WeldingWeb Journeyman
I have a 1977 blackface. I'm having to roll the rack like every 7 to ten hours of use. I set it at 92-93 ocv's. after lunch sometime it jumps down to 65 ish ocv's. I cleaned the commutators a few times already with the stone. the only way i can seem to get it past 70 volts is to roll the rack. Any one know what might be going on? My guess. is the brushes might be stuck or one of my coils is failing. but I really don't know. thats just a guess.
WeldingWeb Foreman
This must be one of the green light SA200 with the aluminum(copper clad aluminum) shunt coils. You will need to replace them with solid copper shunt coils.
This had been discussed before.
https://weldingweb.com/vbb/showthrea...s+copper+coils
Last edited by guajilloweld03; 05-01-2020 at 06:03 PM.
WeldingWeb Foreman
Like guajilloweld03 said, the shunt coils could be on there way out but, I would check the shunt coils with a ohm meter, you should get around 41 ohm + or - 10 %. Also check all the wires and connections for bad contact. Check the Rheostat for good contact with an ohm meter to see if the number of increments go up and down on the scale smoothly, the ceramic could have a crack in it, and when it gets hot it expands making it loose contact also. Use some 320 grit sandpaper to clean up the surface where the wiper brush contacts the back of the Rheostat to. Also, I would put the rack back to the factory spot marks, that way you can get a better Idea of what might be going on. These are just a few things I could think of before doing a major tear down.
SA 200s : 1944 1945 1963 1965 1969
1981 SA 250 D3.152 DC only
2004 Ranger 10,000
Lincoln Pro Mig 135
Miller Load Bank
Hobart GPB 258 Pipeliner
Hobart GPB 261 Mainliner
Hobart Airforce 250
Everlast PA 200st
WeldingWeb Journeyman
Where can you find the factory marks? its pretty rusty around the rack. And i cleaned up as much as I could With a 60 grit sanding disk I pulled off my grinder. It got everything up a bit but the only way I was able to get it up to 93 volts was to roll the rack. before cleaning it was like 40 volts. after cleaning the commutators it went up to like 50. after cleaning everything else it was like 65. After that I had to roll the rack. Now it feels like I'm constantly rolling that thing when ever I go to use it. I'll try to check the other stuff you described with an ohm meter. I'm not skilled at that sorta stuff though.
WeldingWeb Foreman
https://weldingweb.com/vbb/showthrea...t=Rolling+rack
Read this post on discussion on rolling the rack.
#37 has pic of rack marks
Removing generator does not look that hard. But like most things the first time doing a job there is usually a learning curve. Have never done this job, but I know some times first time jobs can be a challenge but possible.
Last edited by guajilloweld03; 05-02-2020 at 02:49 PM.
WeldingWeb Journeyman
Well I didn't put the rack back to stock yet unless that happened by chance. but testing everything with an ohm meter has me believe my left side exciter coil has failed on me. when I pulled the left side brush out and stuck it with the ohm meter and put the other one on the right side wires i got 117 ohms. when i pulled the bottom center wire out and stuck each brush individually i got 1 ohm on the left side and 112 or so on the right. so I ordered copper coils online. the rheostat went from .5 when set to 100 to like 65 or something when on the low side.
WeldingWeb Foreman
Im glad you found that post, I had forgotten all about it. Duane is the go to man on these SA machines.Originally Posted by guajilloweld03
SA 200s : 1944 1945 1963 1965 1969
1981 SA 250 D3.152 DC only
2004 Ranger 10,000
Lincoln Pro Mig 135
Miller Load Bank
Hobart GPB 258 Pipeliner
Hobart GPB 261 Mainliner
Hobart Airforce 250
Everlast PA 200st
WeldingWeb Foreman
Sounds like the Rheostat is working fine. In the SA 200 service manual, the solid (hard wires) ohm .276 to .296 , and the Fine strand wires ohm 127.0 to 133.0 , this would tell you which side has gone bad.
I remember one time I had mixed up the the white wire (-) with the Black wire (+) with the brushes and also had low voltage at the outlet plug and low welding output.
SA 200s : 1944 1945 1963 1965 1969
1981 SA 250 D3.152 DC only
2004 Ranger 10,000
Lincoln Pro Mig 135
Miller Load Bank
Hobart GPB 258 Pipeliner
Hobart GPB 261 Mainliner
Hobart Airforce 250
Everlast PA 200st
WeldingWeb Artisan
Code 7789 had the most problems with shunt field coils and I believe were around 1977. 7307 is also known to have more problems. Lincoln has warnings not to roll the rack too much.
WeldingWeb Journeyman
This thing is a 7789 if the markings are correct. Now that I know something is a problem I think Im switching back to the old hobart stickmate to finish up the remaining 70 staircases I got left to do. Or at least use it till I can get this Sa back and running. It could also use a new carb and engine rebuild as well I think. Its been running low on oil almost before it runs out of gas. and the oil is all over the door when I leave it up so I know where it's going at least. I thought about selling it for a Ranger or Eagle but I kinda like this old thing. especially the way it welds when its running correctly.
WeldingWeb Foreman
Most repair guys are probably looking for work as a lot of oil field work has come to a stop. Some repair guy should be able to fix quickly.
WeldingWeb Journeyman
Are there any good ones around the Columbus Ohio area? I took it to some guy who repairs alot of stuff for the amish up here where I'm at but he said the engine would take him a few weeks. so I think he's just gonna be doing the electrical part of it for now if he can figure it out. As for the witness marks on the brush rack I looked all over and saw nothing that would indicate the alignment of it. I see what it might look like from the other post but I did not see anything like that on my machine.
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