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Lincoln TIG not operating -- input please?

EndlessMtnFab

EndlessMtnFab

Well-known member
Joined
May 19, 2020
Member Number
100
Messages
267
Loc
Paxtonia, PA
Hey Guys,


Have a (slightly) older Lincoln Precision 375 TIG machine that decided it doesn't want to cooperate today. Just looking for input to see if I missed anything obvious before I fire the parts cannon or calling a service center ($$$ either way).

Fired up the machine, opened the gas valve, unwound the torch, foot pedal, and ground cable. Hooked it up and barely had an arc. Almost like trying to run a bead without the ground connected. You can just barely see the blue crackle at the tip of the tungsten. Cranked up the amps ... and I was able to lay 1/4" bead down and it hasn't worked since.

Things I have initially tried:

*clean ground surface on metal
*clean clamp surface
*move clamp to other locations


Confirmed switch was set to DCEN (DC Neg Polarity). Switched back & forth to DCEP & AC to see if the machine was hanging up somehow. Verified the remote switch was working (required for foot pedal). Adjusted the High Frequency knob and turned off. Scratch/Lift-off does not appear to be working either. Can see the little blue "spark" and nothing more.


If squeeze the pedal .... I can see the amperage climbing/falling on the digital gauge) as I vary how far I move the pedal. Confirmed gas flow, both by feeling the gas and verifying flow rate @ gauge.

The ground wire on this machine is 2/0 (two ought) wire. So I doubt it would just stop letting electricity flow through. Especially that it's un-damaged. The foot pedal was damaged about 13-14 years ago .... and I soldered/repaired the wires. I would like to ASSUME that the wiring repair is still fine. But what about the potentiometer in the pedal itself? That is confusing me --- is that pedal is clearly allowing the amperage to rise & fall ..... but the current is not "coming thru" the torch.


The torch itself is a C-K brand that I replaced all the consumable parts inside (making sure they were new & clean). The leads & water lines are un-damaged and have not been driven over, had stuff dropped on them, etc, etc.

And yes ..... Welder ran when last parked. :flipoff2:


What does IBB have for suggestions to further trouble shoot the issue? I can easily head outside to try any suggestions or check any specifics.

All help and comments are appreciated !
 
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ThePanzerFuhrer said:
You getting the correct input voltage from the wall?
Click to expand...


As far as I know ..... machine has been working there for the last 5 years with no issues. I did reset the breaker, as I thought maybe I had a partial trip (1 leg down) ---- but apparently, that's not the case. The other welder is working fine --- just not the one I want to use right now.
 
Do you have a spare torch cable to try?

Have you tried stick Welding with it to see if that works?
 
Twankie said:
Do you have a spare torch cable to try?

Have you tried stick Welding with it to see if that works?
Click to expand...
No spare torch That is/was a bit short-sighted on my part. :homer:
Haven't tried switching to stick yet. Actually ... don't even have a rod holder for it. Another dumb ass move on my part. Can probably hunt something down in the morning. :homer::homer:


I went thru the troubleshooting guide in the manual. 6 pages all literally saying the same thing " contact your local Lincoln Authorized Field Service Facility " :mad3::mad3: Why even have a fucking troubleshooting guide?

I did find out about something called "Spark Gap Adjustment " --- so I will be looking into that after dinner.


I know .... I'm a dumbass for not having a back up plan. Been dead reliable for years on end. Now it's just dead (temporarily).
 
EndlessMtnFab said:
As far as I know ..... machine has been working there for the last 5 years with no issues. I did reset the breaker, as I thought maybe I had a partial trip (1 leg down) ---- but apparently, that's not the case. The other welder is working fine --- just not the one I want to use right now.
Click to expand...
Holy shit, I remembered my password! 😂
Joe, check your voltage at the outlet using a multimeter, across each hot leg and the ground leg... Make sure your voltage is good. I've had my mig act up, only to find out one leg was at half its voltage... Turned out to be a bad receptacle...
 
total newb said:
Pull the cover and check the primary wires to the terminal block and at the trans/caps
Click to expand...
I'll head back and and look. Just adjusted the Gap Spec (much like points). Calls for .015 unless you don't use the Hi-Freq. Then it calls for .008. Mine was at .016. Didn't think it would do anything --- but adjusted it anyways. No change.

zukkev said:
Holy shit, I remembered my password! 😂
Joe, check your voltage at the outlet using a multimeter, across each hot leg and the ground leg... Make sure your voltage is good. I've had my mig act up, only to find out one leg was at half its voltage... Turned out to be a bad receptacle...
Click to expand...

I don't have a receptacle there. It is a direct wiring to the box. But I can easily pull the cover and verify the voltage to each leg.



At this point .... I'm beginning to think of 2 possibilities. The pedal and/or wiring has gone bad. Which is strange because the amperage still varies as you work the pedal (and the gas flows on/off like it should). The other possibility is the PCB (control board) may have taken a shit. I highly doubt it is the torch wiring, because I could still see the very faint blue "spark" working. When I remove the ground clamp --- there is nothing at all at the tip of the tungsten.
 
total newb said:
Pull the cover and check the primary wires to the terminal block and at the trans/caps
Click to expand...
zukkev said:
Joe, check your voltage at the outlet using a multimeter, across each hot leg and the ground leg... Make sure your voltage is good. I've had my mig act up, only to find out one leg was at half its voltage... Turned out to be a bad receptacle...
Click to expand...


Unbolted the panel. Checked the wires, blocks, and the caps. All clean (just a bit dusty). No corrosion. Nothing burnt. Nothing bulging or expanding.

Grabbed the multimeter and checked at the wall box. I'm getting readings between 241-249 volts (bouncing around a bit). Went back and checked the voltage at the blocks inside the welder itself. Same deal. 241-249 volts at the terminal blocks.

Tested at the torch one more time. Still the same results.


On a whim --- I checked out the cost of the wireless pedals. $800 plus. :eek::eek::eek::eek: Ain't got time or mownay foh dat !
 
Twankie said:
Since you have a meter out ohm the torch lead
Click to expand...
You didn't say "please" :flipoff2::flipoff2::flipoff2:


Schmoe is going to bed soon. Once he's tucked in .... I will go out and see if I can get some readings for you. Figure about 20-25 minutes (assuming no issues tonite with him).
 
Twankie said:
Since you have a meter out ohm the torch lead
Click to expand...

Just went out. It is a water cooled torch (which I already knew). There is no real way to access the wires on this particular torch head. Especially at the "business" end. The wires are inside the inbound/outbound water hoses and where they "split" is completely sealed. I didn't try to pursue it any further at the machine end of the torch leads. :frown:
 
Pull the handle down and it will expose the leads/hoses. The power one will have the threaded nut looking one, Atleast that’s how the every water cooled tig torch I’ve ever used is. Or just do it at the machine itself. Try unplugging the pedal completely and then scratch start. You can stick a welding rod in the torch and use that to stick weld with.
Wireless pedals are stupid expensive. If you need a new pedal, scc controls or something like that makes wired ones cheaper than Lincoln.
 
Scratch start the torch in stick mode. It may isolate the issue to the pedal
 
Brad said:
Pull the handle down and it will expose the leads/hoses. The power one will have the threaded nut looking one, Atleast that’s how the every water cooled tig torch I’ve ever used is. Or just do it at the machine itself. Try unplugging the pedal completely and then scratch start. You can stick a welding rod in the torch and use that to stick weld with.
Wireless pedals are stupid expensive. If you need a new pedal, scc controls or something like that makes wired ones cheaper than Lincoln.
Click to expand...
Brad, I did unscrew the handle and pull it down. I did see the locking nut there ... but I didn't go any further. Don't have the manual for the torch and wasn't sure if that was for the water or power.

At this point (9:30 here) .... I'm just going to wait until the morning and see what input I can find from one or two local stores. The local Airgas was listed as a repair center in the manual supplied with the welder. But when you head to Lincoln's service center page ... the nearest place is 1 hour away.

Did see wired pedals for 125-165 ----- which isn't horrible. I just didn't know the wireless ones were as valuable as my left nut. I just figured it would be one less thing to get damaged (as I did drop something on it many years ago and cut it in half). I was thinking the issue would be at the actual pedal.
 
EndlessMtnFab said:
Brad, I did unscrew the handle and pull it down. I did see the locking nut there ... but I didn't go any further. Don't have the manual for the torch and wasn't sure if that was for the water or power.

At this point (9:30 here) .... I'm just going to wait until the morning and see what input I can find from one or two local stores. The local Airgas was listed as a repair center in the manual supplied with the welder. But when you head to Lincoln's service center page ... the nearest place is 1 hour away.

Did see wired pedals for 125-165 ----- which isn't horrible. I just didn't know the wireless ones were as valuable as my left nut. I just figured it would be one less thing to get damaged (as I did drop something on it many years ago and cut it in half). I was thinking the issue would be at the actual pedal.
Click to expand...
Power cable will be the one with the threaded connection. The others are gas and water out. CK worldwide has fantastic customer service. My bet is it’s the pedal if it does stick or scratch start weld with it unplugged
 
Forgot I had to go take the recyclables to the end of the driveway (tomorrow is trash day). So I was out there and took another shot at it.

Unscrewed the foot pedal's 6 pin connector from the main unit. Flipped the switch from REMOTE (the pedal) to LOCAL. Raised the minimum amperage to make sure there was juice flowing thru. Connected the ground and tried a scratch/lift-off.

Not a damned fucking thing. :mad3: Not even that tiny blue spark that I was seeing when using the food pedal. The on-demand fan (for the electric motor) does work on start up & shut down. But (normally) goes silent until you're actually welding. Still doing that here ... so nothing has changed on that end of the spectrum.


Does this (more or less) remove the pedal assembly as being a cause? If so ... we're down to either the control board or the torch.


:shaking:
 
Only logical thing left at this point then, would be the control board. The welder is old enough that I wouldn't be shocked.

Price might shock me tho. :shocked:
 
Morning Update:

Borrowed a whip / rod holder and hooked it up to the machine. Switched over to STICK mode (DCEN) and everything fired right up. Proceeded to poorly weld/melt some 1/4 tubing I had laying outside. Fan came on as usual once the arc was struck/maintained.

Decided to switch to the foot pedal to eliminate that possibility. You can see the arc difference as you operate the pedal, so that takes the pedal out of the equation. :beer:

Switched back to TIG and tried to strike an arc with the torch. Nothing. I can't imagine that the "torch" part of the control board would fritz --- would have to be an entire board issue. Not something so specific. :confused: At this point ... going to chance it and fire the parts cannon for a new torch setup. Let's see how fast they can get me one. Will give them (2 guys) lunch money today for saving me a lot of time and nonsense (and money).

Input/comments are still appreciated. :grinpimp:
 
Afternoon update: (for anyone that gives a flying fuck at this point)

Shop contacted me after I sent them some pictures of the hose fittings (into the machine). They have a spare torch set that I can pick up tomorrow. They are suspicious of the board, despite testing fine with the stick welder. Apparently .... it is not unusual to have only half the board shit out (stick works TIG doesn't and vice versa). If the spare torches work, then a new torch set will be ordered. If the spares fail to strike an arc --- then I have to look into board replacement. Brad mentioned rebuilding the board vs replacing. Have to see how fast that can happen ... as I'm kind've in a tough spot here that I can't move the vehicle now. 😵

edit Oh yeah ... I forgot. Shop made me confirm the water cooler was pumping fluid and that the water was good. Yes to both. Apparently, if water gets gummed up or the pump stops .... it damages the wire itself, not the torch head (overheat).
 
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Don't have anything to suggest, but as an owner of an older TIG machine, I'm going to watch and learn.
 
Final Update:

The spare torch works fine. Welded for about 10 minutes on/off on different pieces. Zero issues. Contacted the welding supply .... he told me it was a spare that he no longer uses. 350 amp Weldcraft Torch with leather cable cover. $100. Sold !

He will also order me the new line/hose I need for my old torch. That way I can keep the smaller 250 torch for tight quarters. Might as well pick up some anti-freeze for the welder while I'm there. :beer:

Thank you everyone for your input !
 
Glad you found the problem, I was reading through thinking maybe you had an issue with the copper wire in the torch line degrading or breaking.

When I bought my Tig somebody had run it without the water line on and turned the wire into a lightsaber:eek: The wire in water cooled torches are not large enough to carry the required amperage without cooling but they are lighter and more flexible.
 
Getting there. :)

Looked on Amazon quickly .... new wire/hose combo looks to be about 50 bucks for a 25 footer. So add on another 822% for brick/mortar pricing. :lmao:

I was going to try coolant this time around, but will wait until I get my old torch back. The size difference between the 250 & 350 amp units is noticeable enough. All I've ever used for the last 17 years is distilled water .... but figured I would try the coolant this time around in case I dno't get the garage heater up & running fast enough.

Are there any coolant concentrates out there? or are they all pre-mix? No ... I'm not putting green or RV antifreeze in there. :flipoff2:
 
I’m extremely surprised. The power lead in that hose must be super frayed. Check CK and see if they have any kind of warranty.
 
Brad said:
I’m extremely surprised. The power lead in that hose must be super frayed. Check CK and see if they have any kind of warranty.
Click to expand...

Externally .... hoses looked brand new. They were the softer "superflex" braided style. That torch set is at least 10 years old. The new (used) stuff worked fine. Waiting to hear back with a number for the single replacement line.

Was surprised it was the hose as well --- but I'm not complaining, as it was the cheapest possible fix. I did pick up a new cable for a longer ground lead. Machine came with 25 foot torches and a 12 foot ground. :confused: That set me back more than I care to admit. But at least I won't have to move the machine around as much anymore.

For the time being --- it's over & done with. Been working on a WJ that is consuming more time than it should and I need to get back to working upstairs. :shaking:
 
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