Why do old tube TV’s power off into a bright dot

Question

Hey Reddit, help me figure out why old tube TV’s when they shut of have a shrinking dot in the centre that slowly fades out.

Thanks

In: Technology

Answer 1

Old tube TVs worked by shooting a beam of electrons, then using magnets to bend the beam so it lights up different parts of the stream.

If the magnets are off, the beam goes straight to the middle.

When you turn off the TV, the magnets get turned off, but there might be enough electricity left in the beam to fire off a few.
That’s the bright spot.