How do I test the transformer of a Proficient s12 subwoofer?

[TadTV]

Hello, How do I test the transformer of a Proficient s12 subwoofer? Oddly only one leg of a 120v line seems to go into the transformer. The other seems to end right at the plug socket and it does not appear to be a ground. I thought everything needed both legs of a 120 volt circuit? Also, where is the fuse? It's not on the board or back? Would the fuse be in the middle of the transformer coil? Thanks

 

[KatieandDad]

It is not uncommon for transformers to have internal fuses, they are generally non-resetting thermal fuses.

 

[TadTV]

What about the input though? What am I missing with only one wire appearing to go into the transformer?