How to find transformers

[blodwyn]

I'm trying to switch some halogen ceiling spotlights for some LED bulbs, but I think I need to change the transformer for the lights in order to do so (I tried just putting the bulb in, but the light wouldn't come on, so I'm assuming it's an issue with the transformer). But I don't know how to find the transformer! Where should I look?

 

[andy007]

Pull gently on the wires through the light hole, it is normally very close to the hole

 

[endoftheworld]

These transformers are switch mode, so sometimes you need to leave a halogen bulb in one fitting in order to draw enough current for the transformer to stay on.

 

[SMR Bathrooms]

These transformers are switch mode, so sometimes you need to leave a halogen bulb in one fitting in order to draw enough current for the transformer to stay on.

Can you replace transformers with ones designed for LED fittings? If so will they still work if someone were to install a halogen bulb?