For all microwaves the transformer will be situated to the side of the cooking chamber and behind the operator control panel.
Clearly your microwave is broken and a kind friend has suggested that the transformer (whatever that is) might be defective - you imagine yourself making the repair.
Don't even think about it - you will not have the special tool to remove the outer cover and inside you will find dangerous radiation and very high voltages - even when switched off and unplugged.
It's a safety thing - users are actively discouraged from poking around inside them.
https://www.youtube.com/watch?v=WeIqj_Ne1_g
Good luck...
April 2015