LG TV No Signal: Complete Diagnostic, Fixes & When to Repair or Bin It
You turn on your LG TV and there it is. “No Signal.” You check the cable, you check the box, everything looks fine, and the message won’t go away.
Here’s the thing most people get wrong: they assume the TV has failed. In reality, “No Signal” means the TV isn’t receiving a valid signal on the selected input. It doesn’t mean the TV is broken — it means the signal chain, from the source device to the TV, has been interrupted somewhere. And in the vast majority of cases, the fault is a cable, an input setting, or an HDCP handshake issue. All three are free or cheap to fix.
Only in rare cases is the fault in the TV itself, and even then it’s usually a board rather than the panel. A failed panel doesn’t cause “No Signal” — so if you’re seeing that message, the panel is almost certainly fine.
This post walks through the signal chain in order, tells you how to isolate the fault, and shows you how to tell a port fault from a source fault from a board fault.
For the full index of LG TV faults — sound, power, picture, remote, and connectivity — see LG TV Problems: Troubleshooting Guide to Every Common Fault →
Quick Checks Before You Open Anything
Run through these first. They cost nothing, and they resolve the large majority of “No Signal” complaints.
Is the TV on the right input? Press the input button and check the selected input matches the port the source is actually plugged into. This sounds trivial and it’s one of the most common causes.
Is the source device actually on? A set-top box, console, or streaming stick in standby produces no signal, and the TV correctly reports no signal. Check the source’s own power light.
Reseat both ends of the HDMI cable. Unplug at the TV and at the source, then push both fully home. A partially seated connector is a very common cause.
Try a different HDMI cable. This is the single fastest test. HDMI cables fail more often than people expect — cheap ones especially.
Try a different HDMI port on the TV. If another port works, the first port has failed.
Try the source on another TV. If it works there, the fault is the TV’s port or board. If it doesn’t, the fault is the source or its cable.
Does the TV’s own menu display? If you can see the TV’s menu and settings but the source shows no signal, the panel and picture processing are fine — the fault is in the signal chain.
Did it start after a device change or firmware update? That points to HDCP or a resolution mismatch, both covered below.
If none of those resolve it, work through the faults below in order.
1. Loose or Faulty HDMI Cable
Why it causes “No Signal”: HDMI cables carry the signal, and they fail more often than people assume. Connectors work loose, contacts oxidise, and a cable that works fine on one device can fail on another — particularly if it’s an older or cheaper cable that can’t sustain the bandwidth a newer source demands.
This is the most common cause by far, and the cheapest to fix.
Symptoms:
“No Signal” on one input
Picture appears for a second, then “No Signal” returns
“No Signal” after switching inputs or moving the TV
“No Signal” only on certain devices
How to test it:
Reseat both ends first — unplug at the TV and at the source, then push both fully home. If that doesn’t fix it, swap in a different HDMI cable. This is the fastest test in the whole diagnostic, and it resolves a large share of cases on its own. If a different cable works, the original was the fault.
Cost: $5–$20 for a replacement cable.
Repair or Bin? Repair. Cheapest fix on the list.
2. Wrong Input Selected
Why it causes “No Signal”: The TV is showing an input that nothing is connected to. The source is plugged into HDMI 2 but the TV is set to HDMI 1, so the TV is correctly reporting that it’s receiving no signal on the selected input.
Symptoms:
“No Signal” after the TV was used by someone else
“No Signal” after switching inputs
The source’s own power light is on
The picture returns briefly when you cycle inputs
How to test it:
Press the input button on the remote and check which input is selected. Look at the back of the TV and confirm the cable is in that port. If not, select the correct input — or move the cable to match. Worth also checking the source’s own input setting if it has one.
Cost: $0.
Repair or Bin? Repair. Free, and more common than people admit.
3. Source Device Powered Off, In Standby, or Faulty
Why it causes “No Signal”: If the source isn’t producing a signal, the TV correctly reports no signal. The TV may be entirely healthy while the set-top box, console, or streaming stick is in standby, crashed, or faulty.
Symptoms:
“No Signal” only on certain devices
“No Signal” on one source but another source works
The source’s power light is off or showing standby
The source works on another TV
How to test it:
Check the source device’s power state first. Then power cycle it — unplug it, wait 30 seconds, plug it back in. Test the source on another TV if you can. If it produces a picture there, the source is fine and the fault is on the TV side. If it doesn’t, the source is the fault.
Cost: $0 to power cycle.
Repair or Bin? Repair. Free, and it’s the source that needs attention, not the TV.
4. Failed HDMI Port
Why it causes “No Signal”: HDMI ports can fail — the internal pins bend if a cable is yanked, or the port’s connection to the board degrades. When one port fails, that input shows no signal while the others work normally.
Symptoms:
“No Signal” on one input only
The same source works on a different port
The port feels loose, or the cable wobbles in it
Visible damage or a bent pin inside the port
How to test it:
Move the cable to a different HDMI port on the TV and select that input. If the picture appears, the original port has failed. Inspect the failed port with a torch for bent pins or physical damage. Don’t attempt to straighten pins yourself — they break easily and a damaged port can short.
Cost: $40–$90 for an input board, if the port is board-mounted.
Repair or Bin? Repair on a TV with spare ports — use another one. Board replacement on a TV under five years old if you need the port back.
5. HDCP Handshake Failure
Why it causes “No Signal”: HDCP is the copy protection protocol that runs between the source and the TV. Both devices have to agree on it before any picture is displayed. When the handshake fails — because the cable doesn’t support the required HDCP version, or the source needs a firmware update — the TV shows “No Signal” or a black screen.
This is one of the most common causes of “No Signal” after a device change or a firmware update, and it’s frequently misdiagnosed as a broken TV.
Symptoms:
“No Signal” after connecting a new device
“No Signal” after a firmware update on the TV or the source
Sound works but no picture
The TV detects the source but shows a black screen
The message appears only with one particular device
How to test it:
Try a different HDMI cable first — an older cable may not support the HDCP version the source requires. Then power cycle both devices in the right order: unplug the TV and the source, plug the source back in, let it boot, then plug the TV back in. That sequence forces a fresh handshake. Check the source for a firmware update. If the fault appeared right after a TV firmware update, a factory reset or a firmware rollback is the next step.
Cost: $0 to $20 for a cable.
Repair or Bin? Repair. Free or cheap, and it’s not a hardware failure.
6. Resolution or Refresh Rate Mismatch
Why it causes “No Signal”: If the source outputs a resolution or refresh rate the TV can’t handle, the TV may show “No Signal” rather than a corrupted picture. This happens when changing devices, after a source firmware update, or when a console or PC is set to an output mode the TV doesn’t support.
Symptoms:
“No Signal” only at certain resolutions
“No Signal” after changing a source’s display settings
“No Signal” after a source firmware update
The picture appears briefly then drops
How to test it:
Connect the source to a TV or monitor that definitely supports its output, and lower the resolution or refresh rate in the source’s settings. Then reconnect it to the LG TV. On a PC or console, safe mode or a low-resolution boot often lets you change the setting. If the picture appears at the lower setting, the original output mode was the problem.
Cost: $0.
Repair or Bin? Repair. Free setting change.
7. Failed Main Board or Input Board
Why it causes “No Signal”: If the main board’s input processing has failed, the TV can’t read the signal from any input — so every port shows “No Signal” even though the cables and sources are good.
Symptoms:
“No Signal” on every input
Every cable and every source tests good on other devices
No picture from any source, though the TV’s own menu may still display
Other functions affected — apps, sound, or settings
How to test it:
This is the diagnosis of elimination. If every cable is known-good, every source works on another TV, every port has been tested, and the input selection is correct — and there’s still no signal on any input — the main board or input board has failed. Inspect the board for visible damage, though confirming it usually means swapping the board.
Cost: Input board $40–$90. Main board $60–$150.
Repair or Bin? Repair on a TV under five years old. On an older set, weigh the cost against a new TV.
8. Firmware Fault
Why it causes “No Signal”: Occasionally a firmware update introduces an input detection bug or an HDCP handling fault. The hardware is fine; the software is misbehaving.
Symptoms:
“No Signal” appeared immediately after a firmware update
The fault is intermittent rather than constant
Some inputs work and others don’t, with no pattern
The message appears on inputs that previously worked
How to test it:
Check whether the fault started on the same day as a firmware update. Try a factory reset — Settings → All Settings → General → Reset to Initial Settings. If the signal returns after the reset, the fault was the software. If it returns and then fails again after the next update, contact LG support about a rollback.
Cost: $0.
Repair or Bin? Repair. Free, and it resolves software faults.
Repair vs Replace: The 50% Rule
If the repair costs more than 50% of the price of a new equivalent TV, replace it.
Typical repair costs:
Fault Typical cost DIY-friendly?
Wrong input, source powered off $0 Yes
HDCP handshake, resolution mismatch $0 Yes
HDMI cable $5–$20 Yes
Input board $40–$90 Partly
Main board $60–$150 Partly
Failed panel Not a cause of “No Signal” —
New TV cost: $300–$1,500 for LCD ranges; OLED sets run higher.
When to repair:
The fault is a cable, input setting, HDCP, or resolution issue — which covers most cases
TV is under 5 years old with a main board or input board fault
Repair cost is under half the new TV cost
When to bin:
TV is over 5 years old with a main board fault
Repair cost approaches half the new TV cost
Multiple faults at once
The reassuring point: “No Signal” is one of the few LG TV faults where the panel is definitively not the cause. Whatever the outcome, you’re not looking at a terminal repair.
What You Can Safely Do Yourself
Safe DIY checks and repairs:
Confirm the input selection matches the port in use
Check and power cycle the source device
Reseat both ends of the HDMI cable
Swap in a different HDMI cable
Move the cable to a different HDMI port
Test the source on another TV
Power cycle both devices in the correct order to force an HDCP handshake
Lower the source’s resolution or refresh rate
Factory reset for a firmware fault
Technician required:
Input board replacement
Main board replacement
HDMI port repair where the port is soldered to the board
Any repair involving the power supply
Safety note before you open the TV: unplug it and wait at least 10 minutes before removing the back panel — 30 minutes on larger sets. The power supply capacitors store lethal voltage even when unplugged. If your TV is under warranty, opening it may void coverage. And if you’re not comfortable working with high-voltage electronics, stop.
FAQ
Why does my LG TV say “No Signal”?
The most common cause is a loose or faulty HDMI cable, or the TV being on the wrong input. Swap the cable and confirm the input matches the port before anything else.
Why does my LG TV say “No Signal” on every input?
If every input shows “No Signal”, and every cable and source tests good, the main board’s input processing has failed.
Why does my LG TV show “No Signal” after a firmware update?
This is usually an HDCP handshake failure or a resolution mismatch introduced by the update. Check the source device settings and consider a factory reset or firmware rollback.
Why does my LG TV show “No Signal” only on some devices?
This points to a source device issue, a cable that doesn’t support the required resolution or HDCP version, or a specific port fault.
Why does my LG TV show “No Signal” but the sound works?
The audio and video paths can fail separately. This usually points to an HDCP handshake failure or a resolution mismatch — the TV is receiving audio but rejecting the video signal. Try a different cable, then power cycle both devices in order.
Why does my LG TV show “No Signal” when the cable is fine?
Check the input selection first, then try a different port on the TV, then test the source on another TV. If all three pass and the fault remains, it’s an HDCP or resolution issue, or the main board.
Is it worth repairing an LG TV that shows “No Signal”?
Usually yes, and often it’s free. A cable, input, or setting fix costs nothing. If the main board has failed, repair is worth it on a TV under five years old.
Where to Go Next
This post has covered the full signal chain and the decision framework for repair versus replacement. Depending on your situation, one of these is your next step:
If you’ve swapped the cable, tested the ports, checked the input, and the message persists, the dedicated guide walks the signal chain in order — input and cable testing, HDMI port testing, source device isolation, HDCP handshake diagnosis, resolution and refresh rate checks, and main board diagnosis — with the repair threshold for each component.
Get the LG TV No Signal guide — $3.95 →
If you’re getting a picture but no audio, that’s a different fault — the audio chain rather than the signal chain.
Get the LG TV Has No Sound guide — $3.95 →
If the TV powers on with sound but the screen stays black, that’s a backlight fault — and the torch test will confirm it in seconds.
Get the LG TV Backlight Not Working guide — $3.95 →
If you want the full LG TV fault reference in one place, the LG TV Fault Diagnosis Guide covers every common fault — picture, sound, power, apps, and connectivity.
Get the LG TV Fault Diagnosis Guide — $7.95 →
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