This seems to be an issue with the Lower Y SUS/Buffer board in your set. It cannot be repaired on the component level - it must be replaced.
After you remove the back of the set - you will find two circuit boards on one side of the panel (usually on the left as viewed from the back) and only one circuit board on the other side.
The side with two boards will have one feeding the top half of the screen and the one board below it is the lower buffer board.
Just remove the board and replace it. there is no adjustments needed, but there may be shields and other boards needed to be removed to get to this board. Each model is different.
A service manual can help you tremendously:
CLICK HERE for one.
i am lloking at the tv sewt and there are 3 boards 1 main board with tuner 1 inverter driver board and one power supply board. the screen is connected via a board at the top please advise on what board i should be replacing?
Optional Information: Make: toshibaModel: 32AV502R
the above model is what i am asking about
Sorry for the misunderstanding - I did not realize this was a foreign set by the model number.
i see this is a 32" LCD without much documentation.
Most LCDs under 40" do not have a separate Y Buffer circuitry.
Instead this set uses a T-CON board which is your problem.
Try to replace t-con board that is located on top center of lcd panel and would be covered under metal shield.
This is the board you described as "the screen is connected via a board at the top" - that is the T-CON board.
Without the documentation (service manual) I cannot offer you a replacement part number. It should be silkscreened on the board.
If you need help with finding a replacement - please reply.