Thanks Eddie , I will give it a go tomorrow , thanks for the linkI cannot find a wiring diagram. I'm pretty sure the machine was made in PRC. Not much chance of a replacement part, unless you can find another one in "spares & repairs" status.
Have you tried disconnecting one wire to the rectifier, checking if the tranny still overheats, and measuring what the secondary voltage ( if any ) is ?
It is unusual that a mains transformer would short-circuit. Well, a proper one shouldn't. If you can find out how the primary tappings are arranged ( e.g. a 1-pole 6-way switch ), you could try just wiring one of the primary wires plus any one tapping to AC mains in case the fault is in the selector switch ( e.g. it is feeding 2 circuits simultaneously ).
If you have a sensitive low-range Ohmmeter, you could try a resistance check on the primary. See post #7 of this thread:
Sealey 180 supermig v3
My uncle has asked me to look at his Sealey 180 V3 but it looks like someone has been in there playing as some of the wiring looks (from the supplied schematic from sealey) to have been messed around with. One quick question, there is a sort of ferrite ring bolted through the base with red and...www.mig-welding.co.uk
Thanks Andy for taking the time to help a numpty lol , I do appreciate the help honest , this is where my head is saying don’t touch live and neutral together or pop lol but the resistance in the wire is what’s stopping that from what I’ve gathered ? ,The primary side sequence should be like this:
The thinner single wires (call them 1 and 7) at each extreme represent the ends of the primary and thus give the lowest welding voltage when AC is fed to each. (and the highest resistance reading).
The five taps in between them are 'loops' out for the other five voltage settings.
You can see their relative positions, e.g. second left (2) gives the highest welding voltage setting when AC is fed here (i.e. 1 and 2) so this has the lowest resistance.
If you can't see their actual order (3,4,5,6), as the primary coil enlarges outwards, then the resistance measurements should confirm their position, if your meter is sensitive enough.
The loops may look like two wires, because the (rotary switch) screw terminal connections often break the loops in use, so for resistance testing one has to ensure that broken loops have continuity.
Hope that helps, Shaun.
Brill - will give it a blast tomorrow , ThankyouYep, that's right. Just think of the primary winding as one long piece of wire with five taps looped out for voltages 2 to 6.
L and N don't matter for this testing, as it's AC voltage.
Be safe, though....
Some MIGs have the two laminated cores - the main transformer and the choke - welded together, one on top of the other. However, they work as separate components, the windings and the magnetic fields in the cores are self-contained. Perhaps the "stacking" is just to save mounting brackets and bolts. If yours are like this, and you cut the welds, then the old 170 Amp choke can certainly be used with the new transformer.I haven’t got a choke - can I use the choke of the old transformer - new one is 165 amps old one was 170amps