
Ah-ha!  I'm not alone at last!  Which Sony do you have??  I have a
27"SXR (pre-XBR series, circa 1987).  That damn thing used to
make noise like a mad-man.  I had/have 2 separate problems...one being the
flyback, the other was the assembly where the windings of the yoke
came together. 

First:  I found by poking around the windings on that assembly,
the thing would make noise.  I guess that there was enough of a potential
in that assembly to leak, so I sprayed it with a dielectric insulation
spray--I think it was urethane or acyrilic.  That fixed it.

Second:  Flyback...for the life of me, I can't isolate this one.  If I
leave the cover off, the TV will be quiet.  If I put the cover back on,
and let it heat up, it'll start to whine--kinda hard to solve with the
cover on!! :-(

A friend of mine who used to fix TV's says there might be a pin-hole
leak somewhere on the flyback.  Usually it's surrounded by a bunch of
black dust/dirt.

I hope this is a start...if you find something out, let me know!