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79 sa200 won't strike an arc

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Dano's pro welding

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Discussion starter · #1 ·
I have a 79 Lincoln sa200 it sat in the back of a truck 2 years I put new gas cleaned the carb and it runs smooth as could be but when I strike an arc all it does it a little spark I cleaned the commutator with a stone and still nothing an I only have 4 volts to the plug I also have no power to the auto idle switch or to the solenoid any help would be appreciated ty

Dan
 
#2 ·
The exciter has lost it's excite somewhere on here is a post on the proper procedure for reexciting im not sure how it has some thing to do with putting an outside power source to the exciter armeture
 
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#3 ·
Sitting that long it probably needs the exciter flashed. To do so, momentarily apply 12VDC (+) to the right brush lead and (-) to the left.

The no power to the idler switch or solenoid could be a bad oil pressure switch.
 
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#4 ·
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:
1. Turn the welder off. Raise one exciter brush off the commutator.
2. On Lincoln welders, attach the positive lead from the external DC source to the right hand brushholder.
3. 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.
 
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Discussion starter · #5 ·
Yeah I heard about that I took it to the only guy in town he wanted $1600 to do it for me I just didn't know if it could be a wire or something all the wires are dry rotted I was going to re wire it tomorrow put a new switch and solenoid
 
#7 ·
24V batery is fine but I'm not following your switch idea.

Flashing isn't something that needs to be done everytime you use the machine. It's just that residual exciter magnetism can go away if not used for an extended period of time. i just put a unit back together that has been sitting for over a couple years but surprisingly it woke up without flashing even though I was expecting I would have to. The next one might be a different story.
 
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#9 ·
Yes. The reason the manual instructs to do so while the unit is off is so the 115 +/- exciter voltage doesn't backffeed into the flashing battery as soon as output starts if the engine were running and the flashing leads were held to the brushes too long. It can be done with the unit running but it's usually just a quick one second flash to get things going.

On the idler switch, it provides power to the control board (and with some units the idler solenoid) but the switch gets power from the oil pressure switch (usually 7psi setting) once oil pressure builds. So, if no power to the idler switch, the OP switch is the place to start.
 
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#11 ·
Duane is there a way to reverse the polarity of the machine? i know i can switch the leads but would like to reverse the leads so they are accurate to the lugs
 
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Discussion starter · #15 ·
Ok well I flashed it again I now have the same volts as before but now I have no spark at the brushes I replaced the pc board the oil switch the solenoid and almost all the wires I'm guessing it has a bigger problem like a messed up coil or something is shorted out I'll prolly try to find a used generator and replace it tired of messing with it and need to get back to work
 
#17 · (Edited)
(I would)
Use an adapter to connect an incandescent light bulb to the auxiliary power receptacle. Then, flash the exciter while the machine's running and watch for the lamp to pick up brightness as an indication that exciter voltage is on the climb. Sometimes "buildup' takes repeated flashing and some run time.

FWIW, The replaced parts described in reply #15 would be irrelevant to getting basic exciter function.

Good Luck
 
#20 ·
Dano's pro welding said:
Yeah well I replaced the oil switch cuz it was always open and the pc board had prongs broke I true re soldering them but went ahead and replaced it and the solenoid the wires were fried
Click to expand...
I'm not questioning that the common wear items needed replacement.
I just thought it'd be good to clarify to other readers that the replaced parts have nothing to do with exciter voltage hunt.

Good Luck
 
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duaneb55
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