I apologize in advance for bumping this thread back from the grave, but I couldn't find my answer so a search brought this thread up.
I have the aforementioned problem with this TV, and these are the troubleshooting steps that I have done so far:
1. tested the fuse on the Y-sustain board with a multimeter (set it to the triangle with a line function and got a reading of 009, fuse is good)
2. unplugged top y buffer board(unplugged the 3 ribbon cables on the side), turned TV on and no video but audio
3. plugged in top, unplugged bottom y buffer board, turned on TV, same result.
I did notice that when the TV was on, a couple pixels in the top half of the screen would flicker various colors for a couple of seconds (only ~8 pixels did this) and then stop.
I have checked over all of the boards and have found no black spots or bad capacitors.
Can someone help me with the next steps? TIA