Hello , my name is Jack Perhaps I can help you with this problem but first i would have a few questions;
If you knock or tap on the TV's frame (left or right ) beside that line , does it seem to affect it ?
Does it seem to get better/worse as the tv warms up or stays the same ?
stays the same
O.k then at this point it would look like you may have a defective scan board .
In most TV's there are 2 of them (upper/lower) but right now it looks like yours has one long board instead of two.
I`m having some difficulty this morning to locate this board in the UK and one of the main supplier`s website does not respond .
Did you wish to look into repairing this yourself perhaps or just have an idea of what is involved and the cost of repairs ?
just a idea of the cost of repairs
O.k then as I was saying this would be caused either by a defective Y-scan drive board or perhaps a bad connection on one of its connectors.
This board if it has to be replaced ,cost around 20 to 30 pounds and you can expect another 60 to 80 pounds to have this done at home .
So all in all perhaps 90 to 110/120 pounds .
Bit difficult for me to say what the repair shops in the UK charge for a service call these days.
If you`d like to find a Samsung ASC (authorized service center) near you , click on the link below and enter your postcode and the info about your tv ;
This will list the closest ones to you.
Wish i had better news and an easier solution for you today but i hope this help and I will be in standby if you have any questions.Thank you and please take the time to rate my answer if that answers your question and you can still reach me here at anytime after this chat is closed if you have other questions.
Please note that from where i`m sitting there is just so much that i can do and if you are going to rate my answer below O.K service then please do not rate at all , just let me know.