gas and live torch

[kenny 666]

my mig welder torch is letting gas out without pressing the trigger and it's live

iv taken the euro conection of and it's still gas flowing out so not the torch

could it be the SOLENOID valve but torch is live

or the contractor

thanks in advance

 

[kenny 666]

this is the welder

 

[Country Joe]

If it's staying live too, then possibly not the gas solenoid?
It's most likely a contactor (like a big relay) that's got stuck on, and needs a light tap (hopefully) to get it to free itself up again.

It would probably be easier with a photo of the inside of the welder, though - and then there'll be more specific replies, from the right folk.

People like @HughF & @eddie49 (plus quite a few others whose names I can't immediately dream up!) are likely to be able to identify the component with alarming ease & accuracy - you'll end up suspecting they may have been heavily involved in it's design!

Maybe stick a shot or two up, anyway.

Oh yeah - Welcome to the Forum, too!

All the Best,
CJ

 

[eddie49]

Normally the Contactor is switched on by a smaller relay on the printed circuit board ( PCB ), and that small relay is triggered by the torch. I think it is more likely that it's the small relay that has stuck on, rather than the large heavy-duty Contactor.
With the machine powered off and unplugged, open the casing and find the contactor. It is a black ( or white ) plastic block, about 3" square and 4" tall, with a lot of thick wires connected at rows of screw terminals. In the centre of the top there may be a square plastic button, which can be used to manually operate the moving armature and close the contacts. Push the button in, if it jumps out smartly when released then it's not stuck and the contactor is probably OK.
The small relay on the PCB may be in a clear plastic case. Gently pry the case off and check that the armature moves and the contacts open and close freely.
If none of these ideas help, or your machine doesn't have these components, then as CJ suggests, post some photos of the insides of the machine.

 

[Country Joe]

Sorry Eddie, (& Hugh, too!) - I have to admit, it kinda feels like I "fitted you up" there!

All the Best,
CJ

 

[kenny 666]

ok so have some photos of inside

whith the welder plugged in and on 0 nothing happens switch on to one and torch goes live without pressing the trigger and gas come out.

 

[kenny 666]

more

 

[kenny 666]

more

 

[Country Joe]

Hi there,

The first photo looks like the gas solenoid, and the second one seems to be the main contactor.
The relay itself won't be as big as that - and as said above, should be on the circuit board, somewhere.

You shouldn't have to get much "further in" from there - the circuit board is usually on display - it might even be somewhere out of shot, as it's fairly zoomed-in.
You can sometimes see inside the relay, throuh it's transparent casing, if it's not too filthy.

All the Best,
CJ

 

[kenny 666]

.

 

[kenny 666]

.

 

[Country Joe]

What's the clear blue rectangular box, on the circuit board on the left-hand side?
Sort of sandwiched below a round blue capacitor, and above a circular silver potentiometer.

That might well be it.
Looks quite likely - maybe a shot of the blue box, would help.

If it is the culprit, rip the top off, and do like eddie says above.
But carefully, they're a bit delicate.

All the Best,
CJ

 

[eddie49]

The Contactor is in post #8. With power off & unplugged, you might be able to feel and test the manual on/off plunger on the top.
If you release the white catch on the side, the contactor should slide off the DIN rail.
I think I see the relay on the PCB, behind the black component and above the circular metal cover of a potentiometer.
If you leave the side casing off, plug the machine in and switch it on whilst safely looking inside with a bright light, you may be able to see the relay move, and hear the contactor close with a "clunk".

 

[eddie49]

To get to the relay, you may have to unplug the multi-pin connector and pull off the other tags, then unscrew the PCB from the back of the front panel. Make a careful note of where everything goes.

The relay has an L-shaped operating lever - the armature. It snaps shut when voltage is applied to the relay coil. There may be a dual set of contacts operated by this lever. The moving contacts may open from one pair of contacts ( Normally Closed ) and then move to touch a second set ( Normally Open ).
This movement should be free, and all the contacts should be clean, not welded shut, and not burnt.

On some welders that small relay has to drive the main welding transformer, and so the contacts often burn or weld shut. On your machine, the small relay just has to run the operating coil of the large Contactor, ( and possibly the gas solenoid too ), so it has an easy life. Externally, your relay looks OK.

The welder has timers for Spot and/or Stitch welding. When those options are turned off, probably by turning potentiometer knobs fully anti-clockwise, there may be a switch that clicks off. If so, are these controls off, and do those switches operate smoothly?

 

[kenny 666]

yes both switches operate smoothly

The relay looks like it's moving and going between both contacts when I press the trigger

 

[eddie49]

The relay looks fine, contacts are like new, and you say it moves when you press and release the torch trigger. So it is doing its job, and yet the torch is live and the gas is on as soon as you power-on the main switch. That implies that the main contactor is always powered-on ( despite power for its coil being routed through the small relay ), or stuck on, or the contacts are welded shut.

When you power up the machine from the main switch, do you see, hear, or feel the main contactor closing already, without pressing the torch switch?

If you pull the white catch on the side, you should be able to slide the contactor off the DIN rail for a closer look ( with the machine powered off and unplugged ! )

 

[kenny 666]

no the torch is not live when machine is plugged in but goes live and gas flows when I put it the switch from 0 to 1 without pressing the torch trigger

 

[eddie49]

Sorry, I hadn't looked closely at the front panel photograph of your machine. Many welders have a main On/Off switch plus a switch or switches to select the welding power range. On your machine the 7-position rotary range switch has also got a "0" position which provides the "Off" setting.

With the welder case open you may see or hear the Contactor clunk into the closed condition when you turn from 0 to 1, or if you carefully put your hand on the plastic side of it you may feel the movement inside.
The Contactor is only supposed to move after the small relay has closed, and that only happens when you press the torch trigger. If you don't press the trigger, the small relay doesn't move, and so there should be no power going to the operating coil of the Contactor.

 

[kenny 666]

hi fitted a new contractor as had one ordered for it anyway. this didn't fix it so just going to wait untill places are open so I can get it looked at

thanks everyone for your help

 

[Sean]

Does it feed gas if powered on but torch disconnected?
The micro switch in the trigger isnt stuck?

Take the euro connector out and put a meter across the 2 pins in the torch plug, should be no continuity till the trigger is pulled.