HDMI no signal on a monitor or TV: what to check
A no signal message over HDMI rarely means a dead screen. Learn how to tell an input, cable, display mode or port problem apart, starting with free checks.
When a screen says no signal, most people decide the monitor or TV has failed. Usually it has not. The message actually proves the screen is powered on and working, because it is drawing that text itself. What it is telling you is that the HDMI port it is listening to is not receiving a picture it can use. The fault can be the input choice, the cable, the computer sending the picture, or the port. Each one can be checked separately.
Is the screen listening to the right port?
A monitor or TV with two or more HDMI ports only shows one of them at a time. If the cable is in the second port and the screen is set to the first, you get no signal even though everything else is fine. Press the input or source button on the remote or on the screen's own buttons and step through each port slowly. Some monitors search for an active input on their own, but many TVs do not, so this is the first thing to rule out.
The cable, its type and its length
An HDMI cable carries the picture as very fast electrical signals, plus a small handshake that lets the two devices agree on what to send. A plug that is half seated can lose that handshake while looking connected. Switch both devices off, pull the cable out at each end and push it in firmly. An older or basic cable may not carry enough data for a high resolution at a high refresh rate. Very long cables also weaken the signal. Swapping in a short, known-good cable settles this quickly.
The source may be asleep or sending elsewhere
The screen can only show what the computer, console or set-top box actually sends. A computer in sleep mode stops sending a picture, so press a key or move the mouse and wait a few seconds. On a desktop with a separate graphics card, the HDMI port on the motherboard is often switched off once the card is fitted, so the cable must go into the card's port lower down. A laptop may also be set to show its picture on its own screen only.
Laptop display mode, resolution and refresh rate
A laptop connected to an outside screen can duplicate its display, extend the desktop across both, or use just one of them. If it is set to its own screen only, the outside monitor gets nothing and reports no signal. Change the mode in the display settings or with the display-mode shortcut key. A different problem appears when the computer sends a resolution or refresh rate the screen cannot accept. Many screens then show no signal or out of range, even though a picture is being sent.
- Blank on every input: check the cable and the source device first.
- Picture on another screen: lower the resolution and refresh rate, then reconnect.
- Laptop only: switch the display mode to duplicate or extend.
When the port itself is damaged
HDMI ports have rows of thin contacts that can bend or loosen when a cable is pulled at an angle or the screen is moved with it attached. A damaged port often gives a picture that cuts in and out when the plug is touched, or works only when the plug is held at a slant. Try a second HDMI port on the screen and a different output on the source. If only one port fails with several cables, that port is the fault and needs a technician.
What to try, in order
- Press the input or source button and step slowly through every HDMI port on the screen.
- Wake the computer or other source with a key press, then wait a few seconds for the picture.
- Switch both devices off, then unplug and firmly reseat the HDMI cable at both ends.
- On a desktop with a graphics card, move the cable from the motherboard port to the card's port.
- On a laptop, change the display mode to duplicate or extend in the display settings.
- Try a short, known-good HDMI cable and a different HDMI port on the screen.
- If one port fails with every cable and source, take the screen to a service centre to check it.
What to take from this
Start with the free checks, because most no signal messages come from the wrong input, a loose plug or a sleeping computer. If those are fine, change one thing at a time: the cable, then the port, then the source device. Whichever change brings the picture back tells you exactly where the fault was. Only when a single port fails with every cable and every source is it time to think about a repair.
Common questions
Why does my monitor say no signal when the HDMI cable is connected?
The screen is usually listening to a different input, the plug is not fully seated, or the computer is asleep and not sending a picture. Select the correct HDMI input first, then reseat the cable with both devices switched off. On a desktop, make sure the cable goes into the graphics card rather than the motherboard.
Why does my TV show no signal from my laptop over HDMI?
The laptop may be set to show its picture on its own screen only, so nothing reaches the TV. Change the display mode to duplicate or extend in the display settings. Also check that the TV is on the matching HDMI input and that the resolution the laptop sends is one the TV can accept.
Can a bad HDMI cable cause a no signal message?
Yes. A cable with a broken wire or a worn plug can lose the handshake between the two devices, and an older or very long cable may not carry enough data for a high resolution or refresh rate. Swapping in a short cable that you know works is the quickest way to rule the cable in or out.
