Repair guides
Pick a type, an appliance or a brand. Every guide lists the tools, the safety call-outs, the steps and the reading you should expect.
Diagnostic · 374
Symptom → most likely cause, step by step
Component tests · 69
How to test a specific part, with expected readings
Installation · 33
Install, replace and hook up appliances correctly
Fundamentals · 24
Core skills every appliance tech uses
Appliance
Brand-specific guides
31 guides · TVs
Diagnostic · 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.
Guide · TVApps 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.
Guide · TVAudio 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.
Guide · TVBluetooth / 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.
Guide · TVFactory 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.
Guide · TVFirmware 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.
Guide · TVFlicker 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.
Guide · TVHalf 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.
Guide · TVHDCP 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.
Guide · TVLED 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.
Guide · TVNo 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.
Guide · TVOLED 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.
Guide · TVPicture 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.
Guide · TVPicture 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.
Guide · TVRoku 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.
Guide · TVSound 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.
Guide · TVSoundbar 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.
Guide · TVTV 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.
Guide · TVTV 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.
Guide · TVTV 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.
Guide · TVTV 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.
Guide · TVTV won't connect over Ethernet (wired)
Work from the cable outward: cable and port lights, router port, then status screen and modem/ISP.
Guide · TVTV 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.
Guide · TVTV 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.
Guide · TVVertical 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.
Guide · TVWall-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.
Guide · TVWrong 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.
Component tests · 3
Component test · TVT-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.
Component test · TVTV 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.
Component test · TVTV 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.