Step-Up Transformer trouble. 110v into 220v

[cybertronicify]

Hey everyone. I have a step up transformer i recently bought, but to my surprise the Neutral of the Input plug is a dead SHORT to the LINE of the 220v output. And the LINE of the input of also 6 OHMS to the Neutral of the 220v output. The transformer is working fine and i have taken it apart to check for circuitry, there is none. I always thought that the step up is isolated but it looks like now it is not isolated at all, can someone please explain to me how that works? I have attached a screenshot of a crude diagram i drew with Eagle.

[Simon]

can you post a picture. They may have not wanted to have the output floating, you can connect the two "neutrals" together, it may even be that you have some sort of autotransformer.

[Andy Watson]

It will be an autotransformer. Basically, it takes one 110V winding and stacks it on top of another 110V winding. This saves materials (and money) by utilising one of the 110V windings twice. It only needs three terminals - I guess it is manufactured with four terminals for convenience of wiring. It's slightly surprising that the neutral in is labelled as the line out, but as you say, it works.

Alternatively, think of it as one 220V winding with a 110V tap.

[cybertronicify]

Ahh ok, its getting late here ill post of pictures tomorrow.