DIY Foot Pedal for Thermal Arc 202

[cranker25]

Hi,

New welder, old electrical tinkerer here.
I recently picked up a second hand Thermal Arc 202 to learn the ropes of TIG on, after being really quite happy with my Parkside flux core introduction to MIG.

I was surprised to see quite how expensive the compatible foot pedals are, so decided to post some details on building your own.

The first thing to tackle was the connector, as although some companies were selling spare plug for about £25, I could not find any information about the actual make/model of the plug.
The instruction manual details the pinout, but not the part number.
After some searching and test fitting, I believe it is a TE Connectivity AMP CPC (Circular Plastic Connectors) Series 2, 8 pin, reverse gender.
Male plug : 206434-1
Housing Backshell: 1-206062-7
Male crimps: 66506-9
You will find all of these part numbers availiable as free samples from TE, if you are a "business" ;-)
I got away with using a crimp tool for Molex XH pins, sure you could use some pliers in a pinch.

The next piece of the puzzle was a pedal. I found a pretty generic one with a 1k pot from Aliexpress for about £30. It was sold as a HZXVOGEN 5 Pin Foot Pedal For HVT250P.
The manual seems to explicitly call out a 5k pot. If it is just used as a voltage divider, I don't see it making much difference. If the signal is current driven to eliminate noise, maybe this will come back to bite me.

I hooked the terminals up as follows (your cable colours may differ!)
2 - Red (switch)
3 - Black (switch)
5 - Blue (Pot hi)
6 - Yellow (Pot lo)
7 - Green (Pot wiper)

The second pot on the back limits the maximum.

I will report back once tested!


- Chris

 

[hotponyshoes]

You can get the pins in a solder version.

It's also worth getting the terminal removal tool so they can be re-used if you put them in the wrong place!

 

[fizzy]

I agree - way over priced for what they are!

 

[tom2207]

I agree - way over priced for what they are!

try a fronius one ,,,, they have a sneaky board in them to stop you swapping them about ,,,, some days your the dog and some days your the lamp post ... but I wouldnt be without the option of using one , some days you dont need a pedal at all and other days you wouldnt be without one ,,, a simple on off non latch pedal can be a mighty handy tool too and they can be rigged up cheap

 

[tom2207]

and of course ,,, welcome to the forum.

 

[cranker25]

So the aliexpress pedal had a 1k pot on the back to set the maximum current, and a 10k slider pot on the pedal. The wiper from the 1k pot fed the top end of the 10k slider.
The resistance was obviously a bit lower than the machnie was designed for, and I could only get up to about half current.

I replaced the max current pot with a 10k rotary pot, and it works like a treat!
Seeing as you can set the max current on the front panel of the machine anyway, I suppose you could just bypass the max current pot to achieve the same thing.

I also added a rocker switch in series with the trigger switch so you can disable the trigger and preview the max current with the pedal down for adjustment.