I just purchased a Lincoln SA 200 Black Face (Octagon Generator) code 8023 welder to replace my Miller 251D that dropped a valve and ventilated a piston. The problem I'm experiencing is that it will not weld unless the Fine Current Adjustment is set on 100 or the machine is set to "Fast Idle". Lower settings on the Fine Current Adjustment bring about the "sparkle" and the engine won't go to fast idle. Auxiliary power works fine and will bring the machine to fast idle immediately as it should upon triggering a grinder. The machine has a new oil switch and green light as well as radiator and water pump. I used the technique mentioned in #21 Here: http://weldingweb.com/showthread.php?446361-SA-200-Blackface-Revival to check the field shunt coils and found the requisite 45 OHMS. Upon inspection of the rheostat, the brush on the rheostat wiper arm appears relatively thin as the metal arm is within 1/16" or less from the rheostat coils. I cleaned them as much as possible and checked the OHMS and found the range to be 0-64 as required with the blue wire removed. I have not checked any brushes for ease of movement but did remove about a gallon or more of pecan shells and leaves out of the generator housing. The wiring looked to be intact. My question is though the rheostat OMS out properly, would it still be possible for it to cause this situation (as it's the only thing that seems to make sense to me)? Since the machine DOES WELD, can it definitively be determined that the field shunt coil windings are OK? Am I doing any harm by simply welding with it as is?
TexasCowGrower
I have no way off verifying the low idle speed but it SOUNDS normal and it works properly when fine adjustment is set at 100 or auxiliary is used. It cycles properly in those instances. Wouldn't a faulty reed switch prevent proper idle management or welding regardless of fine adjustment setting?
Low idle should be 1000 rpm. If you don't have a hand tach, bump it a bit and see what happens.
Just the idle stop screw on the carb. Had it happen to me numerous times, quarter turn and its good to go again.
Good deal, I'll "git-r-done" first thing in the morning! One thing though...why is the low idle speed currently good enough to strike an arc at 90 amps with the rheostat set at 100, but too slow to strike an arc set at 20 in the 80-130 amp setting? Is it because of the demands of the different arc characteristics with regard to these settings?
Ok...I had to turn the idle screw up 3/4 turn to get it to arc at 20 in second gear but the arc was really cold compared to my older machine. When I turn the rheostat up above 30 it seems to perform better. Before turning up the idle the lowest setting I could get an arc was 27. I'm using 3/32 7018 rods. I'm starting to suspect the rheostat is faulty or braking down below 30 despite the OHMs reading properly over the entire range. Am I wrong or do I need to look further at the brushes given that the machine sat long enough to become a rodent storage bin at some point?
I'd back up a step or two and clean the exciter and main armature commutators (320grit sand paper or commutator stone) and make sure the brushes are all free.
I was thinking of doing just that duaneb55 if for no other reason than to insure the arc quality given the rodent residency. I DID pull the rheostat out for inspection and noticed someone had cut the terminal on the low side of the rheostat off and thus installed the red wire on the opposite terminal than recommended in online pics I have seen. The ridges in the area of the 20 setting are somewhat flatter and worn compared to the rest of the unit. Not sure if this has any effect at all. Checked OHMs again and got a smooth progression from 67 OHMS on the low side to 0.3 OHMs on the high side (100 setting). These readings were taken from the lugs still remaining on the unit and NOT from the cut stub. When taken from the stub they are opposite. Might THIS be the culprit...or at least be a "player"?
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FIXED IT!!! :cool2: I drilled a hole in the cutoff tab in the above pic and moved the terminal back where it's supposed to be. Fired it up and it welded PERFECTLY!!! :cool2: Apparently it doesn't like to be wired BACKWARDS! I'm ecstatic! I was braced for the worst and it turned out MUCH differently. Now I'm perplexed as to WHY someone would perform such unnecessary surgery and when finished deem it a job well done... :dizzy: THANX ever SO MUCH to you guys for your help! This forum is PRICELESS!
Well what you had is the standard "from the factory" rheostat configuration. I can show several photos of installed and new rheostats that look just like yours as shown.
With it re-wired the way you've described it's actually now backwards and minimum output should be at 100 and maximum at 10.
For the record, the rheostat doesn't care if the red wire is on the outer (max) tab and the blue on the wiper or the other way around. However, the red is typically located and shown on the outer (max) for consistency in wiring.
With it re-wired the way you've described it's actually now backwards and minimum output should be at 100 and maximum at 10.
For the record, the rheostat doesn't care if the red wire is on the outer (max) tab and the blue on the wiper or the other way around. However, the red is typically located and shown on the outer (max) for consistency in wiring.
There's still a breeze in the air.
It welds fine even though backwards so just switch the red wire back to the original outer terminal and you should be good to go. Could be the rheostat windings were just dirty.
But I'd still clean the commutators as good maintenance practice.
It welds fine even though backwards so just switch the red wire back to the original outer terminal and you should be good to go. Could be the rheostat windings were just dirty.
But I'd still clean the commutators as good maintenance practice.
I just run some 320grit or finer sandpaper over them and the pads at each end and blow them off with compressed air.
You DA MAN duaneb55! I rewired the rheostat back to it's original configuration and spent the next hour and a half cleaning commutators and brushes. One pair of brushes on the main generator was frozen in place to the extent that I was afraid of damaging them getting them free. Fortunately I was able to get them out intact. I was then able to lower the idle speed 1/4 turn and still initiate high idle. I found the ocv voltage (in 3rd gear @ 100) to be 96 so I did NOT increase the high idle speed. It now will weld properly in 2nd gear @ 20 but seems to be a bit colder than my 251D. I'm not going to complain because I LOVE the pure simplicity of this machine, especially compared to the Lincoln 305G I was set to purchase when I found the SA 200. 
I definitely plan to order a complete set of brushes and a commutator stone. Once again THANX for your help and if you're ever up in College Station area I owe ya a cold one
I definitely plan to order a complete set of brushes and a commutator stone. Once again THANX for your help and if you're ever up in College Station area I owe ya a cold one
Well drop the main sail and run up the jib! :laugh:
You're just a volt a above max for your code# which could just be meter tolerance.
View attachment OCV and Other Specs.pdf
Don't forget, any machine is more than likely going to be slightly different from the next. However, on the same machine I would expect a "cold" result at 20 in second gear vs. 100 in first due to the 100 setting resulting in a higher arc voltage (wet puddle) at the same amperage as a 20 setting (fast freeze puddle) in second gear. All covered in the Lincoln Shield-Arc dual control description/instructions.
You're just a volt a above max for your code# which could just be meter tolerance.
View attachment OCV and Other Specs.pdf
Don't forget, any machine is more than likely going to be slightly different from the next. However, on the same machine I would expect a "cold" result at 20 in second gear vs. 100 in first due to the 100 setting resulting in a higher arc voltage (wet puddle) at the same amperage as a 20 setting (fast freeze puddle) in second gear. All covered in the Lincoln Shield-Arc dual control description/instructions.
UPDATE I got a complete set of brushes installed and found a tachometer to check rpms. I found that with the low idle rpms set at 1000 as per book it would not arc but would at 1100 with the new brushes installed. It was probably 1200 rpms with the old brushes. While talking with a Lincoln tech rep about the age of the machine I asked about the arc situation and was told that the machine should arc at 20 amps at 1000 rpms. Since mine doesn't do that he suggested I check the connections or function of the reed switch as this controls when the idle up occurs. I located the reed switch and discovered the rings that hold it in place were OFF of the cardboard and the switch had fallen almost completely out of the copper housing! I couldn't put the rings back on for fear of damaging the switch so I went full ******* and zip tied it in place. WORKS PERFECTLY NOW! ... This time I'm POSITIVE
I got a complete set of brushes installed and found a tachometer to check rpms. I found that with the low idle rpms set at 1000 as per book it would not arc but would at 1100 with the new brushes installed. It was probably 1200 rpms with the old brushes. While talking with a Lincoln tech rep about the age of the machine I asked about the arc situation and was told that the machine should arc at 20 amps at 1000 rpms. Since mine doesn't do that he suggested I check the connections or function of the reed switch as this controls when the idle up occurs. I located the reed switch and discovered the rings that hold it in place were OFF of the cardboard and the switch had fallen almost completely out of the copper housing! I couldn't put the rings back on for fear of damaging the switch so I went full ******* and zip tied it in place. WORKS PERFECTLY NOW! ... This time I'm POSITIVE -
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