problem with snap on 130

[moggy]

ok was welding yesterday for approx 3 hours ,all fine no problems.
went to do a bit just now and was welding funny like the gas wasnt turned on (but it was you could hear it) then all this smoke appeared from nowhere.
turned the power off and the mains lead is fried! the yellow and green earth lead has burnt through the lead,
anyone know what would cause this?
can fit a new lead but dont want it to happen again.
socket didnt trip , or the fuse in the plug.

 

[malcolm]

That's dangerous looking. Do you not have an RCD fitted somewhere in your supply?

My guess is the output to the torch has shorted to the case on the welder (check for the fault), and that's gone down the earth wire. An RCD would catch that instantly and shut off the supply. A burned earth wire is frightening - if you had touched the machine you could be frazzled too.

Before you try to fix the welder, could you post some details of the electrical supply you have - it's not an old fuse wire type is it?

 

[rtbcomp]

An RCD probably wouldn't catch that fault as the mains current in the live & neutral would still be the same.

Certainly looks like welding return has found its way to the case though, with the workpiece connected to earth too.

 

[moggy]

these 2 rcd's come off the main fuse box, i was using the bottom one, and normally they are so sensitive that if you turn the machine off they sometimes kick out on the rcd.

very funny that it has suddenly gone like that, scared the crap outta me lol.
gotta find out where the problem is.
ill take the torch apart, gotta start somewhere.

 

[malcolm]

True enough rtbcomp - the earth doesn't go through the RCD does it.

Forget what I said, apart from the bit about the output current to the torch grounding to the welder case somehow. SIPs are bad for that where the torch passes through the front of the case. I'm not familiar with the Cebora.

 

[moggy]

ok what am i meant to be looking for, there are no burnt wires, the feed wire that goes to the torch passes through the plastic moulding , not damaged in any way
all looks ok at the torch end.
the mains lead comes in the back of the case goes through the plastic allen key screw down holder, then live and neutral go to the on/off switch and earth to the case.

 

[Robotstar5]

If you have a meter, check for continuity between melted earth and torch tip - should be open circuit

 

[rtbcomp]

It's the welding earth to machine case/plug earth you should be investigating.

You weren't standing the welder on the workpiece were you?

 

[moggy]

ok im not great with electrics so bear with me , have a meter and done a continuity test between burnt earth and case, Fine
and torch earth and connector on chipboard. fine
other than that it doesnt matter what switches i play with i cant get a connection after the chipboard connector.
chuck it in the bin and buy a new one ?

 

[moggy]

no the welder was on concrete and i was welding my trailer that was about 3 foot away.

 

[rtbcomp]

Have you checked that there is open circuit between case & welding earth?

 

[moggy]

just checked and there is NOT an open circuit between case and welding earth.
there is a open cicuit on the welding earth cable to circuit board.
makes me think its that.

 

[rtbcomp]

That's your problem, welding earth has shorted to the case, suspect where the welding earth comes out of the case.

 

[moggy]

had it all apart, literally no damage, it might have shorted to the case but i cant find it.
it comes out the end of the torch then through the plastic wire feed.

 

[the snooper]

is the earth wire like that throughout the entire cable or just at that end ?

 

[moggy]

complete cable all the way to plug.
thanks for all the help by the way.
Mark.

 

[the snooper]

is the welding earth shorted to case senario going to be correct 100% as ive known people weld their mig case with the welder they are welding.
it has also been reported on the forum that people have done it will no problems.

think im going to earth something connect it to my earth clamp and weld just to see if i get the same results

 

[moggy]

think ive sussed it, my shed is metal, if the shed door was touching the trailer would that cause it to melt the earth? and if so will it be ok or have i just ruined the damn thing.

 

[the snooper]

is there any chance that you had the earth clamp sat on top of the welder at any point and tried to weld not realising you had left off the clamp

 

[moggy]

no i always connect it all up before i turn it on at the welder