There is nothing wrong with this transformer.
As I said in post #5, often the fuse fails when the transformer isn't faulty - either the fuse just fails (not unknown), or the transformer has overheated because of excessive loading on it. The third option (of course) is that the transformer is faulty, and has shorted turns causing it to overheat.
I had a
MAJOR row with Sony (went on for two-three years
) - about repeated failure of the mains transformer in a rather nice Sony amplifier. The amplifier was rated at 100W+100W RMS continuous, and looked a really nice amp, the customer (who was young, and presumably played it LOUD!!) brought it back dead, and the mains transformer was O/C (or at least the internal heat fuse was). I was surprised at how light the amplifier was, and once the top was off, at how small the mains transformer was - and also at how much space there was around the transformer - as if it had the wrong transformer fitted?.
I replace the transformer under warranty, and it failed again later when the unit was out of warranty - which resulted in my row with Sony.
Comparing the transformer size and weight to others, it was only rated about 75-100W,
FAR too small for a 200W amplifier, and eventually Sony agreed to supply a new transformer for free - but only the exact same 'too small' one.
As I see it the unit was designed for a suitably sized toroidal transformer, the space for it was there, and the small one even had to have a special mounting bracket to make it fit in the larger space - presumably some 'bean counter' had altered the specification in production and fitted a much cheaper transformer, assuming that no one would ever play it loud.
Anyway, Sony would never admit to the manufacturing error, and just insisted that failure rates had been low.