lincoln sa300

[gamboa.xavier]

i have a lincoln sa300. im having trouble with my arc. it puts out little sparks but wont strike when i go to weld. i have checkd all my grounds, brushes and fuses. does anyone know of any other things that could be wrong with it... and are the brushes supposed to sit on the exciter freely or are they supposed to be tightened down. any suggestions are much appreciated.

[weldonwelding]

Did it sit for any length of time? And u say u checked your brushes... did you clean em?

[gamboa.xavier]

yes it has sat for 6 months and yes i have checked and cleaned... i have kind of come to the end of options knowing what to check...

[gamboa.xavier]

do u know how much play the exciter brushes are supposed to have

[weldonwelding]

I have a sa250 that sits for months at a time. So every time I use it It does the same thing. I am no tech, but I can usually get it going. I clean the brushes with 220 grit Emory cloth and then start the machine up to clean the armature where the brushes sit with either a wire brush or the same Emory cloth. This method may be dangerous or not the correct way but its worked for me every time

[weldonwelding]

do u know how much play the exciter brushes are supposed to have

No.. but I would bet cruizer knows. In fact he can probly tell you right off the back what the problem is. I usually space mine the same thickness as my Emory cloth

[gamboa.xavier]

ok thank you, i will try and find this cruizer

[duaneb55]

First - do NOT use emery cloth to clean an armature commutator as pieces of emery grit can get lodged in the brushes and tear up the commutator. This is pointed out in all Lincoln machine manuals. The best tool is a commutator stone and if you don't have one, silica sand paper can be used.

Also make sure the rheostat windings are clean where the wiper makes contact.

Is there 115VDC at the auxiliary power outlet? If both main and exciter brushes are free and main and exciter armature commutators are clean but no DC voltage at the auxiliary power outlet, the unit may have to be flashed due to loss of residual magnetism in the exciter.

SA machine manuals cover flashing but basically it simply involves momentarily connecting 6-12VDC to the exciter brushes - (+) to the right brush and (-) to the left. Without the unit running and following proper procedure requires lifting the right brush off the commutator and insulating with a piece of paper or other non-conducting material then touching the brush posts with the flashing power source leads for a couple seconds. Remove the insulating material and start the unit. If flashing was needed the unit should produce weld output (OCV at the weld output posts).