Will Only Strike An ARC Once, Then Nothing... Also! Is Torch Permanently Live

[Cuma]

Bought a cheap DC Tig from usual suspect online recentlY.

I was just testing it out this morning and it has a weird problem in that when I switch the machine on it will strike an arc ONCE when i touch torch to grounded workpiece, then nothing else thereafter. I have to switch the machine off and then back on again to get it to strike another arc.
Yes its set to Tig mode and electrode negative...
Basicaly I was just testing for some life in the machine before I forked out on regulator and gas...
One other thing the trigger on the torch, is this just to activate flow on the gas as ive noticed that the torch seems to be permanently live, it will strike an arc even if i touch the workpiece without the trigger pressed on the gun... its just the gas solenoid that clicks when the gun trigger is pressed...
ANY HELP WOULD BE GREATLY APPRECIATED...
I am a first time Tig user so its all new to me, ive always wanted to try Tig, so maybe im doing something wrong I dont know..

 

[Tigman]

Has it got high frequency ? Or is it scratch or touch start ?

 

[Cuma]

Has it got high frequency ? Or is it scratch or touch start ?

i havent a clue, thats what im trying to find out now. its basic, basic, basic. has an on/off sitch and selector for 400v or 240v, its set for 240v. Also it has a current or amp dial, not sure which it indicates. it has a switch on the torch which ive checked with continuity on my meter and the switch is working fine. The torch is permanently live which ive read is normal and im guessing the trigger activates the gas. whatever i do i cant get it to do anything other than spark up when i touch the workpiece on first touch, then nothing thereafter. i have to turn machine off and back on to get it to spark again, but its not sparking then activating an arc like im guessing it should be doing...
I am going to test the gun to earth to see what DC volts are going on at the tip, ive not got an amp meter to test current though..

 

[500e]

https://www.cebora.it/articoli_fuori_produzione_uk.html
Lots of manuals

 

[Tigman]

If it's scratch or touch start place tungsten onto metal being welded press trigger and lift up torch so you the have a 2mm gap between tungsten and metal then arc should continue ,if you pull awAy too far arc extinguishes

 

[Tigman]

Yeah sorry scratch it and pull away or touch down and pull away !

 

[Richard.]

The central toggle switch right at the top wants to pointed right.
This is your (lift/Hf) control.
Flick it right. Grind up a sharp tungsten
Make sure you’ve got argon gas on. Hold the tig torch so that the tip of the tungsten is 2mm away from the job. Press and hold the trigger.
If you short cut or miss out any of the advice above you will effect its ability to strike and hold an arc.

 

[Richard.]

The permanent live thing is only normal if it’s live/scratch tig. Which if that’s the case when the toggle switch is pointed left that makes sense. It will make the torch live.
The toggle switch pointed right like I suggested for Hf should do more than just activate the gas. It should activate a small high voltage spark and it should make the torch live. In this mode the torch should be dead without the trigger pressed.
My only concern is you say you have to reset the machine after an attempt start. That doesn’t sound normal. Try it in Hf and see if you get any more issues. I assume your supplying it what it needs and being set to 240v it’s all present and correct. (No jumpers or wiring to change etc).

 

[Cuma]

I think i may have more serious problems..
opened up the machine and there is a 24vac relay on a small pcb board at back of machine, im guessing that this relay is linked to two things as the main heavy duty wires from the transformers are linked to this board and one other thing is two wires out the top of this relay pcb that goto the main pcb at front of machine that mostly everything else seems to goto and be controlled from.. ALSO this relay isnt moving of its own free will no matter what i do. BUT!!! ~When i close the relay with a plastic pen and hold it closed, when i hold the torch onto work it get tiny little sparks and when i draw away im able to get a tiny little blue arc going, but its tiny and more than 2mm away from work and i loose it. Also if I turn up the current dial on front of the machine it does sod all to give this little arc any more or any less oooomph!!!!
Also it doesnt have an HF toggle switch.. the only switches this machine has are a toggle switch for selecting Arc torch or Tig torch modes, which im obviously in tig mode..
heres some pics of the inside if it can help you point me to where my problems may be..
Like i say all ive found so far is that if i manually press in the relay thats not triggering alone i can draw an arc, but its weak and isnt affected by changes in the current dial on front of machine...

 

[MattH]

You need to be testing with gas.

 

[Cuma]

The central toggle switch right at the top wants to pointed right.
This is your (lift/Hf) control.
Flick it right. Grind up a sharp tungsten
Make sure you’ve got argon gas on. Hold the tig torch so that the tip of the tungsten is 2mm away from the job. Press and hold the trigger.
If you short cut or miss out any of the advice above you will effect its ability to strike and hold an arc.

The only toggle on the machine is up and down and it indicates for arc electrode or tig torch, so obviously its switched to tig torch... the only other dial is for current and an on off switch and thats it... no other switches buddy

 

[Richard.]

The only toggle on the machine is up and down and it indicates for arc electrode or tig torch, so obviously its switched to tig torch... the only other dial is for current and an on off switch and thats it... no other switches buddy

So it doesn’t look like this then?
Your pic is difficult to make out but I think this one has 2 switches.

 

[Cuma]

So it doesn’t look like this then?
Your pic is difficult to make out but I think this one has 2 switches.

Ive finaly taken all four PCBs out of the welder and im going to go thru them and see if any components are bad and go over a few solder joints incase...y manulaand if i push in this rela
The fourth pic numbered _016 is the 24vac relay that i have to remove the plastic clear case and if i weak arc close the contact with a plastic pen by pushing on it to keep it closed i can actually get the machine to kind of make a weak, weak arc. but its tiny and very weak, the current pot does nothing if i increase or decrease th1.is. also this board has 3 pairs of spade connectors and each pair of wires comes from and goes to 1. the main pcb front panel board. 2. down to what look like rectifiers or diodes? not sure, long black blocks that are connected in series with metal strips and they have what looks like some for of bleed device bridging between each connector, but they look like disc capacitors rather than a bleed power resistor that youd find in this kind of arrangement on capacitor banks to bleed them off at powerdown. 3. down to main transformer..

 

[Cuma]

there is also this strange green wire, the only solid green wire in the machine, it isnt a ground and their are yellow/green ground wires used for grounds already in the machine..
strangely this green wire comes from what looks like some kind of bridge rectifier arrangement in the bottom of the machine, then the wire goes from this rec arrangement upto the small pcb board with the 24vac relay on that ive mentioned already... I cant understand why this green wire is cut and not connected to anything. see pic

 

[Cuma]

You need to be testing with gas.

surely i should still be able to see if the machine is generating an arc even without gas, i just wanted toi test it working and producing arc before i spent on regulator/flow meter and gas..
holding down the 24vac relay that isnt activating alone is alllowing me to generate an arc of sorts, when i touch the work i get tiny tiny sparks, like fizzy teeny things then pulling away opens up a bright blue arc, but it looks weak and its tiny, very very small and weedy, i loss it easy too, just over 1mm lift and it goes.

 

[Cuma]

So it doesn’t look like this then?
Your pic is difficult to make out but I think this one has 2 switches.

yes its the same as this but if you look at the toggle its up and down not left and right and i dont think thats indicating some kind of lift start, its signaling either arc electrode mode or tig mode... mine is set for tig mode. plus the big right knob is just an on off switch and its right for 400v on, or left for 240v on... then the only other knob is for current selection thats the one below the toggle switch. then everything that should be present on the far left where this one has empty holes, mine is blank, doesnt even have holes. some have extra knobs and a socket there where you can plug in a footpedal and a remote for finer tuning parameters, mine is just basic basic basic tho..

 

[Cuma]

The permanent live thing is only normal if it’s live/scratch tig. Which if that’s the case when the toggle switch is pointed left that makes sense. It will make the torch live.
The toggle switch pointed right like I suggested for Hf should do more than just activate the gas. It should activate a small high voltage spark and it should make the torch live. In this mode the torch should be dead without the trigger pressed.
My only concern is you say you have to reset the machine after an attempt start. That doesn’t sound normal. Try it in Hf and see if you get any more issues. I assume your supplying it what it needs and being set to 240v it’s all present and correct. (No jumpers or wiring to change etc).

No from what i see its hard wired from factory for either 240v or 415v. i think its just a generic fron sticker, one size for all kinda deal. it isnt switcheable between 240v and 415v.

 

[Richard.]

surely i should still be able to see if the machine is generating an arc even without gas,

Ok well good luck finding the problem I don’t know much more.
Yes I would defo test with gas it makes fault finding all the more easier and gives you much better idea of if it’s doing what it should. For one you say the arc won’t stay on. Having no gas will make this worse.