When Good Transformers Go Bad...A Lesson

[W3GMS]

Hi Chris,

Many times not enough primary current flows to blow the fuse.  It depends on the failure mode within the transformer.  I think it is good practice to use some secondary fusing in case a filter cap or something else downstream starts to pull excess current to slowly overload the transformer but not to the point where it pops the primary fuse.
 
It sounds like your DX-100 XMFR was a slow burn! 

This stuff is pretty old and its bound to happen.  Our best friend may be the transformer re-winder!

Regards,
Joe, W3GMS