Lincoln SP-135T feed problem

I have a new Lincoln SP-135T that does not want to feed wire anymore.
Today I loaded the supplied spool of wire (Lincoln L-56, .025), feed
the wire till it came out of the gun, installed the tip (.025) and
nozzle then connected the shield gas setup. Everything was going great
until I started welding.

After about an inch bead the wire stopped feeding. I was just putting
down a bead on some flat steel stock. The wire was still poking out
of the tip about 1/8 inch. I opened the side panel not knowing what to
expect but nothing looked out of place. I pulled the trigger a couple
of times and the feed roll moved very little, I tried this over the
entire range of feed speeds and the feed roll never moved more that a
degree or two.

I released the spring loaded pressure arm and was able to push the
wire by hand through the gun with minimal force. Note that there is
almost no pressure on the wire spool, I'll tighten this up a bit when
I get the feed issue taken care of. I also checked to make sure I was
using the proper groove in the feed roll.
With no pressure on the drive roll I pulled the trigger and the drive
roll rotated in jerks. What's up with that? After alot of looking
around I decided to remove the drive roll. With the drive roll removed
I pulled the trigger and the drive roll shaft rotated like a champ. I
tried this at different speeds and the drive motor seems to work. I
reinstalled the drive roll and were back to jerky rotation. After
looking around some more I slipped some paper between the drive roll
and the wire , note this is with no pressure on the drive roll, and
the drive roll rotates just fine. It seems that the drive motor will
not work if the wire is touching the drive roll.
I'm out of ideas on this one. Any thoughts on this issue problem would
be appreciated.
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Feed-speed control checked; probably not the problem Cable and gun checked; probably not the problem Wire spool tension low; backlash possible but not the problem Jerky motion of drive roll; drive motor will not work if the wire is touching the drive roll.
Suggest that spring pressure is too great on the drive roll, causing motor shaft to bind.
The spring pressure should be LOW enough so that if the wire jams in the contact tip, the wire will slip in the drive roll and avoid bird-nesting between the drive roll and the entry into the cable.
Recommendation: - Rewind all the wire onto the feed spool and secure to avoid unwinding. Remove feed spool from the machine. Remove contact tip. - Ensure wire entry to drive roll area is clean. - Close the pressure arm and reduce spring pressure to minimum. - Pull trigger to verify correct feed operation of drive roll. - Replace feed roll and re-thread wire through drive roll, cable and gun. - Pull trigger to verify that wire is driven and drive roll runs smoothly (no jerkiness in motion). - If the jerkiness persists in the drive roll, motor or drive roll bearings may be damaged. - If the wire does not move, increase the spring pressure slightly. You should be able to hold the gun against a hard surface (not a body part) to prevent the wire from exiting the gun and the wire should slip in the drive roll without bunching-up inside the machine (bird nesting).
Once the feeding is smooth, replace the contact tip and resume welding.
Reply to
Thomas Kendrick
A wild a$$ guess would be that somehow the welding voltage is getting fed back into the drive motor for the wire... I believe, if looked at closely, you will find insulating plates, washers, etc., to provide the isolation needed. Maybe something shifted, got loose or whatever. I would check both the spool side and remove the cover to check the "back side" where the drive motor is located. HTH Ken.
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Ken Sterling
You have a guarantee. I would load it up and take it to the service center. They will fix it, or let you know what the problem is. If you work on it, you could void your warranty if it is something internally wrong with it, and not something simple.
You paid good money for it. It should work right.
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Sorry..... I overlooked the word "new".... sigh.... Ken.
Reply to
Ken Sterling
I was at the Delco Drags last October here in Las Vegas. I was at the Lincoln semi trailer hammering for a good price on a Square Wave 175. I told the tekkie that I had a SP175+ wirefeed that had a defective trigger or contact. Sometimes it just wouldn't feed until I opened up the hatch and wiggled the wires.
In a deep Carolina mountain drawl, he said, "Well, dang, buddy. Ya got a three year guarantee. Take the durn thing to the Repair Center, and get it fixed for free."
I still have to wiggle the wires once in a while. Maybe one of these days I will take it to the durn Repair Center before three years passes.
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make sure the reversible dual groove wire drive roller is set for .025" wire and not .030" wire. That might make the wire slip like that. just an idea. walt
Reply to
Thanks for the responses.
I contacted Lincoln and they referred me to a local rep. Turns out it was a problem with the feed control board. I did not receive any specifics on what the problem was.
Thanks again, Jesse
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The repair shop probably doesn't know. Present practice in electronics repair is to swap boards until it works - depending on symptoms, they might at least know which boards to swap, otherwise they tend to start with the ones that most commonly fail and keep going until it works.
Under warrantee it's not so bad, but when the warrantee runs out, any 10 cent component will cost you $500 for the board it is on. Finding the 10 cent component is not easy - certainly the Lincoln diagrams I have seen only document connections off the circuit boards, and the coatings which help make the boards more resistant to the envrionment would also make them hard to repair. The upside for the company is that their service technicians need less training and equipment and can do most repairs faster than if they had to figure out components. In addition, you're more likely to buy a new welder when you're faced with a $500 board or $1000 for a new welder in 5 or 10 years.
Be sure to use it enough to have any "infant mortality" failures occur and get repaired while it's still under warrantee. Then hope that the old-age failures stay away long enough for the thing to be worth what you paid for it. Some places routinely sell them off when they hit end of warrantee.
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