Installation and repair of a backlit switch

Switches play an important role in rooms - they actually provide the appearance of artificial light. At the same time, there are devices in which the backlight in the dark is off. This is very convenient when you enter a dark room with no windows and immediately see a place where you can turn on the light. But how to handle such switches and how to repair them? We will talk about this in this article.

Illuminated switch device

First, let's figure out what the filling of such a device is. In fact, it is not much different from the insides of a conventional switch without backlight. Just in addition to the NC contacts controlled by the keys, there is also an additional electrical line.

This is an additional backlight circuit, which consists of a current-limiting resistor and a neon bulb or LED. When the switch is in the open position of the power supply contact to the indoor lamp, current flows through the backlight line, using the spiral of the lighting lamp as the closing element of the circuit.

If the switch contact is open, current flows through the backlight circuit and turns on the LED

In this case, the resistor located in the backlight circuit limits the current passing through it, so there is not enough voltage to light the room lamp. And the LED lights up - it needs much less current. When the switch is activated, the voltage begins to act exclusively on the main lamp, and the backlight goes out.

When the switch contact closes, current begins to flow along the lamp power circuit (along the path of least resistance) and turns it on, the backlight goes out

Based on the described principle of current passage, it becomes clear that such a device will work correctly only when connected to a phase wire (which is always energized). But we will talk more about the wisdom of wiring a circuit breaker with an additional circuit further.

How to connect the device with backlight: step by step instructions

So, the main axiom, characteristic, in fact, for mounting any switch, is as follows: to light disconnection device let only the phase wire. This is indicated in the Electrical Installation Rules (PUE). Otherwise, if you bring the supply line to the chandelier, and the neutral wire to the switch, a person changing the lamps in the lighting device may be shocked.

The process of connecting the described node with backlight also differs little from the installation algorithm of a conventional switch. We give it in the form of instructions.

Here it is assumed that a universal cup is already installed in the socket for the device and wires are connected.

The wiring diagram and connecting them to the switch terminals does not depend on the presence of a backlight in it

And here is the instruction itself.

1. First, they turn off the power supply in the apartment panel - this is strictly necessary.
2. Then remove the keys from the installed device. To do this, they are gently poked on the side with a screwdriver with a thin sting.
   

   Each key (if there are several of them on the device) is gently pried by a screwdriver, wound into a slot, and separated from the case

3. Hands pull out the front plastic panel for facing.
   

   After removing the cladding panel, access to the main mechanism of the switch appears

4. After these manipulations, we have before us the mechanism of the device, which has a toothed metal antennae on the back for mounting in a socket.
5. The bare end of the supply wire is inserted into one of the contacts and the screw is tightened. The same thing is done with the exit link - they fix in it the line coming from the room lamp. The order of connecting the wires in this case does not matter.
   

   Two wires should come to the switch - from the junction box and from the lamp, they must be connected to the contacts on the case

6. Next, insert the filling of the device into a glass inside the wall and tighten with a screwdriver the screws that press on the antennae. The latter and fix the switch in the glass.
   

   The metal case is carefully inserted into the socket and attached to it with two screws

7. At the final stage, install the front panel and keys back.
8. Turning on the machine in the shield, check the operation of the switch. When the circuit is open, the backlight should be on.

When there are a lot of feeding machines in the apartment, and the desired one is unknown, they proceed as follows. Agree with the assistant, he turns off the "circuit breakers" in turn. The owner substitutes a tester screwdriver with a sting for the exposed supply wire in a glass. At the same time, he puts his finger to the end of the probe handle. The LED in the screwdriver will turn off when the assistant turns off the desired machine.

If, after completion of work, it turned out that the backlight of the device is not lit, it is necessary to dismantle the switch, acting in the reverse order, and check its serviceability with a multimeter. But let's talk about diagnostics and repair of the device with backlight in a special section of the article.

As for switches with several keys and a backlight, all of the above is also characteristic of them. Regardless of the number of keys, the backlight circuit always has the device already described.

There are also devices with remote control. They have a so-called reception point, which is mounted in the room. The main control circuit can be located in the shield. The receiver is reminiscent of a conventional switch. It may also have a backlight. Its installation is carried out by a professional electrician in accordance with the instructions attached to the product.

Related video: how to change a backlit switch

Can I turn off the backlight and how to do it

Suppose that we do not need LED operation at all. For example, we have a room in which there is always some kind of additional lighting. In this case, it is easy to turn a backlit instrument into a regular one.

To do this, we completely disassemble the removed switch according to the previously described scenario (that is, remove the keys and remove the lining). Then just remove the small backlight.

1. If its feeding antennae are inserted into the corresponding holes, then this node can only be pulled out with your fingers on yourself.
2. If the antennae are soldered into the device, you need to arm yourself with a small soldering iron and plug it into the network. After two to three minutes, the instrument will heat up. Now you need to gently, holding the soldering iron exclusively by the handle, touch the soldering tip with a sting. After a while, you can pull the light bulb towards yourself.

In order to disconnect the light bulb, it is enough to alternately touch the soldering places with the heated tip of the soldering iron and pull it towards you

If the backlight is broken or does not work properly

If after installation or during operation, the light inside the switch ceases to light, it is necessary to carry out diagnostics and repair.

For this:

1. We dismantle the switch by removing the keys, facing and unscrewing the mustache screws.
2. We pull the ends of the wires out of the contacts, loosening the bolts. The mechanism is before us.
   

   After disconnecting the switch from the wires, you can access the resistance and the LED that make up the backlight circuit

3. Take a device called a multimeter.
   

   A multimeter is used to measure current, voltage and resistance of circuit elements

4. We switch it to the position corresponding to the measurement of resistance with a scale of up to 200 kOhm (the arrow on the central switch should indicate the “200K” icon on the device body). When the probes of the device come into contact with each other, sound should appear. It means that the electric circuit of the multimeter has no breaks.
5. We substitute one probe of the device to the first output of the LED, and the other to the second. If the signal does not sound, then the node has burned out.
6. According to the scenario described earlier, we remove the LED or solder it with a soldering iron.
7. We buy the same in the radio parts store.
   

   LED for illumination can be purchased at any radio components store

8. If the LED was simply inserted into the socket, then install a new one with a flick of the wrist. Otherwise, solder it, acting in the reverse order of evaporation. You may need some solder here.

The question may arise: how to check the resistor? But this does not need to be done. Firstly, because this process is much more complicated, and secondly, this part breaks very rarely.

After replacing the LED, it is necessary to mount the described device back to its regular place.

Video: backlit double-key switch repair

Backlit devices are quite reliable in operation. They are in no way inferior to conventional switches that do not have additional functions. Installing devices with backlight does not cause difficulties. The only negative - the cost of such a switch is slightly higher than that of a conventional one. But in the end, the installation site plays a decisive role, so the choice is up to the consumer.