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.