Hf Arc start board

[Seadog]

I've sketch out a rough (very rough) circuit for this, and from what I can see it will not generate a spark on its own. It needs a drive into the 2-pin connector adjacent to the 24v input. I would say it's looking for a square wave or similar.

 

[migmug]

The new HF PCB you have seems to be a clone of one for the Riland LGK80/100 plasma cutter.
I could not find a diagram for the the LGK range that matched the PCB.
Based on fixing a few plasmas, looks like
1. The output 1/4" connectors go to a HF coupling choke in the negative line
2. The connector between the transformer and large relay is the control 24V DC
3. The connector near the small film capacitors is power in, they take it from a 3rd coil loose wound on the main power transformer.
4. The connector between the large film capacitors and large relay is most likely for the pilot arc, that would connect to a current limit resistor in the + line.

The old hf generator looks one I once saw in a Fimer machine might be a TIG star something, I will look around to see what I can find

 

[Nickedemuz]

Thanks to all of you. I will continue this endeavor tomorrow

 

[migmug]

Found it Fimer Star Tig 160, there was a picture on here Hf gen top right, not seen my diagram for about 15 years.

The original looks very odd, no low frequency transformers, must use rectifed mains directly for a power source.
Found you can get things they call "Inverter argon arc welder high frequency arc ignition DC" they look like only need dc to generate the spark but I expect you would need a coupling inductor and a hf return capacitor, images below are only examples, again research well first. You might need extra filters or screening to protect the rest of the welder.

 

[Nickedemuz]

Found it Fimer Star Tig 160, there was a picture on here Hf gen top right, not seen my diagram for about 15 years.
View attachment 274707

The original looks very odd, no low frequency transformers, must use rectifed mains directly for a power source.
Found you can get things they call "Inverter argon arc welder high frequency arc ignition DC" they look like only need dc to generate the spark but I expect you would need a coupling inductor and a hf return capacitor, images below are only examples, again research well first. You might need extra filters or screening to protect the rest of the welder.

View attachment 274715

View attachment 274716

You have a good memory
That does indeed sound like mine. It also looks a bit similar. This is how mine looked before I (literally) cooked it:

I just realized I also must have misinterpreted the schematic. I though the 60-70VAC applied when pressing the button only flipped a relay, but since it passes an hf filter it might be the driving voltage?

 

[Nickedemuz]

Found it Fimer Star Tig 160, there was a picture on here Hf gen top right, not seen my diagram for about 15 years.
View attachment 274707

The original looks very odd, no low frequency transformers, must use rectifed mains directly for a power source.
Found you can get things they call "Inverter argon arc welder high frequency arc ignition DC" they look like only need dc to generate the spark but I expect you would need a coupling inductor and a hf return capacitor, images below are only examples, again research well first. You might need extra filters or screening to protect the rest of the welder.

View attachment 274715

View attachment 274716

I should already have understood this by now but admittedly I don’t. Why do I need the coupling coil? The old hf generator didn’t have one but most of the diy projects I have seen have a coupling coil. I surely am missing something obvious here but I am relating to the original hf genny

 

[migmug]

At work during the day so can only post at the weekend or after 6pm uk time.

Old hf generated did not need the coupling coil because it was designed that way.

The parts you can get from china are all based on spark gaps and all system I have seen with those couple the HF via a coupling coil, and so the need to look for a similar system to get ideas what you need, you see the reason for research.

Back to the old system I think the voltage to 10 and 12 on the hf generator is used to contol the hf, it will be around 60v with not arc so there is need for hf, once the arc starts this voltage will drop to welding voltage level and the hf will stop.
I would do measurements in the area to confirm 100% the voltage in AC and DC when welding and when not welding but trigger pressed.

 

[Nickedemuz]

I really appreciate your answers I find this very interesting and it is fun learning about it.
Like many others I bury down into YouTube looking for good videos about it. Not very much in detail about how arc starters work though. Most videos are about showing the arcs but not so many about the details.
Will continue my journey towards tig arc start epiphany