# Working TV – Remote & Internals

How a flat TV wakes from standby, reads infrared remote codes, and turns power and LED backlight into the coloured pixels on screen\.

By BobMorane

Topic: Machines

[Open the interactive Jig](https://ask.jig.com/j/bJcc4gXgnQkR)

## Transcript

### 1. A TV that is only sleeping

This flat TV looks off, but the little red light under the screen says it is only in standby\. A small part inside stays awake, listening for the remote\. Press the red key on the remote, or the button below, to wake it\.

Tap any key on the remote to use it\. Drag anywhere else to turn the view\.

### 2. A message made of light

Each key makes a tiny lamp at the tip of the remote blink in a short code\. The light is infrared, a colour our eyes cannot see, so the code is drawn here as a striped beam\. Try the number keys and the channel keys\.

The lamp flickers about 38,000 times a second, and a whole code takes less than a tenth of a second\.

### 3. The TV's eye

Behind a dark window under the screen sits a light sensor tuned to that flicker\. It turns the flashes back into a code, such as channel up, and hands it to the TV's brain\. Its window glows here whenever a code arrives\.

A phone camera can see a remote's infrared flash as a purple glow\.

### 4. Open the back

Lift off the plastic back cover\. Inside, a few flat boards sit on a steel plate\. The yellow one is the power board, the big green one is the main board, the TV's brain, and the small green one in the middle sets the timing\. Two speakers lie along the bottom\.

Real TVs hold mains voltage inside, so only repair experts open them\.

### 5. Electricity flows in

Yellow stripes show electricity\. It comes from the wall socket, called the mains, at 100 to 240 volts\. The power board turns it into gentle low voltages for each board and the lights\. Switch the TV off: only a trickle keeps the brain listening\.

Pink stripes carry the picture to the timing board\. The metal fins on the power board, a heat sink, carry away heat and warm up as the TV runs\.

### 6. Light from behind

The picture starts as plain white light from rows of tiny LEDs behind the screen\. A milky diffuser sheet spreads that light evenly\. In front, a layer of liquid crystals, a material that twists when it gets a voltage, works like millions of tiny shutters\.

LEDs are light\-emitting diodes\. In this kind of TV they never make the colours themselves\.

### 7. Red, green and blue

Look very closely and each dot of the picture, a pixel, is three tiny windows: red, green and blue\. Mixing their brightness makes every colour you see\. A 4K TV has about 8\.3 million pixels and redraws them about 60 times every second\.

From the sofa the windows are far too small to see, so the colours blend together\.

### 8. Pick a channel

Now you know the whole journey\. A flash from the remote carries a code to the brain, the power board feeds every part, the LEDs make light and the pixels add colour\. Choose a channel here, or use the remote\. The volume keys make the speakers shake harder\.