To find out whether an HDMI cable or port is faulty, change one part of the setup at a time: check the source and selected input, reseat the cable, try another HDMI port, swap in a compatible known-working cable, then cross-test the source and display. The component the problem follows is the likeliest suspect. A “No Signal” message alone does not identify the cause.
Start with power, input selection, and cable seating
Before testing hardware, confirm the source device is on and awake, and that the TV or monitor is set to the HDMI input matching the port in use. A cable box, receiver, or other source may also have its own input selection. Samsung lists device power and source selection among the first checks for a no-signal problem (Samsung US troubleshooting).
- Turn on the source device and wake it if necessary.
- Select the correct HDMI input on the display and, where applicable, on the source device.
- Unplug the HDMI cable at both ends, then firmly reconnect it.
- If you need to power-cycle the devices, Samsung UK advises disconnecting power from the TV and external device for at least 10 seconds. Reconnect power, then connect HDMI at the source first and the display second. The exact steps can vary by model (Samsung UK HDMI connection guidance).
Test the HDMI port and cable by changing one at a time
Try another input on the same display
Keep the source device and cable unchanged. Move the cable to a different HDMI input, select that input in the display menu, and check whether the picture appears. If the same setup works on the new input but repeatedly fails on the original one, the original input or its settings become more likely causes. This points to where the problem occurs in this setup; it does not, by itself, prove internal port damage. Samsung recommends trying another TV port and checking the port for visible damage or debris (Samsung Gulf port troubleshooting; Samsung UK guidance).
Look for visible damage or debris without inserting tools into the port. If the failure follows that input across repeat tests, note the result for the manufacturer or repair provider.
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Swap in a compatible, known-working cable
Return to the same source and display input, then replace only the cable. Use one known to work and compatible with both devices and the resolution and refresh rate you are trying to use. A cable that does not meet the connected devices’ specifications may not work reliably; Samsung UK recommends using a certified cable compatible with the devices (Samsung UK cable guidance).
If the replacement cable makes the same setup work, the original cable is defective or unsuitable for that signal. Samsung’s US guidance states, “If the issue is resolved, the original cable is defective” (Samsung US No Signal/Weak Signal troubleshooting). For 4K at 120 Hz, Samsung says the cable must be HDMI 2.1 and recommends confirming that it is certified. A new cable is useful when this test implicates the old one; it will not fix a damaged port or faulty source device.
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Cross-test the source and display
If changing the port and cable has not isolated the problem, test the devices against other equipment. Keep track of which parts you swap so you can tell whether the failure follows the source or the display.
- Try the original source on another display. If it produces a picture there, the original source can output video in that setup; investigate the first display, its input, or its configuration.
- Connect another source to the original display and input. If that source works, investigate the original source device or its output settings.
- Try several known-good combinations. If multiple sources and cables fail on one input but work on another, the first input or display is more suspect. If failures span several sources, cables, and inputs, the cause may be display configuration, source configuration, or more than one issue—not necessarily a single broken port.
Microsoft recommends trying an external monitor with a different system, while Samsung advises testing another external device. These cross-tests help narrow the fault to one side of the connection, but do not confirm which internal component has failed (Microsoft external-monitor troubleshooting; Samsung US troubleshooting).
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Interpret the results without overdiagnosing
| What changes the result | Likeliest next suspect | What the test tells you |
|---|---|---|
| The same setup works after replacing the cable | Original cable | Strong evidence that it was faulty or unsuitable for the signal. |
| The same source and cable work on another display input | Original input or its settings | The failure follows the original input in this setup; repeat the test and seek service if it persists. It does not prove internal damage. |
| A different source works on the same display and input | Original source device or its output settings | The display path can work with another source; troubleshoot the original source. |
| The original source works on another display | Original display, input, or display configuration | The source can output in the alternate setup; continue isolating the display side. |
| Several known-good cables, sources, and inputs still fail | Display or source configuration, or multiple issues | A no-signal result alone does not establish a single failed port; seek model-specific diagnosis. |
For Windows PCs, check output settings after hardware swaps
Once basic swaps have helped narrow the hardware, check the PC’s display output path. These steps can fix a Windows output or configuration problem; they are not proof that an HDMI port is physically damaged.
- Press Windows+P and choose the projection mode you intend to use.
- Temporarily disconnect docks, dongles, and adapters, then connect the display directly if possible. Try another PC output port if one is available.
- If the connection used to work and failed after a display-driver update, Microsoft lists rolling back or reinstalling the display driver among later troubleshooting options (Microsoft Windows external-monitor troubleshooting).
Use a TV’s built-in cable test only if your model supports it
Some Samsung TVs offer an HDMI cable test, but availability and menus vary by model; some models require a software update and older models may not include the feature. Samsung says its cited test is designed for cables shorter than 2 m and may not produce good results with longer cables. Check the manual for your exact TV and treat the test as one clue, not a universal cable or port diagnosis (Samsung picture troubleshooting).
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When to contact the manufacturer or arrange repair
Seek model-specific support when the result consistently follows one port or device—for example, a known-working source and cable work on another input but repeatedly fail on the suspect input—or when no tested combination works after the checks above. Samsung notes that a port may be damaged if its listed troubleshooting does not resolve the problem (Samsung Gulf HDMI-port guidance). Record which sources, cables, and inputs you tested and what happened; this gives support a clearer starting point. Service options and warranty conditions depend on the device, model, and country.
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