Horizontal lines across top of LCD TV

@ianwebster a failed T-Con board in general does not cause any horizontal lines. Horizontal lines are most commonly caused by failed Gate Drivers located along the side of the panel. These IC’s are mounted on a flexible cable(s) which are bonded to the LCD panel. Their function is to activate each row of pixels one at a time starting with the first line at the top. The gate drivers are activated by a single source of timing information so any single horizontal line or groups or random horizontal lines are caused by an output failure from a gate driver or a loss of the tab bond to the panel.

Put some pressure on the ribbon cables that enter the panel. See if that removes/worsens those lines. that would indicate a Tab Bond failure. Sometimes that can be repaired by adding some tape for additional pressure to the failed bond.