I have had the switch apart several times and put it back together,if anyone wants to know how just let me know,it works ok, the only thing now is that, when I pull the trigger to feed the wire without any wire,the motor runs to feed the wire but it seems to be taking to much current as the 13a fuse blows after a while,what can the problem be.
I numbered all the wires and took photos when I disconnected the switch,so the wiring should be correct, I tried the switch out using a 12v battery charger,I switched through the from 0 to 6 without the fuse blowing on the battery charger,this happened when it was wired wrong!
Its the original switch,with the links in the original positions.
I disconnected the 2 wires going from the transformer to the rectifier,and tried it,the welder runs OK until I pull the trigger,I do not have wire in it,so it cannot be to much resistance due to the the pressure on the wire.
I checked the transformer to earth and it's OK,I am getting continuity through the transformer.??
It could be the switch OR the transformer are causing the short (fuse to pop) You could try disconnecting the switch completely and bypassing it by taking one of the switch position wires and connecting direct to the live part of switch (brown in pic) The neutral (blue) should already be connected to the other side of transformer via pcb. TAKE CARE DOING THIS as there will be mains voltage present and voltage on any of the unconnected witch position wires. If fuse pops then try one of the other position wires, if still popping then fault is not with switch but must be in the main transformer OR on the pcb (small transformer on pcb maybe?)
Ref you last line in post 7, you should see continuity through the transformer so long as the windings are intact but would also show continuity if shorting between windings !
I think you could be right re the wiring,I bought this second hand and think that someone has wired it wrong, i have two lots of red white and black wires they are going to the live and neutral, they had live going to no 15 and neutral to 9/11.If I put the live and neutral to where it is marked L & N ,where does the red,white and black wires go?
Once I get this sorted I will try what you suggested in your last post.