This is a short project that deals with adding simple potentiometer-driven foot pedal current control to a TIG welder which is missing the appropriate connector, but has the necessary connections on the front panel PCB in the housing.
The welder in question is sold as "Weldinger WE 200P ACDC" in Germany, otherwise it is known as the chinese "WSME 200". The same hardware was obviously rebranded multiple times and is sold in many different housing designs.
DISCLAIMER: First things first - I am not a professional electrician. Anybody who decides to modify his/her TIG welder the way I did (or in a similar manner) does so at his/her own risk. There surely is a risk of electrical shock and (possibly fatal) injury when working on a high powered welder, even when it's switched off and disconnected (because of the rather big capacitors inside), and maybe you can even burn your house down if you do something wrong. You will at least lose your warranty if you do this.
I bought a hobby grade TIG welder from a German DIY and Workshop supplier about half a year ago.
After watching a lot of Youtube videos / tutorials and reading reviews on different welders, I settled for a "semi-analog" machine with DC and AC functionality and most of the control options you see on far more expensive welders. I call it "semi-analog" since the options are controlled via 9 potentiometers and 4 switches on the front panel, so you can not store any settings or profiles (which does not matter for me as a hobbyist). The reviews on Amazon and some german DIY-Forums were also decent, especially concerning reliability and durability in a hobby environment. The german supplier even sells some spare parts. The device also comes with all relevant documentation in german.
The welder itself cost me about 450€ (End of 2018). It was about 10% cheaper than listed on Amazon when ordered directly from the supplier's webshop. As far as I recall, they claimed that the welder was their own design and was manufactured to their specifications in China.
The machine came with a TIG torch with "button start/stop" option and all necessary cabling + gas hose (except for the welding gas regulator). A foot pedal was not included, but the seller even today lists a pedal especially for this welder in his Webshop. I ordered one right away. The pedal was on back order from China, so I couldn't test it when the welder arrived.
After assembling the welder and doing some test welds in TIG mode, I found the start/stop button functionality a bit problematic, because (especially as a beginner) I never got the welding current / amperage preselection quite right on the first try. There is no way to fiddle with the controls on the front panel when you have to watch your welding area. So I had to stop my test weld, put the torch away, change settings and start over again very often.
The high frequency arc-start circuit also was not working reliably out of the box (which i know now, after fixing it - at that time I thought I was too stupid to use the welder).
It would sometimes work for 4-5 seconds and then go into "error mode" and not work again until the welder was power cycled. Also, you had to put the tungsten electrode very near to the welding material to get an arc to start (2-3mm) even under best conditions (totally clean material, reliable grounding, high starting current selected).
This resulted in multiple times of "dipping" the tungsten in the weld and having to regrind it. I blamed that mostly on my inexperience and thought the rather frequent electrode contamination was the reason for the "error" states of the welder.
When the foot pedal for the welder finally arrived, I noticed that it had two GX16 connectors, one with 2 and one with 3 pins. My welder only has one 2-pin GX16 on the front panel, this is also used by the button control on the TIG torch. After measuring the connections on the pedal side, I discovered that the 2-pin connector is only for start/stop and the output of the Amperage / Current control via potentiometer is on the separate 3-pin connector.
After checking again with the seller, they told me that the welder only supports start/stop functionality and that there...