Need some infos about this particular transformer please !!

I have a welding machine that contains a little transformer going directly to a relay that allows the voltage to pass through the SMPS to the main board then to the DC transformers directly to the + and - outputs of the welder .
Now as soon as i turn the machine on i don't hear any relay clicking , that's why i want to check it , i am just wandering what is the safest input voltage i should put in ?? and should it be DC or AC , just to avoid any damage on the transformer ( if its still good ).
Here is the transformer :
**broken link removed**

And the thing that i don't quite understand is how could that relay be energized if there is already no voltage attenuation to the card containing the transformer

ALL transformers only work on AC - and in this case it's a switch-mode transformer.

However, it's VERY rare for such transformers to fail, it's far more common for the SMPSU itself to fail.

Nigel Goodwin said:

ALL transformers only work on AC - and in this case it's a switch-mode transformer.

However, it's VERY rare for such transformers to fail, it's far more common for the SMPSU itself to fail.

Click to expand...

Thanks Nigel for this , here is little description of the situation .

The unit i got is a 200A welder : it has a SMPS card containing inputs for mains and 6 470 uF electrolytic caps and two power rectifiers , this card has two connections , 1 for rectified mains going to the PWM motherboard that has also an output for another card containing 3 transformers (EER43x15 21:4) that are finally delivering current to the outputs of the welder .
The second connection is for the(24 v dc ) relay , but this one is an input that comes from the PWM motherboard it self .

Any ideas on what could be stopping the relay from being energized ??

You really need a circuit to see how it's supposed to work - you don't repair stuff by randomly checking components.