TV keeps restarting or turning on and off — repair in Riga
If your TV periodically switches off and back on by itself, gets stuck in an endless reboot cycle or dies a few seconds after powering up, the fault most often sits in the power board, overheating protection or a firmware crash. At the SATER service centre on Silmaču iela 6 we have been diagnosing and repairing these failures across all brands since 1993.
The power supply system of a television is one of its most heavily loaded assemblies — it provides multiple voltage rails (standby 5 V, mainboard 12 V, LED driver 24–200 V depending on panel size) and each rail is regulated by a dedicated PWM controller with its own filtering network. In Samsung and LG sets the power board is usually a separate PCB carrying a BN44 or EAY series part number, while Sony and Philips often combine the power supply and LED driver on a single board. The single most common cause of power cycling is electrolytic capacitors that have lost capacitance or bulged — their ESR (equivalent series resistance) rises, causing voltage ripple that the protection circuit detects and shuts the TV down. The second frequent culprit is the thermal protection sensor on the mainboard or power board: if ventilation is blocked or the thermal paste has dried out, the temperature hits the threshold and the set shuts down. A firmware crash loop (boot loop) typically manifests as the manufacturer logo appearing repeatedly — the TV begins loading the operating system, it crashes and the cycle restarts. We diagnose with an oscilloscope and ESR meter, identify the failed component and carry out a precise repair. We always agree a firm estimate before any work begins. The unit must be brought in person during opening hours.
Likely causes
- Capacitor failure on the power board (most common) — Electrolytic capacitors on the power board have lost capacitance or bulged — the output voltage becomes unstable and the protection circuit repeatedly shuts the TV down.
- Overheating protection triggering — Blocked ventilation, dried-out thermal paste or dust build-up causes the mainboard or processor to overheat — the thermal sensor shuts the TV off to prevent damage.
- Firmware crash loop (boot loop) — The operating system (WebOS, Tizen, Android TV) crashes during boot and the TV repeatedly shows the manufacturer logo without ever completing startup.
- Backlight driver short circuit — A burned-out LED or a driver board defect creates a short that the power board protection detects, shutting down the entire TV within seconds.
- Main board voltage regulator failure — A voltage regulator on the mainboard cannot deliver a stable supply to the processor or memory — the TV starts up but loses power after a few seconds.
What you can check yourself
- Unplug the TV for 10 minutes, hold the power button for 30 seconds to fully discharge the capacitors, then power on.
- Make sure the ventilation openings are not blocked — leave at least 10 cm clear on every side and vacuum away dust.
- Disconnect all external devices (HDMI, USB) and try powering on the TV with nothing attached — an external device can sometimes trigger a CEC boot loop.
- If the TV shows the manufacturer logo and then restarts, try entering service mode with the manufacturer remote key combination to perform a firmware recovery.
When to bring it in
If after these checks the TV still power-cycles or shuts off, professional bench diagnostics are needed. We test every capacitor and voltage regulator on the power board with an oscilloscope and ESR meter, measure the output voltage on all rails and check the LED driver chain. Failed capacitors or regulators are replaced with new parts of equal or higher specification. For firmware boot loops we recover the software through the service interface. All work carries a 3-month warranty. Bring the TV to Silmaču iela 6.
Fast on-site diagnostics. Repair warranty: 3 months.
Affected brands
Frequently asked questions
Why customers choose SATER
- From CRT to the latest Smart TVs. We repair televisions of every era — from tube sets to OLED and QLED.
- LED backlight diagnostics on a professional test rig. We pinpoint the faulty LED strip without replacing the entire panel.
- Samsung, LG, Sony parts in stock. Power boards, T-Con boards, LED drivers — key components always on the shelf.
- 30+ years of experience. The service centre has been operating since 1993.
- We serve all of Latvia. Our service centre is in Riga and we accept devices from anywhere in the country.