TVs

No power, backlight, blink codes, lines on screen and boot loops.

15 field manuals · 55 error codes · 31 guides · 9 brands

Field service manuals

Manual · TV

LED/LCD TVs (all brands): field service manual

Flat-panel LCD TVs with LED backlight (edge-lit, direct-lit, mini-LED and QLED/QD-film sets), roughly 2010 to current. Board names and layouts vary by brand and series.

7 components7 common failuresSamsung, LG, Sony, TCL, Hisense, Vizio, Roku TV, All
Manual · TV

OLED TVs (LG, Sony, Samsung QD-OLED): field service manual

LG OLED (WOLED) sets ~2016 onward, Sony BRAVIA OLED, Samsung QD-OLED (S90/S95 family). Menu names vary by year.

4 components6 common failuresLG, Sony, Samsung
Manual · TV

Smart TV software & connectivity (Roku TV, Google TV, Tizen, webOS, Vizio SmartCast): field manual

Smart platforms on US TVs: Roku TV (TCL, Hisense and others), Google TV / Android TV (TCL, Sony, Hisense), Samsung Tizen, LG webOS, Vizio SmartCast. Menu paths change between software versions.

3 components6 common failuresRoku TV, TCL, Hisense, Sony, Samsung, LG, Vizio
Manual · TV

TV wall-mount & installation basics: field manual

Flat-panel TVs with VESA mounting holes on drywall over wood studs, masonry walls, and basic cable/power concealment in US homes.

3 components3 common failuresAll
Manual · TV

TCL 4-Series Roku TV (S435 / S455): quick sheet

TCL 4-Series Roku TVs: S435 (2021 line, e.g. 43S435, 55S435, up to 85 in) and S455 (2022 line, e.g. 43S455, 55S455). Earlier S4-family sets (S405/S425 era) use the same design idea but different boards and strips (TCL product pages, Tom's Guide review, DisplaySpecifications launch note).

6 components4 common failuresTCL
Manual · TV

TCL 5-Series QLED (S535 / S546 / S555): quick sheet

TCL 5-Series quantum-dot (QLED) sets: S535 Roku TV (2020), S546 Google TV (Google TV version of the same generation) and S555 Roku TV (2022). Sizes roughly 50-75 in (TCL product pages; Reviewed, Tom's Guide and Tech Steve reviews).

6 components4 common failuresTCL
Manual · TV

Hisense U6 ULED (U6H / U6K / U6N): quick sheet

Hisense U6-series ULED Google TVs: U6H (2022), U6K (2023), U6N (2024). North American models run Google TV (FlatpanelsHD, TechRadar, Tech Steve, Best Buy listing).

6 components4 common failuresHisense
Manual · TV

Hisense U7 ULED / Mini-LED (U7H / U7K / U7N): quick sheet

Hisense U7-series Google TVs: U7H (2022), U7K (2023), U7N (2024, mini-LED). North American models run Google TV (Hisense announcements via FlatpanelsHD; TechRadar; tvsbook comparison).

6 components4 common failuresHisense
Manual · TV

Samsung Crystal UHD TU7000 / CU7000: quick sheet

Samsung Crystal UHD entry 4K sets: TU7000 (2020, e.g. UN55TU7000FXZA) and CU7000 (2023, e.g. UN55CU7000FXZA), sizes about 43-85 in. Model-year letter: T = 2020, C = 2023 (DisplaySpecifications, Micro Center, AV-iQ listings).

6 components4 common failuresSamsung
Manual · TV

LG OLED C-Series (C1 / C2 / C3 / C4): quick sheet

LG OLED C-Series 4K: C1 (2021, e.g. OLED65C1PUB), C2 (2022, OLED65C2PUA), C3 (2023, OLED65C3PUA) and C4 (2024, OLED65C4PUA); sizes 42-83 in by year (LG product page, LG C1 spec sheet, mounting and review references).

6 components4 common failuresLG
Manual · TV

Vizio V-Series and M-Series Quantum (2020-2023): quick sheet

Vizio V-Series 4K (e.g. V655-J09, 2021 'J' year) and M-Series Quantum (e.g. M65Q7-J01, 2021; 30 local dimming zones on 65 in). Year letter in the model: H = 2020, J = 2021, K = 2022, M = 2023 (Vizio M65Q7-J01 page; spec listings).

6 components4 common failuresVizio
Manual · TV

Sony BRAVIA X80K / X85K (and L-year successors): quick sheet

Sony BRAVIA 4K LED Google TVs: X80K and X85K (2022, e.g. KD-55X85K), with X80L/X85L (2023) as the following year. X85K: 120 Hz native on 55 in and up, X1 processor (Sony regional spec pages; retailer listings).

6 components4 common failuresSony
Manual · TV

Insignia / Toshiba Fire TV Edition (F30, C350 class): quick sheet

Fire TV Edition sets sold mainly by Best Buy and Amazon: Insignia F30 4K series (e.g. NS-50F301NA22 / NS-55F301NA22, and the NA24 year) and Toshiba C350 4K Fire TV. Board and strip designs vary by year suffix; Toshiba C350 board compatibility with Insignia is not confirmed (retailer parts listings, repair Q&A).

6 components4 common failuresInsignia, Toshiba
Manual · TV

Soundbars & home-theater audio basics: field manual

TV-connected soundbars with wired or wireless subwoofers, HDMI ARC/eARC and optical connections

2 components5 common failuresSamsung, LG, Vizio, Roku, All
Manual · TV

Projectors (lamp vs laser, lamp hours, overheating): field manual

Home-theater and business projectors with lamp, LED or laser light sources

3 components4 common failuresEpson, BenQ, ViewSonic, Optoma, All

Diagnostic guides · 27

Guide · TV

"No Signal" or HDMI input problems

Most no-signal calls are the wrong input, a bad cable, or a source device that is off or sending a format the TV can't show.

5 steps ~20 mineasy
Guide · TV

Apps freeze, crash or won't load

Separate network from app: test on a phone hotspot. One app failing is usually the app; all apps failing points to network or TV software.

4 steps ~30 mineasy
Guide · TV

Audio out of sync with picture (lip sync)

Check whether it's every source or one channel. Use the TV's AV sync / bypass controls, the soundbar's own delay, and PCM output.

4 steps ~20 mineasy
Guide · TV

Bluetooth / smart remote won't pair

Smart remotes use Bluetooth/RF for most keys and IR only for a few (often power). Fix batteries first, then reset and re-pair close to the TV sensor.

3 steps ~10 mineasy
Guide · TV

Factory reset and firmware update

Try a soft restart first, then a factory reset from menus, and if menus are unreachable use the hardware reset button (Roku TV). Update firmware afterward.

4 steps ~30 mineasy
Guide · TV

Firmware update or recovery from a USB drive (Samsung, LG)

Samsung and LG let you load the model's update file from a USB stick. The format and folder rules are strict; most failures are a wrong file, wrong folder or wrong format.

4 steps ~30 mineasy
Guide · TV

Flicker only in HDR / Dolby Vision or from one HDMI source

Usually the enhanced HDMI mode (LG HDMI Ultra HD Deep Colour, Samsung Input Signal Plus) with a cable, hub or source that can't hold the bandwidth.

3 steps ~20 mineasy
Guide · TV

Half of the screen dark

A dim half that still shows an image is usually backlight (strips or connector). A completely black side with no image points more to the T-con or ribbon. Answers vary by model.

4 steps ~90 minadvanced
Guide · TV

HDCP error, purple screen or protected content won't play

The HDCP handshake failed somewhere in the HDMI chain. Simplify the chain, reseat cables, power up in order, and confirm HDCP 2.2 for 4K/HDR.

2 steps ~15 mineasy
Guide · TV

LED backlight strip replacement (direct-lit LCD TVs)

On direct-lit sets the strips sit behind the LCD and optical sheets. The job is mostly careful handling: lift the panel by its frame, keep the sheets in order, replace the whole strip set by part number and test before closing.

5 steps ~120 minadvanced
Guide · TV

No sound from TV speakers

Most cases are mute/volume or the output still set to an external speaker. The built-in sound test separates TV speakers/amp from source problems.

4 steps ~20 mineasy
Guide · TV

OLED image retention or burn-in

Short-term retention usually clears on its own once the TV's automatic compensation runs at power-off. One manual refresh is the next step; if the ghost survives, it is permanent panel wear and the fix is a panel.

4 steps ~90 mineasy
Guide · TV

Picture flickering or dimming

Rule out picture settings (energy saving, ambient light sensor) and the source/cable first. Flicker on the TV's own menus points to backlight or power board.

4 steps ~30 minmoderate
Guide · TV

Picture too dark or dims on its own (energy saving / eco sensor)

Usually settings, not hardware: energy saving, eco/ambient light sensors and Eco picture modes. Rule these out before suspecting the backlight.

4 steps ~20 mineasy
Guide · TV

Roku TV / Fire TV: black screen but sound plays

First prove it isn't input or source (press Home, change input, remove devices). Then the flashlight test: a faint image means backlight failure.

5 steps ~30 minmoderate
Guide · TV

Sound but no picture (backlight / LED strip test)

The flashlight test tells you in one minute whether the panel is producing an image with no backlight. If you can see a faint image, the LED strips or LED driver are the likely fault; if not, look at T-con or main board.

4 steps ~90 minadvanced
Guide · TV

Soundbar or receiver has no audio over HDMI ARC/eARC

Almost always a settings or port problem: CEC off, ARC/eARC not enabled, soundbar on a non-ARC port, or the TV's audio format set to something the bar can't decode. Work through settings before suspecting hardware.

5 steps ~20 mineasy
Guide · TV

TV remote not working

Check batteries, then whether the remote is IR or Bluetooth/RF. Re-pair smart remotes; test IR remotes with a phone camera.

4 steps ~15 mineasy
Guide · TV

TV stuck on logo / restarting (boot loop)

Usually firmware or main board, occasionally power supply. Try a full power drain and a firmware recovery/factory reset before replacing boards.

4 steps ~60 minmoderate
Guide · TV

TV switches HDMI input by itself

HDMI-CEC 'one touch play' lets a device grab the input. Turning CEC off and clearing saved device history usually stops it.

3 steps ~15 mineasy
Guide · TV

TV turns on or off by itself (HDMI-CEC, mobile power-on)

Most phantom power events come from HDMI-CEC (Samsung Anynet+, LG SimpLink): a connected device sends a power command. Network 'power on' features and a damaged cord are the other causes.

5 steps ~20 mineasy
Guide · TV

TV won't connect over Ethernet (wired)

Work from the cable outward: cable and port lights, router port, then status screen and modem/ISP.

4 steps ~20 mineasy
Guide · TV

TV won't connect to Wi-Fi / network error codes

Find out whether the TV can't join the router or joins but has no internet. A phone hotspot test splits TV vs. home network fast.

6 steps ~20 mineasy
Guide · TV

TV won't turn on (standby light only, or blinking)

Separate power-delivery problems (outlet, surge strip, remote) from internal failures. A steady standby light with no response is often remote or button related; a blinking light after a clean power cycle on a good outlet is a hardware fault, usually the power supply board.

5 steps ~45 minmoderate
Guide · TV

Vertical or horizontal lines on screen (T-con vs panel)

Decide if the lines are in the source, the T-con/ribbons, or the panel. Lines that pass through the TV's own menu are internal; single fixed thin lines usually point to the panel's COF/ribbon, grouped or shifting lines more often to the T-con.

5 steps ~60 minadvanced
Guide · TV

Wall-mounted TV loose, sagging or unsafe

Check fastening into structure, mount rating versus TV weight, and the TV-side screws. Most failures are drywall-only anchoring or wrong VESA screws.

4 steps ~45 minmoderate
Guide · TV

Wrong colors or green / purple tint

The TV's built-in picture test splits the problem: if the test pattern is wrong, it is the TV (panel or board); if it looks fine, the cause is the source, cable or settings.

5 steps ~25 mineasy

Component tests · 3

Component test · TV

T-con (timing control) board: board or panel?

The T-con converts video from the main board into the signals that drive the panel rows and columns. Loose ribbons, a blown T-con fuse or a failed T-con cause image faults; lines that stay fixed in the same place usually mean the panel itself.

5 steps ~45 minadvanced
Component test · TV

TV LED backlight strips and LED driver

LED strips are wired in series strings and run from a constant-current driver at high DC voltage (often around 80-200 V total). One dead LED opens the string and the driver shuts down. Test LEDs with a backlight tester, not a meter diode range, and replace all strips as a set.

6 steps ~120 minadvanced
Component test · TV

TV power supply board

The power supply board makes a standby voltage that is always on, then switches on the main rails when the main board sends a power-on signal. Check standby, then the power-on signal, then main rails. The primary side holds a high-voltage charge.

5 steps ~45 minadvanced

Installation · 1

Install · TV

TV wall mounting: studs, VESA, cable routing and in-wall power

Choose a mount that matches the TV VESA pattern and weight, anchor it into studs (or masonry anchors on brick/concrete), and hide cables only with in-wall-rated cable or a recessed power kit. Running the TV power cord itself inside the wall is not an accepted practice under the electrical code: use a listed in-wall power kit or a new outlet installed by an electrician where required.

6 steps ~90 minmoderate

Epson · 6 codes

Epson · TV

Lamp + Temp lights solid orange

Power error

Single source High-voltage / caution

Epson · TV

Lamp light flashing orange

Lamp near end of life

Single source High-voltage / caution

Epson · TV

Lamp light solid orange

Lamp problem

Single source High-voltage / caution

Epson · TV

Temp light flashing orange

Projector running too hot

Single source

Epson · TV

Temp light flashing orange (power off)

Fan or sensor fault

Single source High-voltage / caution

Epson · TV

Temp light solid orange (power off)

Overheated and shut off

Single source

Hisense · 1 codes

Hisense · TV

Red light blinking (no picture)

Power/backlight fault (blink counts unreliable)

Single source High-voltage / caution

LG · 8 codes

LG · TV

-105 (in apps)

Network / DNS error in app

Single source

LG · TV

105

Network error (meaning disputed)

Single source

LG · TV

106

Network connection error

Cross-checked

LG · TV

Magic Remote power light flashing

Remote lost pairing or low battery

Single source

LG · TV

Network status: X at DNS

DNS failure

Single source

LG · TV

Network status: X at Internet

Router OK, no internet

Single source

LG · TV

Network status: X between TV and Gateway

TV not reaching the router

Single source

LG · TV

Red power LED blinking

Power-on failure

Single source High-voltage / caution

Panasonic · 2 codes

Panasonic · TV

Red LED blinks 13x

Board communication error (reported)

Single source High-voltage / caution

Panasonic · TV

Red LED blinks 14x

Protection shutdown (reported)

Single source High-voltage / caution

Roku · 3 codes

Roku · TV

020

HDCP error (reported)

Cross-checked

Roku · TV

022

Wireless receiver not detected

Cross-checked

Roku · TV

HDCP Error Detected / purple screen

HDMI copy-protection (HDCP) failure

Cross-checked

Roku TV · 17 codes

Roku TV · TV

001

Can't reach the update server

Cross-checked

Roku TV · TV

002

Connection too weak for update

Cross-checked

Roku TV · TV

003

Software update can't download

Cross-checked

Roku TV · TV

004 / 005

Update failed / timed out

Cross-checked

Roku TV · TV

009

Connected to router, no internet

Cross-checked

Roku TV · TV

011

Cannot connect to Roku (setup update failed)

Cross-checked

Roku TV · TV

012 / 013

Wired network error

Cross-checked

Roku TV · TV

014

Wi-Fi connection failed

Cross-checked

Roku TV · TV

014.10 / 014.11

Joined the router but no internet

Cross-checked

Roku TV · TV

014.20

Weak Wi-Fi signal

Cross-checked

Roku TV · TV

014.30

Wi-Fi connection failed (often weak signal)

Cross-checked

Roku TV · TV

014.40 / 014.41

Wrong Wi-Fi password or router blocking

Cross-checked

Roku TV · TV

014.50

Wireless connection failed (signal)

Cross-checked

Roku TV · TV

014.62 / 014.64

Weak signal / can't reach internet

Cross-checked

Roku TV · TV

016

Connection lost while launching

Cross-checked

Roku TV · TV

017

Poor wireless signal

Cross-checked

Roku TV · TV

018

Internet too slow

Cross-checked

Samsung · 9 codes

Samsung · TV

012

Network/app connection error

Single source

Samsung · TV

102

Cannot reach Smart Hub server

Cross-checked

Samsung · TV

107

No internet for Smart Hub

Cross-checked

Samsung · TV

116

Unable to connect to server (reported)

Single source

Samsung · TV

189

App download failed (reported)

Single source

Samsung · TV

301

Smart Hub error (reported)

Single source

Samsung · TV

Smart Remote LED blinks twice

Bluetooth link to TV dropped

Single source

Samsung · TV

Standby light blinking

Power fault / hardware fault

Cross-checked High-voltage / caution

Samsung · TV

Subwoofer blue LED keeps blinking

Subwoofer pairing failed

Single source

Sony · 7 codes

Sony · TV

Red LED blinks 2x

Power supply protection

Cross-checked High-voltage / caution

Sony · TV

Red LED blinks 3x

Main board / board communication fault

Single source High-voltage / caution

Sony · TV

Red LED blinks 4x

Backlight driver / power or main board

Single source High-voltage / caution

Sony · TV

Red LED blinks 5x

T-con / panel fault

Cross-checked High-voltage / caution

Sony · TV

Red LED blinks 6x

Backlight fault

Cross-checked High-voltage / caution

Sony · TV

Red LED blinks 7x

Over-temperature

Single source

Sony · TV

Red LED blinks 8x

Audio circuit fault

Single source High-voltage / caution

Vizio · 2 codes

Vizio · TV

2902_1

SmartCast cannot reach the internet

Single source

Vizio · TV

Power light blinking / fading (white or orange)

Failed power-on self-test

Single source High-voltage / caution

Official manufacturer support

We link to official documentation and never host it.

RokuRoku support: Wi-Fi & connectivity articlesAmazon Fire TVAmazon Fire TV help (black/blank screen)EpsonEpson projector support & FAQsSamsungSamsung US soundbar: connect the subwooferSamsungSamsung US TV supportLGLG US supportTCLTCL support (Roku TV & Google TV models)VizioVizio supportSonySony electronics supportHisenseHisense USA supportRoku TVRoku support