It's a very common TV fault symptom (field/frame collapse).
Often due to leaky electrolytic capacitors or dry joints in the frame output circuit. Usually cheap to fix and worth repairing.
Don't run the TV while it displays a bright horizontal line as it can burn the screen phosphor and leave a permanent image.
Cobweb
July 2006
howtomendit.com for free repair help, information and advice.
