Cebora TIG Uno not working on AC (old 3 phase machine)

[Hebweld]

3 phase Cebora Special Tig Uno 200amp (pics below) [edit: should have said 2 phase + neutral]. It's the one with the wind-up handle on the transformer i.e. old school with minimal settings. It's been working fine for approx 20 years but it's suddenly developed a problem in AC mode. It'll strike an arc between the tungsten and workpiece but it's super weak and there's no way it'll even think about melting the aluminium. Everything's working OK in DC mode. I've had a search around the forum and saw mention of cleaning and adjusting the points. They were sparking but I cleaned both pairs and reset them anyway. Still can't weld in AC.

I've seen mention of the capacitor being a possible cause. I've not swapped it for a new one yet. Does the capacitor affect the AC side of things only? I got the local electrician to check capacitance (my cheap meter doesn't have that function). He said it was OK when powered up but empty when the welder is switched off. That's all the info I have at this stage.

Thanks in advance for any advice etc.

 

[Hebweld]

Problem solved! Just found another thread on here mentioning a points gap of 0.008"
Mine were too wide. Just reset to .008" and it's welding aluminium again!
Should have done more searching and less posting

 

[cumbriasteve]

Welcome to the forum and glad you found the solution

 

[Hebweld]

Back again, with the same problem... not working on AC but fine on DC. I first had this problem back in January, but got it working after I cleaned and reset the points (as mentioned above). A couple of months later, same problem, followed by the same fix i.e. it was working OK again on AC. I fired up the welder this afternoon. Same thing's happened again. So I've cleaned and reset the points (they looked OK), but no joy. I cleaned the points by running the tips flat against a linisher, then set the gap on both pairs to .008". I've replaced the capacitor as a precaution, but that hasn't helped. I'm stumped!

 

[Pete.]

I think you should go back to the points and go again. I might hazard that using the linisher was a poor idea, those faces need to be very flat and very parallel. The manual actually advises you not to clean them. All I did was rub a feeler gauge through the gap.

https://www.cebora.it/manuali/fuori_produzione/890/ist_900_eng.pdf

 

[Hebweld]

I think you should go back to the points and go again. I might hazard that using the linisher was a poor idea, those faces need to be very flat and very parallel. The manual actually advises you not to clean them. All I did was rub a feeler gauge through the gap.

https://www.cebora.it/manuali/fuori_produzione/890/ist_900_eng.pdf

Thanks Pete. Wondered if the linisher might have been a bit OTT

Any idea if points for these old machines are still available? Not managed to find anything online so far.

Thanks for the manual too - not seen that before

 

[WorkshopChris]

Wondered if the linisher might have been a bit OTT

Not sure about this make but hv points are often brazed tipped with a thin disk of precious metal often platinum, you may of removed this causing the steel underneath to ware away faster with the arc action.

 

[Hebweld]

Not sure about this make but hv points are often brazed tipped with a thin disk of precious metal often platinum, you may of removed this causing the steel underneath to ware away faster with the arc action.

Yep - I reckon that's exactly what I've done

 

[Pete.]

Inspect the end of them closely to see if the tungsten tip is still there. If it is I would make up a basic jig to hold them dead square against a lapping plate and lap them flat again.

 

[slickrickladidadi]

3 phase Cebora Special Tig Uno 200amp (pics below) [edit: should have said 2 phase + neutral]. It's the one with the wind-up handle on the transformer i.e. old school with minimal settings. It's been working fine for approx 20 years but it's suddenly developed a problem in AC mode. It'll strike an arc between the tungsten and workpiece but it's super weak and there's no way it'll even think about melting the aluminium. Everything's working OK in DC mode. I've had a search around the forum and saw mention of cleaning and adjusting the points. They were sparking but I cleaned both pairs and reset them anyway. Still can't weld in AC.

I've seen mention of the capacitor being a possible cause. I've not swapped it for a new one yet. Does the capacitor affect the AC side of things only? I got the local electrician to check capacitance (my cheap meter doesn't have that function). He said it was OK when powered up but empty when the welder is switched off. That's all the info I have at this stage.

Thanks in advance for any advice etc.

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Hi!
I have just been given this same model but I'm struggling to find a torch with trigger or pedal
would you know of where I could get spare components for this machine/ I see this post is from a few years ago, would you be willing to sell me some spare parts?
all the best