Murex tradesmig 165 lacking power

[Spark plug]

A friend of mine has just bought a tradesmig and brought it to me to test as he has no gas yet.

I’m told it had been stood for a long time as it came from a retired car restorer who had to stop due to ill health. The wire was rusty, so pulled that off then gave it a test and it is severely lacking power, you can just about weld with the voltage set to maximum but it’s defiantly not right.

this is what happens when set to minimum voltage, never seen anything like it:

I’ve checked the earth and tried another torch, anyone got any ideas?

 

[hotponyshoes]

Measure the voltage between the torch and return, see if it changes as you move the power selector switch
Check continuity of the torch power lead and return lead
Check the inside of the contact tip is not rusty

 

[Wozzaaah]

A faulty rectifier diode will cause lack of power.

 

[Spark plug]

All good stuff chaps, I’ve given in for the night, I will have another look tomorrow.

 

[andymfell]

manual with wiring diagram
http://murex-welding.co.uk/manuals/other/Instruction Manuals/Tradesmig 165-235-245-285.pdf