Screen is black with a thin horizontal line

The t con board or LCD panel of the tv is faulty. Can confirm by replacing the t con board.
If you wish to get some details; check the site linked here. Pull up older posts.
http://electro-medical.blogspot.com/

If you wish to get some details; just Google for the site "Elelctro help". Pull up older posts. Surf the site with patience.
Line, faults & possible causes to LCD & Plasma screen are given with illustrations. You can get an idea about the fault to an extent.

Sustain board fault. Contact any service technician. This is not a user repairable fault.
If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/

Vertical scan section circuit fault. Check and replace damaged component/s at its vertical scan output section circuit. If you wish to get some details, check the site linked here. Pull up older posts. Check the site in 'Mosaic' view. It will make search easy. http://electronicshelponline.blogspot.com/

Unplug it,then wait 10 minutes,then plug it back in.

I'd suggest to bring it to repair shop if you're not technically literate

I fixed the problem by taking it to a repair shop

intermintence in vertical IC deflection its a job for experienced tech need to look for that circuit and do fine job resolding that IC

Is this a LCD TV? IF it is it could be something on the video processing board. Let me know the model # and well will go from there. Thank you Jay

this symptom, sometimes called the tube light effect, it is characterised by a bright thin horizontal line across the middle of the screen. this symptom is caused by a breakdown in the vertical deflection circuit. hence maybe the trouble maybe in the vertical oscillator, amplifier or output circuits. but if all i have said is not clear to you, better bring it to a qualified tv technician. good luck!