TV HDMI port not working: one or all showing No Signal

You plug a set-top box or console into the television, switch to that HDMI input — and the screen stays black with "No Signal". Meanwhile the TV's own apps and, say, the aerial channels show fine. This is a routine sight at our bench, and the good news is that in nine cases out of ten you can narrow the cause down at home in a couple of minutes, before there's any talk of repair.

The key is not to jump to "the TV is dead". Just as often the culprit is the cable, the source device, or a broken HDMI-CEC/HDCP handshake. We work through it below in exactly the order we separate causes at the service centre: from the cheapest to the most expensive.

Which input is silent, which works — the first clue

The first thing to establish: is the problem in one specific HDMI socket, or in all of them. That alone halves the diagnosis.

Move the same cable with the same connected device into each HDMI port in turn — HDMI 1, HDMI 2, HDMI 3 — and each time select that exact input in the menu. Note what happens.

If the TV's own apps (YouTube, Netflix) and the aerial picture work but HDMI doesn't, we already know the screen, panel and power supply are alive — we focus on the HDMI path itself.

Rule out the cable and the source device

Most "dead ports" turn out to be live ports with a dead cable or a frozen source. We always check these two first, because they take a couple of minutes by hand.

• Swap the cable. Take a different HDMI cable — ideally a shorter one — and connect the same device to the same port. Kinked, repeatedly yanked, or cheap cables break exactly along the differential pairs that carry the picture; the video then disappears even though the cable looks intact from the outside.
• Swap the source device. Connect a different device to the same port with the same cable — a set-top box, a laptop, a console. If the other device shows a picture, the port is fine and the source is to blame.
• Check the source output. Set-top boxes and consoles sometimes "stick" at the wrong resolution, or the HDMI output simply hangs. Fully disconnect the source from mains for a minute, not just switch it off with the remote, and power it back up.
• Full power cycle. Unplug the TV from the wall for a minute — that drains the capacitors and the HDMI interface boots from scratch. This fixes a surprising number of "the picture suddenly vanished" cases.

Note the result. Only once you are sure the cable and source are good does it make sense to suspect the TV itself.

The HDMI-CEC handshake and HDCP (no signal even though the device is on)

This is the most deceptive scenario: the source device is clearly on, its indicator is lit, yet the TV stubbornly shows "No Signal". Often neither the port nor the cable is at fault — the digital handshake has broken down.

Before sending a picture, HDMI devices "talk" to each other: they agree on resolution, frame rate, and content protection (HDCP). If that conversation fails, the picture simply isn't sent, and you see a black screen.

• HDCP handshake. Streaming boxes and consoles demand HDCP protection. If the TV and source can't agree, there's no picture — often after swapping cables or changing inputs. A full mains disconnect of both devices and powering them back up in the right order (TV first, then source) usually restores it.
• CEC conflict. HDMI-CEC lets devices control each other from one remote — Samsung calls it Anynet+, LG SIMPLINK, Sony BRAVIA Sync, Philips EasyLink. Sometimes CEC "sticks" and confuses input switching. Try turning CEC off in the TV menu for a while and checking whether the picture returns.
• Safe restart sequence. Switch off both devices, unplug the HDMI cable and the power of both devices, wait a couple of minutes, plug the cable back in, and switch on the TV first, then the source.

If the picture appears for a moment and disappears, or flickers along with an HDCP warning, that is still a handshake cause, not hardware — so this step is worth doing carefully.

One dead HDMI port — connector vs. board

If the swap test showed that only one socket is silent while the rest show fine, you are almost certainly looking at local, physical damage in that exact port. A whole "burnt-out" board almost never causes it.

At the bench we most often see two reasons:

• A cracked solder joint. The HDMI socket is soldered to the board with fine contact legs. From repeated cable-pulling and thermal cycling, one or more solder points crack. The contact becomes unstable — there's a picture when the cable is turned at one angle, and it vanishes when you nudge it.
• A damaged connector. If the cable was plugged in or yanked out while the TV was on, or forced into the socket crooked, the socket's internal contacts can bend or snap. The port then stays dead even with a new cable and a working source.

This is not a home fix. The correct repair is desoldering and resoldering the HDMI socket, or replacing the damaged socket — that needs a hot-air station, flux, and a gentle temperature profile so the neighbouring components on the board aren't harmed. Trying to "coax" it with a soldering iron at home more often kills the adjacent traces than fixes the port.

All HDMI ports dead — HDMI/main board

If every single HDMI input is silent while the TV's apps and aerial work, the problem is no longer in one socket — it's in the HDMI signal-processing stage on the board.

In most modern televisions, the HDMI inputs are served by one shared HDMI/switch chip or the main processor itself on the main board. If that stage is damaged, all the ports fail at once, while the rest of the TV's functions — which take a different path — keep working.

Typical causes we record:

• a surge hit that knocked out the HDMI input protection;
• a partial failure of the processor or HDMI chip;
• contact loss on the board traces from moisture and corrosion.

Here diagnostics means a board check — measuring the power lines and the signals of the HDMI chip and processor, to work out whether replacing a single component is enough or the whole board has to be changed. We run a fast on-site diagnostic; without opening the board there's no honest way to name it.

Why ports die in Riga (surges, moisture, "hot" plugging)

HDMI ports rarely die on their own — they usually get help. Three causes we see especially often in Riga flats:

• Surges and storms. A hit can come in not only through the socket, but also along the aerial cable and over HDMI from another device. Older Riga buildings have voltage swings and a "floating" earth between devices — a single transient is enough to knock out the sensitive HDMI input protection.
• Baltic moisture and salt air. In high humidity and coastal saltiness, a film of oxide and corrosion builds up over time on the board traces and socket contacts. In the heating season the dry, hot air adds thermal cycling on top, which only worsens cracks in the solder joints.
• "Hot" plugging. The most common user-caused damage — plugging and pulling a cable while the TV and source are on. A potential difference between two live devices can knock out the socket contacts. The habit of always cutting power before switching HDMI lengthens a port's life.

Across the typical 4–6 year ownership window, these three factors together explain most of the "suddenly dead" HDMI ports brought to us.

Symptom → cause → action

This table gathers the above into one diagnostic tree. Go from top to bottom — the first row that matches your situation points to the next step.

The sections on the two most expensive scenarios — one dead port and all dead ports — are exactly the line beyond which a do-it-yourself attempt does more harm than good. The cable, source, and power-restart tests are safe home steps; socket soldering and board repair are not.

For more on how we separate hardware faults from settings, see the TV repair page. Related symptoms are covered in the articles on no sound through HDMI ARC and TV screen problems.