Thank you for the video!Very helpful!
I've seen it and,I think that this problem can be caused by the Y sustain board,as well by the buffer boards.
Now,after you take the cover off,you will see on the left side(from the back),a big board in the middle left (this is the Y sustain) and this board connects to the 2 buffer boards(they are connected through some brownish ribbon cables to plasma panel).
Now,you need to take all the screws about from the upper buffer board and slowly pull it out of the Y sustain(totally out of circuit,with the exception of the brownish connectors from the panel).
Then turn the tv on with the board out of circuit.
If this was the bad one,you should see a good picture,but just on the lower half of the screen.
If picture still bad,reconnect all back ,put all screws back onto this upper board,and redo the same for the lower buffer board.
Turn the set on and check the picture.
If picture ok=lower buffer is at fault.
If picture still bad,then most likely Y sustain is bad-replace Y sustain.
This methods are pretty accurate,but the best way is to back up our decision is by measuring some voltages.
The most important ones are ,
VS,VA and VSC.Also VE will tell us about the integrity of X sustain board.VSC tells us about the Y sustain/buffers,and VS,VA should be ok-tells us if power boared operates fine.
On this model all of these voltages are measured and adjusted on SMPS(power supply board)-this is the board where the AC goes to.
The values for this voltages are written on a label onto the panel itself.
See attached pictures please:
Also sometimes the fuses on Y sus is open(Y sus is defective).
Here are the part numbers for Y sustain and buffers:
BN96-01211A Y sustain
BN96-00872A Y upper buffer
BN96-00873A Ylower buffer
I hope this helps,