Safety first: Never open a TV’s back cover. Power boards can hold a dangerous charge even after unplugging. Leave internal work to a qualified technician.
Common Symptoms and Likely Causes
TV faults often have a cheaper cause than “the screen is dead”. These are the most common:
| Symptom | Common causes | Who should handle it |
|---|---|---|
| Sound works, screen dark | Backlight LED strips or backlight driver, sometimes a main board fault | Technician (try the flashlight test first) |
| Won’t turn on, standby light blinks | Power supply board, main board, or a backlight short triggering protection | Technician |
| Vertical or horizontal lines | Loose or damaged ribbon cable, T-con board, or panel fault | Technician |
| Washed-out or inverted colours, double image | T-con board or cable fault, picture settings | Reset picture settings; repairs are technician work |
| Cracks, black ink-like patches | Physical damage to the LCD/OLED panel | Usually replacement — get a quote |
| No signal from one input | Source device, cable or input port fault | Test another cable and source first |
Safe First Checks Before You Book
These checks don’t require opening the TV and can narrow down the fault:
- Do the flashlight test
With the TV on and sound playing, shine a torch close to the screen in a dark room. If you can faintly see the picture, the panel is likely working and the backlight is the probable fault.
- Power cycle the TV
Unplug it for a few minutes, then plug it directly into a wall outlet (not an extension strip) and try again.
- Check the TV’s own menu
If the on-screen menu displays correctly but an input doesn’t, test a different cable or source device.
- Note the standby light pattern
Write down any blink pattern — some manufacturers use it to report a fault type.
When to stop: Don’t remove the back cover or try to repair boards yourself — capacitors on the power board can hold a dangerous charge after the TV is unplugged.
Backlight Fault vs. Panel Damage
A common misunderstanding — and occasionally an overcharging tactic — is treating a backlight fault as a dead panel.
Often repairable
Backlight failure
Sound and channel changes work but the picture is dark. If the flashlight test shows a faint image, the panel is usually fine and the LED backlight strips may need replacing. Ask whether all strips will be replaced, as the remaining ones are often the same age.
Physical damage
Cracked or damaged panel
Cracks, spreading black patches or bleeding colours point to panel damage. Replacement panels are often expensive or unavailable, and the cost can approach that of a new TV.
Board Repairs and Safe Transport
Most TVs contain a power supply board, a main board and a T-con (timing controller) board. If the TV needs workshop time, protect it in transit.
- Power supply board
Faults can sometimes be repaired at component level rather than replacing the whole board. Ask which option is being quoted and why.
- T-con board and cables
Lines, double images or odd colours are sometimes fixed by reseating cables or replacing the T-con board before a panel is condemned.
- Transport upright and padded
Flat panels can crack if carried flat or flexed. Ask how the TV will be transported, and use the original box if you still have it.
- Photograph the screen first
Take clear, dated photos of the screen and casing before the TV leaves your home, so any transit damage can be identified.
Questions to Ask Before You Book
Ask these before agreeing to a visit or collection:
Q1: “What is your diagnostic fee, and is it credited toward the repair?”
Get the answer before booking so there are no surprises.
Q2: “Do you replace the full backlight set or only failed strips?”
Replacing all strips generally reduces the chance of another failure soon after.
Q3: “Will you repair the board or replace it, and what does each cost?”
Understanding both options helps you compare quotes.
Q4: “How is the TV transported, and is it insured while with you?”
Get collection, return and any transit cover terms in writing.
Repair or Replace?
TV prices have fallen a lot, so compare carefully:
Compare with a new TV of similar size
If the repair costs a large share of a comparable new set — common for panel damage — replacement is usually better value.
Consider age and features
An older TV may lack current smart features, HDR or app support even after repair.
Check warranty and insurance
Retailer, manufacturer or credit-card extended warranty and home insurance may cover faults or accidental damage.
Recycle responsibly
If you replace the TV, use an electronics recycling scheme — many retailers and local authorities offer take-back.
Checklist Before You Pay
Display quality check
Before final payment- View a full-screen white and grey image to check for even brightness without dark patches or bright spots.
- Check for vertical or horizontal lines and colour problems on several types of content.
- Test every HDMI input you use, sound output, Wi-Fi and the remote control.
- Get an itemised invoice showing parts, labour and warranty terms, and inspect the casing for new damage.
Next steps
This guide is general educational information, not a diagnosis. Repair Guide does not perform repairs or recommend specific businesses. Always follow the manufacturer’s instructions and use a qualified technician for electrical, gas and refrigerant work.