnetism either to kick things off. My personal machine - as well as others I've worked on - have been apart and/or sitting for years and woke up on first startup without flashing.

 

[Burnt Glove]

My Black Face was backwards for a while. Didnt notice at first . I tried a 12v cordless drill battery. Didnt work. I got polarity correct after using a big 36 volt battery. Your gonna need at least an automotive battery or one of those tractor batteries or both in series IMO.

What Im wondering is why did it reverse polarity? Im thinking from being flashed backwards or from a hot shot start up back wards.

Why is the hi OCV's a problem? I thought the 90 some odd volts max was a spec for safety from factory Maybee the older machines had hi OCV's and no AUX I dont know but Im thinking above 90 volts becomes slightly lethal if careless but otherwise ok.

Interesting how these generators have no magnets and rely on residual magnetism (flashed) to generate.

IR,

The problem I am having is high exciter voltage. When the machine is set to its lowest setting (100), and my rheostat is set almost to its lowest setting, it will burn a 1/8" rod of 7018 with no problems. In fact it's a little on the warm side. If I set the machine all the way to its lowest settings I can burn a hole right through a piece of 3/16" plate with an 1/8" 6010 rod.
The main generator volts are in spec. In fact they are on the low side of the spec.

 

[duaneb55]

Get your exciter polarity correct and see what happens.

I've never tested a unit to see how reversed exciter polarity affects exciter output voltage but as output is affected by brush location in relationship to the field coils (timing if you will), I suspect reversing polarity will have a definite affect on output voltage.

I also suspect this is why you're experiencing arcing at the main armature brushes for the same reason. Everything is functioning backwards.

If machine polarity is backwards at the weld output terminals and you're setup for electrode positive, you're actually attempting to weld as straight (EN) polarity which will affect weld performance.

 

[12V71]

I think you nailed it Duane. A friend of mine somehow (nobody has an answer) ended up with reversed polarity on his "81 SA200, He never checked the volts, but said it ran 6010 hot as all getout. and he thought his 9" grinder was going to explode.

 

[duaneb55]

It's the most logical thing that comes to mind for me at the moment 12V71 based in what has been described.

 

[Burnt Glove]

It's the most logical thing that comes to mind for me at the moment 12V71 based in what has been described.

This machine was wired backwards at the main brushes. Instead of the cable connections being at the 2 lower main brushes they where at the top. I figured that part out after I was given a wiring diagram from Brad @ Lincoln. After following the wiring diagram I also found the rheostat was wired backwards as well.
When I originally got this machine I made sure I marked all the wires with colored phone wire to insure proper connections when I put it all back together. I have learned that someone else has been inside this machine before me.
Honestly I think after I flash the exciter and get that straightened out everything will start to fall into place.