The short answer
Change the input and the source. If the lines stay identical on every input, including the TV’s own menu, the panel or its internal ribbon connections are at fault. If the lines change or disappear on another input, it is the cable or the source device — and that is cheap.
The TV’s own settings menu is the key diagnostic, because it is generated internally and does not travel through any input. Lines visible on the menu screen prove the fault is inside the television.
Reading the pattern
- A single thin vertical line, one colour — usually a stuck column in the panel or a failed driver connection. Internal.
- Several vertical bands — commonly a failing T-Con board or ribbon cable. Internal, sometimes repairable.
- Horizontal lines that flicker or roll — frequently the source or the cable, especially if they change with content.
- Lines only in certain colours or scenes — a signal or bandwidth problem. Check the cable.
- Lines that appear when the TV warms up — a failing solder joint or connection expanding with heat. Internal.
- A spreading crack pattern or a dark blotch — physical panel damage, not repairable economically.
The tests, in order
Open the TV's settings menu
If the lines appear over the menu, the fault is internal and no cable change will help. This is the single most decisive test and it takes ten seconds.
Change to an unused input with nothing connected
A blue or black no-signal screen showing the same lines confirms the same conclusion.
Swap the HDMI cable and the port
If the lines only appear with one source, change its cable and move it to another port. Failing cables produce sparkles, bands and intermittent lines, particularly at 4K.
Power cycle the television
Unplug at the wall for 60 seconds. Occasionally a display driver hangs and produces artefacts that clear on a genuine cold start.
Apply gentle pressure at the edge of the bezel
If lines change or vanish when you press near the frame, a ribbon connection has worked loose. That is a known and sometimes repairable fault — press gently, and stop if the picture worsens.
Update the firmware
Rarely the cause, occasionally the fix, and free to try before committing to a repair.
If the panel or the driver boards have failed, the repair cost frequently approaches the price of a comparable new television, because the panel is most of what you paid for. Get a quote before agreeing to anything, and be aware that panel replacement is almost never worth it on a set under about 55 inches.
What can be worth repairing
Not everything internal is terminal. A failed T-Con board is a relatively inexpensive part and a common cause of vertical banding. Loose ribbon connections can sometimes be reseated. Both are jobs for a repair technician, and both are worth getting quoted before writing the television off — ask specifically whether the fault is the panel itself or a board, because the answer changes the economics entirely.
Frequently asked questions
Can lines on a TV screen fix themselves?
Occasionally, if the cause is a loose connection or a temporary driver fault. Lines caused by a damaged panel do not improve and generally spread over time.
Does a cracked screen always show lines?
Not always immediately. Impact damage can start as a small blotch or a single line and spread over days or weeks as the layers separate further.
Is a vertical line covered by warranty?
If the set is within its warranty period and there is no physical damage, yes, this is normally a covered manufacturing fault. Contact the manufacturer before any third-party repair, which would void it.
Why do lines appear only after the TV has been on a while?
Heat expansion affecting a failing solder joint or connector. It is a genuine hardware fault and it typically worsens over months.
Open the TV’s menu first. If the lines are there too, you can stop testing cables and start getting quotes.
