PHILIPS 28PW9616C CHASSI SMG7.1E AA? HALF SCREEN BLACK?

[msandig]

As a Christmas present my TV developed a weird fault.

The screen has collapsed to the horizontal envelope in the middle: the top half is black, then 1/3 has a perfect picture(not squeezed, just cut out), and then the rest black again. Both top and bottom borders of the envelope have bright lines. It looks like all signal is concentrated in those border lines and is not unwound properly. The picture collapsed as we were watching and never came back. Tried to switch on/off, whatever- the same.

Your helpful thoughts are really appreciated! Hope that could be a simple fix....

Many thanks...