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[unlucky mark mv6]

I know i have posted this before on here,but had no response really,so ill try again.Does anyone know how to test the various components inside a mig welder,as mine is down on power.Tried the obvious things first like earth connections,gun etc,all ok.

[Debs.]

Any sign of charring (and/or burnt-odour) on the rectifier diodes or from the transformer?

...aside from the above, or a poor/loose internal-connection and perhaps, a torch-power relay; there`s not much else that would leave you short of power, but still leave it working. :-/

[Kevin Wood]

Most likely one or more of the diodes in the rectifier have failed with those symptoms, IMHO.

Check first that there are no connections getting hot when you're welding - I.E. terminals for the torch or ground connection, transformer secondary, etc. as this would indicate a high resistance.

Kevin

[unlucky mark mv6]

No loose connections debs,as i have already checked everything like that,and no burn marks anywhere,but when i had it off my mate,i know it was full of bodyfiller dust inside,so i vacuumed it all out,and sprayed everything with switch cleaner.How do i test the diodes,is it just a case of putting a tester across the two legs,if so what kind of reading should i be getting,and can they be replaced?

[Kevin Wood]

No loose connections debs,as i have already checked everything like that,and no burn marks anywhere,but when i had it off my mate,i know it was full of bodyfiller dust inside,so i vacuumed it all out,and sprayed everything with switch cleaner.How do i test the diodes,is it just a case of putting a tester across the two legs,if so what kind of reading should i be getting,and can they be replaced?

Yep. With an ohm meter you should get a low reading one way round. Reverse the connections and you should get nothing in the other direction.

A picture of the innards might help identify the parts.

Kevin