My sony XBR is quite old (92 vintage) but still love the great picture.
Recently it developed the problem of horizontal bands of light and dark
across the entire screen which only appear in light scenes. If the picture
is dark, there are no bands and the intensity or how visible the bands are
is in direct proportion to how bright the picture is. It appears that the
bands are a distortion in the vertical sync. Thought it could be a power
supply related problem because of the sensitivity to brightness level. I do
have the service manual for the TV. Any suggestions on where to start
looking would be greatly appreciated.

Thanks in advance,
Dan