I worked at "The Only Sony Only" store in St. Louis when this TV came out. I delivered and installed equipment among other responsibilities. I might have delivered two of these particular units. I believe it was actually like 305 pounds.
This television had a couple of interesting traits. Sony flat Trinitrons were apparently the only true flat CRT televisions where both the outside AND inside of the tube were flat. This is why they were so heavy - the flat glass had to be thicker to withstand the vacuum inside.
It was a high definition television, but it was 4:3 aspect ratio. They sold a 34 inch CRT that was the only 16:9 CRT they offered at the time.
Additionally, the size of the 40 inch tube apparently left it extra vulnerable to stray magnetic fields. CRT screens all respond to magnets by producing rainbow colored distortions, but the 40 inch was extra sensitive. We delivered one to a house and turned it on only to find that the screen colors were distorted. I'm not sure how we figured it out, but we realized it was the proximity to the metal floor beam, so we moved the TV to another spot in the room and the color distortion went away.
For context, you could get an HD 65 inch rear projection wide screen television at the time that only weighed 265 pounds. I delivered both the 40 inch and the 65 inch up a flight of stairs. Those moving straps that hang from your forearms were not yet popular.