View Full Version : Hobart G-250 after striking arc loses spark.
06-24-2009, 08:24 PM
I have a Hobart G-250, Jeep CJ2-A engine, Willies BSBI, "Inline four cylinder flathead" Specs 4940 It runs good. After striking an arc the engine revs up but shortly after that while welding I lose the arc and have to scratch the rod to get it back. Makes welding kind of hard. Does anyone know what is causing this?
06-25-2009, 08:07 AM
I have a 251 that I think are practically identical units.
Does the engine rpm drop when you lose the arc or is it still running up on the governed setting? That would be an idle control problem.
A couple other areas to check is the fine rheostat to be sure its clean with no electrical resistance throughout the range.
You can put a vom on the rheostat and check for resistance with the unit off or you can put a dc volt meter on the cable lugs & check the dc volts when you spin the dial with the unit running.
Likewise the amp control wheel needs to be clean inside with no resistance throughout the range. If the amp wheel is stiff & hard to turn, corrosion may be breaking the circuit inside.
I'd enjoy seeing a few pictures.
Best of luck -doug
06-25-2009, 07:49 PM
I've had one since '86 so I'll pass on some of the things I've learned.
1- Pull the end cover off the generator and check that all the brushes are free and clean and spray the cummutater with a good electrical contact cleaner(mice love to set up house in here even when you run it all the time)
2- Check the wires where they plug into the polarity switch and the 110 v outlet for clean and tight.(also make sure that the outlet works on both sides)
3- As mentioned check the fine and course controls for connections and clean(another good place for electrical contact cleaner and generally look over all wiring. HTH Bill
06-26-2009, 09:01 AM
I've had one since '86 - HTH Bill
Howdy neighbor!! I'm up on the North Shore of Oneida Lake so we're pretty close I think.
It's nice to meet you online Bill.
A little off topic, but how about sending me a few pictures of your old Hobart, I enjoy looking at the differences & similarities & also can get a few new ideas from looking at pictures.
Please send to firstname.lastname@example.org
I've had my 261 for better than 20 years too, mine was sold new in 1956 to a company near Niagara Falls, NY.
Also I'm just finishing up another old machine I bought in early spring over in Lakeport that was sold new in 1950 to a co. in Rochester, NY.
You can see pictures if the 5CW Click here (http://www.cnyara.com/welders/Hobart-5CW/index.html)
take care - doug
06-27-2009, 12:35 AM
I looked at the rheostat it seemed to be making contact. The propellant ran out of my contact cleaner. I noticed a slot on each side of the amp control wheel behind panel so I sprayed some oil in them while turning the wheel, the wheel turns easier and makes a click at the stops now. After waiting a day and a half for the oil to run out I tried it and it is welding good now. I am still going to check the brushes. Thanks Doug & Bill for the info, Dave
06-27-2009, 08:14 AM
Be gentle when inspecting the brushes, especially if they seem to be stuck in the holders, the old brushes will crumble & disintegrate if you use any force on them.
Free up each brush so it slides easily in its holder & lube all the brush spring pivots like Bill mentioned.
depending on how much of a build up is on the commutators it may take more than spraying contact cleaner to clean the surface up.
If the surface is really glazed & cruddy cleaning with very fine sanding sponges (not emery) works nicely.
What works best for me is to take each brush and wedge it up higher in the holder using the spring to hold the brush away from the armature surface while you're working and with all the brushes held up and not making contact.
Double the sanding sponge over the end of the stick overlapping a few inches and put a few staples in it up away from the end.
The sponge will conform perfectly to the commutator with very little pressure needed, don't press hard enough to feel the end of the stick, you only want to feel the softness of the sponge conforming to the surface.
Replace the sponge often and polish it up with finer grit a few times and wash it all out with a good electrical cleaner and you should have a nice clean surface.
I actually run the unit on low idle while gently cleaning with a piece of the sanding sponge attached to a paint stick, but that's up to you. If you do it while running, the spinning armature should be pulling the sponge away from you not pushing it to you and you only need a very slight touch, you're not grinding..only polishing.
The brushes can also be de-glazed if they look like they need it.
Do one brush at a time with the unit off, cut a long strip of 500grit or finer sand paper (not emery) a little wider than the brush and as long as possible.
Slide the paper in between the brush & the armature with the grit side facing the brush , then a little sea-saw of the paper while keeping it wrapped tight on the armature will clean up each brush.
it only takes a few strokes as the spring loaded brush material is very soft & easy to remove, be sure not to over do it.
After the brushes are run in 5 or 10 minutes under a load, look at each of the brushes when the unit is running at the governed speed under a load and you shouldn't have any noisy, squealing or arcing brushes.
And you also might want to get into the amp control if its really cruddy in there like mine were:
Heres a picture: click here (http://www.cnyara.com/hobart/GPB-261/images/IMG_0831.JPG) And here (http://www.cnyara.com/hobart/GPB-261/images/IMG_0837.JPG)
take care -doug