LG TV No Signal
No Signal On Every Input
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, a “No Signal” message 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.
In the vast majority of cases, the fault is a cable, an input setting, or an HDCP handshake issue. All three are free 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.
This guide 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.
Why Your LG TV Shows No Signal
A “No Signal” message means the TV isn’t receiving a valid signal on the selected input. The signal chain has four links, and any one of them can fail:
Loose or faulty HDMI cable — the most common cause by far. Cables work loose, connectors oxidise, and cables that work on one device can fail on another.
Wrong input selected — the TV may be on a different input from the one the source is plugged into.
Source device powered off or in standby — if the source isn’t producing a signal, the TV correctly reports no signal.
Failed HDMI port — on the TV or the source device. Test with a different port to confirm.
HDCP handshake failure — the copy protection protocol between devices. When it fails, the TV shows “No Signal” or a black screen.
Resolution or refresh rate mismatch — if the source outputs a resolution the TV can’t handle, the TV may show “No Signal.”
Failed main board — if every input shows “No Signal” and every cable and source tests good, the main board’s input processing has failed.
Firmware fault — occasionally, a firmware update introduces an input detection bug.
Common Symptoms
“No Signal” message on one input
“No Signal” message on every input
TV detects the source but shows a black screen
Picture appears for a second, then “No Signal” returns
“No Signal” after switching inputs
“No Signal” only on certain devices
“No Signal” after a firmware update
“No Signal” only at certain resolutions
Sound works but no picture
What Causes These Faults
Cable failure. HDMI cables fail more often than people expect. They work loose, the connectors oxidise, and cheaper cables are especially prone to failure.
HDCP handshake failure. HDCP is the copy protection protocol used between devices. When the handshake fails, the TV shows “No Signal.” This is often caused by a cable that doesn’t support the required HDCP version, or by a source device that needs a firmware update.
Resolution mismatch. If the source device is outputting a resolution or refresh rate the TV can’t handle, the TV may show “No Signal.” This happens when changing devices, or after a source firmware update.
Port damage. HDMI ports can fail if the cable has been yanked, or if the port’s internal pins have been bent. Test with a different port to confirm.
Main board failure. If every input shows “No Signal” and every cable and source tests good, the main board’s input processing has failed.
What the Guide Covers
This diagnostic guide walks through the signal chain in order:
Input and cable testing
HDMI port testing
Source device testing
HDCP handshake diagnosis
Resolution and refresh rate checks
Main board and input board diagnosis
Firmware troubleshooting
Repair-or-replace thresholds
What You’ll Learn
You’ll learn how to confirm the fault is a signal issue and not a panel issue, how to test each input and cable in isolation, and how to identify a failed HDMI port.
You’ll learn how to diagnose HDCP handshake failures, which are one of the most common causes of “No Signal” after a device change or firmware update.
You’ll also learn how to test the source device independently, how to check resolution and refresh rate settings, and how to decide whether the main board or input board needs replacing.
Repair or Bin?
Most LG TV “No Signal” faults are free to fix. A loose cable, wrong input, or source setting accounts for the majority of cases. An HDMI cable is typically $5 to $20.
Where the maths changes is the main board or input board. An input board is typically $40 to $90. A main board is $60 to $150. On a TV under five years old, both are worth repairing. On a TV over five years old, weigh the repair cost against the cost of a new set.
A failed panel is not a cause of “No Signal,” so if you’re seeing the message, the panel is almost certainly fine.
The guide includes a clear repair-or-replace threshold for each component.
Frequently Asked Questions
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 rolling back the firmware.
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.
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.
Get the Complete Guide
This guide gives you the full signal chain diagnostic, the HDCP troubleshooting steps, and the repair cost reference.
Get the LG TV No Signal Guide
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