Frustrated to no end need help for 200 and 250
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  1. #1
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    Jun 2012
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    Frustrated to no end need help for 200 and 250

    Ok so I bought a sa 200 a while back running and welding. It had some issues here and there like head gasket, plugs wires carb needed rebuilt etc. fixed all of that. So I decide to go ahead and sell it and all of the sudden the thing won't weld for crap. It's breaking the arc bad. Anywhere from every second to every half a rod. If I turn it up hot hot it seems fine. But anything lower than about 50 on fine control it's terrible. I've got it in 4th and 5th gear...same problem.

    So I cleaned the gear selector, stud posts, and rheostat with 400 grit sandpaper. No change. Made sure leads where in good order and they are. Brushes are free and move easy and commutator is clean.

    Started thinking ocvs. Checked it and it was running about 97-98 cold on high idle. So obviously too high. Turned her down to around 89 and welded worse than before. I can barely keep the thing lit. Got new rods so not that either. Turned her up to 93 max and same result. Another weird thing is its showing a negative reading from the posts. Tried switching polarity and didn't really change anything. I'm at a loss.

    So maybe rheostat? My 250 diesel was doing the same...changed rheostat and it welds great. Which brings me to my next issue....checked the ocvs on it and its reading 108!
    And on top of that its showing a positive reading where as the 200 shows negative. I'm afraid to even mess with 250 at this point but surely 108 is way to high and could damage the armature right?

    Am i missing something here?

    Any help would be awesome. I'm out of options except changing rheostat but the one on the 200 seems to be in good order so hate to start changing good parts.

  2. #2
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    Re: Frustrated to no end need help for 200 and 250

    Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.
    -Cree Indian Proverb

    SA 200 Lincoln
    Victor Torches

  3. #3
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    Re: Frustrated to no end need help for 200 and 250

    Thanks that is helpful with some of my questions. I went out again and played with it for a bit. Adjusted ocvs back up to 98 and its welding better. But I know this range isn't specified as safe. I still don't think it should break arc with a 6010 below 40. Yet it doesn't do this with a 7018 below 40. I long arced the 7018 just to see if I could make it break and it wouldnt break.To me the thing should weld as long as its got the heat it needs. Regardless of the rod used.

    I'm still really confused on why it would read negative on the voltmeter from the studs. My 250 reads positive as it should.

  4. #4
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    Re: Frustrated to no end need help for 200 and 250

    For the correct polarity try flashing your field.

    Flashing the exciter field consists of passing current through the fields using an external source of 6 to 125 volts of DC power from a storage battery or DC generator. If using a DC generator, keep the generator turned off except when actually applying the flashing current. To flash the fields:
    Turn the welder off. Raise one exciter brush off the commutator. On Lincoln welders, attach the positive lead from the external DC source to the right hand brushholder. Carefully holding an insulated section of the negative lead from the DC source, touch its lug or clamp to the left hand brushholder for five seconds. Pull it away quickly to minimize arcing. Remove the lead from the right hand brushholder, replace the brush on the commutator, start the welder and the generator voltage should build up.
    Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.
    -Cree Indian Proverb

    SA 200 Lincoln
    Victor Torches

  5. #5
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    Re: Frustrated to no end need help for 200 and 250

    Thanks gg

    So if I understand what your saying I need to do this to the brush holders coming from the cone out of the front. And use my 250 to do so. Any particular setting I need to use from the 250? And do you think this might change some of the welding issues?

  6. #6
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    Re: Frustrated to no end need help for 200 and 250

    Personally, I use a 12v battery. If done correctly it should give you a positive vs. a negative. Done backwards, wrong brush, will be negative. I don't know why they swap polarity, but I have had it done on machines (SA200s) before. Yes, the exciter brushes is where this is done.
    You do know that 6010 is supposed to be welded DCEN, as is 7018. I'm not sure how you're checking whether it's neg. or pos. on your machines, but sounds like to me the 250 is the one with the wrong polarity.
    As for the arc breaking, look at the brushes & brush holders on the exciter. Hard, chirping brushes or weak brush springs could either one be the cause of that.
    Last edited by gizzardgutz; 07-22-2013 at 08:21 PM.
    Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.
    -Cree Indian Proverb

    SA 200 Lincoln
    Victor Torches

  7. #7
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    Re: Frustrated to no end need help for 200 and 250

    Yes sir I do know that. That's where i can't figure it out. My 250 will burn 6010 7010 and 80s with the best of them. I know also you can even hear the difference in the two as well as see it. The way I'm checking the ocv is with my positive voltmeter on the positive stud and negative on the negative. With the machines at high idle.

  8. #8
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    Re: Frustrated to no end need help for 200 and 250

    Quote Originally Posted by gizzardgutz View Post
    You do know that 6010 is supposed to be welded DCEN, as is 7018.
    I think your finger slipped - should be DCEP

    Dave J.
    Dave J.

    Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~

    Airco 300
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  9. #9
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    Re: Frustrated to no end need help for 200 and 250

    Now I feel stupid lol. Been too long since I learned about all of this. Looking back not even a year ago i was welding some sheet metal with dc- to help prevent burn through. Think I had dc- confused with ac. None the less...it should weld better then if I can get it swapped right?

  10. #10
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    Re: Frustrated to no end need help for 200 and 250

    I never tried 7018 the "wrong" way, not sure what the difference would be - but I'm sure DCEP would weld better

    Dave J.
    Dave J.

    Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~

    Airco 300
    Dialarc 250 AC/DC
    Invertec v250-s
    Maxstar 150s
    SA200
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    Dirty ugly tools - perfect

  11. #11
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    Re: Frustrated to no end need help for 200 and 250

    Ok we'll thanks both of you guys. Gonna try it first thing tomorrow to see what happens.

  12. #12
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    Re: Frustrated to no end need help for 200 and 250

    Quote Originally Posted by MinnesotaDave View Post
    I think your finger slipped - should be DCEP

    Dave J.
    My finger didn't slip, virtually all of my SA200s were DCEN & as many times as I've been corrected it stays stuck in my head that that it is correct.
    But, you are right. As I stated above, my machines had the polarity wrong apparently, because I welded with several machine that way for years.
    Last edited by gizzardgutz; 07-23-2013 at 03:15 AM.
    Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.
    -Cree Indian Proverb

    SA 200 Lincoln
    Victor Torches

  13. #13
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    Re: Frustrated to no end need help for 200 and 250

    Quote Originally Posted by gizzardgutz View Post
    My finger didn't slip, virtually all of my SA200s were DCEN & as many times as I've been corrected it stays stuck in my head that that it is correct.
    But, you are right. As I stated above, my machines had the polarity wrong apparently, because I welded with several machine that way for years.
    I'm not sure what you are saying.

    7018 and 6010 rods are listed to run DCEP.

    Dave J.
    Dave J.

    Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~

    Airco 300
    Dialarc 250 AC/DC
    Invertec v250-s
    Maxstar 150s
    SA200
    Spectrum 700 plasma
    MM210
    Dirty ugly tools - perfect

  14. #14
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    Re: Frustrated to no end need help for 200 and 250

    To clarify, I ran all of my SA200s with the electrode negative. I welded with them for many, many years in several settings, pipe, structural, oilfield, construction, onshore & offshore. Many welding tests & a work environment with engineers & inspectors wasn't a daily thing, but they were there for some time on most projects. I was never called for this discrepancy (DCEN) therefore I've come to the conclusion that the polarity was backwards on my machines. I didn't know it was even possible until I joined this forum several years ago & was called numerous times for remarking I used DCEN for 6010 & 7018.
    Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.
    -Cree Indian Proverb

    SA 200 Lincoln
    Victor Torches

  15. #15
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    Re: Frustrated to no end need help for 200 and 250

    Ah I see - thank you for the clarification.

    Having some machines with the polarity reversed, and some not, could get confusing...

    Dave J.
    Dave J.

    Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~

    Airco 300
    Dialarc 250 AC/DC
    Invertec v250-s
    Maxstar 150s
    SA200
    Spectrum 700 plasma
    MM210
    Dirty ugly tools - perfect

  16. #16
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    Re: Frustrated to no end need help for 200 and 250

    A quick check on lincoln for electrode polarity shows that 6010,7010 are DC+ or DC- ,+ being prefered, 7018 is listed as DC+ or AC.

    So IF you learned to be proficient with a particular machine/machines not knowing what the actual polarity of the machine was, so be it.

    But that then raises the question as to how to check what the actual polarity of your welder is.

    DC current flows from NEG to POS. So you either you need a good old fashoned analog voltage meter or a fangled new digital gauge that will tell you if your leads are reveresed.

    First if the meter you are using has removable leads verify that the red lead is in the POS socket and the black lead is in the NEG socket. If its a multi meter set it to DCV in the 100V range.
    With the welder running, put the Neg (black) lead on the Neg output terminal and the Pos (red) lead on the Pos output terminal.
    The Analog gauge will give you a voltage reading if the polarity is correct. If the needle is trying to read below zero and bouncing off the pin then the polarity is reversed.
    If you are using the fangled new digital meter read the manual to now what it is telling you..or maybe the screen is telling you anyway.

    Now I have another thing to do this weekend on my day off.
    14 SA200's from 1936 to 1973
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  17. #17
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    Re: Frustrated to no end need help for 200 and 250

    I found this thread researching "flashing" but I thought of it again when I learned something new yesterday:

    Got my new-to-me 1947 SA200 running yesterday. It's a crank start that had been abandoned for many years. I'm too old to crank and crank and crank trying to bring one back to life, so I hooked the weld outputs to my Miller EconTwin on DC and was able to roll it over quite smartly. I put a fair amount of oil in the spark plug holes to pre lube the cylinders and then rolled it for several minutes with the plugs out. Then when I had everything else ready, it actually fired up pretty easily.

    Anyhow, after I got it running I checked the outputs of the exciter and the weld generator. At idle, the exciter is putting out 114 Volts and the OCV on the weld generator at the minimum setting is about 65 volts. But the polarity on both was backwards!

    I had assumed that the direction the generator turned the engine would depend on polarity and supposed that I must have guessed right the first time since it rolled the right way. But I reversed the leads and started it and guess what...it still rolls the right way, but now the outputs of both the exciter and the weld generator are correct. Got to thinking about it and it made sense; the rotation of the generator when used as a starter motor is going to be the same with either polarity because the two cancel out. But the output when welding is going to depend on the exciter's polarity.

    So I'm betting that gizzard's experience with several SA200's putting out wrong polarity stemmed from starting them off other SA200's as I understand is common practice on "firing lines" but I have no experience there, just guessing...anybody know more about it?

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