Set-top box shows no signal: black screen, channels gone, stuck on the logo

You switch the box on, the TV shows "No Signal" or a black screen, and every channel is gone. Or the box beeps and spins but stops at the manufacturer's logo. Boxes like these — set-top boxes, DVB-T2 receivers and network media players — reach our bench almost every week, and the good news is that the symptom points fairly precisely to which side is at fault: the TV, the cable, the antenna, or the box's own internals.

The main thing I want to say up front: before thinking about repair, separate three things that are easy to confuse. "No picture" is not the same as "no channels," and "won't turn on" is not the same as "stuck on the logo." Each has its own group of causes and its own check. We'll go through the symptoms in order — from the output (HDMI) to the input (antenna), then through boot and power to overheating.

We work with set-top boxes, network players and media players. Cameras, dashcams and GPS navigators we do not repair — we mention them here only so you don't confuse the cable or the input.

No HDMI picture — output, cable or the TV input

This is the most common "no signal." The front indicator on the box is lit, you may even hear it boot, but the TV shows a black screen or "No Signal." Before you open the case, rule out three simple things you can check yourself in 90% of cases.

First, the TV input. With the remote, switch Source / Input and make sure the exact HDMI port the cable is plugged into is selected. It sounds trivial, but half of "dead" boxes come back to life right here — someone had switched to the antenna input or a different HDMI number.

Second, the cable. HDMI cables die quietly: the contacts hold the salty air and damp that, near a window or on the floor in a Riga flat, is enough to bring on corrosion over a few years. The check is simple — move the same cable to another HDMI port on the TV and, if you can, try a different cable. If the picture appears with another cable, you've found the culprit.

Third, the box's output itself. If the cable is good, the input is correct, but there's still no picture on any TV, then the signal is gone on the box's side. Inside, that usually means either the HDMI output stage (knocked out by a voltage spike) or the power that keeps the screen output alive but not the rest of the board. You can't see that without instruments.

DIY boundary: the input, the port and the cable are home work. If the box stays black with two good cables and two TVs, what follows is soldering on the board, not a user job.

No signal / no channels — antenna and the receiver side

Here it matters to tell this apart from the previous case: the HDMI picture is there (you see the box's menu, logo, settings), but channels don't appear or the list stays empty after a scan. This is no longer an output question but an input one — the antenna signal or the DVB-T2 receiver chip.

Start with the physical chain from the antenna. Unplug and re-plug the coaxial lead at the box's antenna socket — make sure the centre conductor isn't snapped and the connector doesn't sit crooked. This is exactly where damp and the salty Baltic air do their work: the inside of the coaxial connector oxidises over the years, and the signal drops gradually until some channel "disappears."

Next, rescan the channels from scratch. In the box's menu find channel search / auto-scan and run a full scan, not the quick one. If channels used to be there but the list is empty or partial after a rescan, then the signal isn't reaching the receiver at a sufficient level. Causes by frequency: a weak or damaged antenna, a bad coaxial lead or connector, a splitter feeding too many outlets, or changes in the broadcast network itself.

Only once the antenna chain is ruled out does the receiver part itself remain. The DVB-T2 tuner in the box can degrade, especially after a thunderstorm, when a voltage surge enters down the antenna lead. The tell: another, known-good box on the same antenna finds channels, but this one doesn't.

• Antenna/feed cause (more common): the list is empty after a rescan; another box on the same lead also receives weakly.
• Tuner cause (rarer): another box on the same lead receives normally, but this one finds nothing — the receiver chip is gone.

DIY boundary: checking the lead, the connector and the rescan are on your side. Replacing the tuner chip on the board is a service job.

Stuck on the logo or cycling through restarts

The box powers on, the manufacturer's logo or a boot animation appears — and stays there. Or it hangs halfway, switches off and starts again, over and over (boot-loop). This is almost always a firmware/memory or power story, not HDMI.

First rule out the simplest thing — a full power disconnect. Pull the power plug from the box (don't just switch it off with the remote), wait about two minutes for the internal capacitors to discharge, and plug it back in. Surprisingly often this pulls the box out of a frozen boot, if the cause was a one-off software glitch.

If the manufacturer allows it, the next step is a factory reset — usually through the menu or a button combination at power-on. This wipes corrupted settings and accounts, so do it deliberately. Some media players also offer a firmware update from a USB stick per the manufacturer's instructions — if the box reaches the menu at all.

But there's a boundary where you stop. If the logo hangs again even after a reset, or the boot-loops start ever faster, there are usually two causes: the internal flash memory (eMMC or flash) has worn out and no longer holds the system, or the power doesn't hold a stable voltage at boot and the board restarts itself. Both are bench work — the first needs the memory rewritten or replaced, the second a repair of the power stage.

DIY boundary: the power cycle and the factory reset are safe. Memory and power repair are not.

Won't turn on at all (adapter and power input)

A completely dark box — no indicator lit, no reaction at all. Before you mourn the box itself, here's the good news: the most common cause of a "dead" box is not the box but the external power adapter. It's a cheap, easily replaced part, and we see it very often.

External adapters wear out faster than the box itself: inside they have small capacitors that, in the heating season of Riga flats and with the voltage dips in older buildings, gradually run down. The result — the adapter no longer delivers its rated voltage, and the box either won't turn on or turns on and drops out at once.

What you can check yourself:

1. Another socket and extension lead. Rule out the socket itself — plug straight into the wall, not through an overloaded extension lead.
2. The plug at both ends. Make sure the small DC plug sits firmly in the box's socket and the lead at the plug isn't broken — it's often bent behind furniture.
3. The adapter's markings. The output voltage and polarity are printed on the adapter's body. If you have a visually identical adapter with exactly the same output, try it — but only with fully matching parameters.

If the box still won't live with a known-good, correct adapter, the problem is inside — the power input socket (worked loose from frequent plugging) or the internal power stage on the board. That is already a service job.

Warning: never plug in an adapter with a higher voltage or wrong polarity "to try" — it kills the board instantly. If you aren't sure of the parameters, don't plug it in.

DIY boundary: the socket, the lead, the plug and a check with an identical adapter — yes. Re-soldering the power socket and repairing the internal stage — service.

Overheats and then freezes

A separate, telltale symptom: the box starts up fine, but after half an hour or an hour the picture freezes, the sound cuts out, or the box restarts on its own. After cooling down it works again — and the cycle repeats. This is classic overheating, and you can name it fairly precisely from this "works cold, dies warm" pattern alone.

Most boxes and media players cool passively — through ventilation slots in the case. Over the years these clog with dust, and if the box sits in a closed TV shelf or on a warm receiver, the air doesn't circulate at all. The processor overheats, and protection either throttles it or shuts it down.

What you can try yourself:

• Free up the ventilation. Move the box to an open, cool surface — not on another device, not in a closed niche. Leave free space above and around it.
• Clear the slots. With a can of compressed air, blow the dust out of the ventilation slots (switched off and unplugged).
• Watch whether it changes. If the freezing recedes on a cool, open surface, cooling was the cause and you've solved it.

If a clean, open box still freezes after warming up, the cause is deeper: inside, the power-stage capacitors are usually worn (warm, they lose capacitance and the voltage "drifts") or the thermal paste under the processor has dried out. Both call for opening it up and replacing parts on the bench.

DIY boundary: ventilation and dust cleaning are yours. Replacing capacitors and thermal paste — service.

Worth repairing or replacing? (decision table)

A fair question, since some boxes are cheap and not every fault is worth the bench. Here's how we ourselves look at it after an inspection. The value of some media players and network boxes lies not only in the hardware but in saved profiles, accounts and a library — "just buy a new one" isn't always simple.

We don't promise a repair over the phone and we don't buy parts "blind." We run a fast on-site diagnostic — so you know whether the bench makes sense for your particular box before we start anything.

For more on what we work with in this category — network players, set-top boxes, receivers — read the video equipment repair page. If the problem turns out to be not in the box but in the Smart TV's own network, the article on how to connect a Smart TV to Wi-Fi will also help.