Repair the bedroom light under the double control switch with an electric pen etc.
The light in the bedroom suddenly went off and decided to fix it. The lights are controlled by a double-control switch. The lights originally have different brightness levels. There are three headlights on, N crystal lights on, and all the lights are on. It is estimated that the electrical components in the lamp are aging, and it is planned to change to only the headlights, and those dazzling functions of the small lights are useless to us.
The multi-function test pen (digital display type) is divided into 12V, 36V, 55V, 110V, 220V, can measure alternating current and direct current (12-250V), and has the function of testing induction electricity (hand contact is "Induction" in the picture above xxxx Test”), the highest voltage range is displayed as the approximate voltage value measured at that time. The inductive breakpoint test is used to test where the cable is broken. It is said that it cannot be immersed in water, and it will be reported to be destroyed if it is immersed in water (indicating that it does not understand, who can test it).
If it is displayed as 12V36V55V110V220, it means the voltage is 220 volts; if it is displayed as 12V36V55V110, it means the voltage is 110 volts; if it is displayed as 12V36V55, it means the voltage is 55 volts; if it is displayed as 12V36, it means the voltage is 36 volts; if it is displayed as 12, it means the voltage is 12 volts.
When measuring alternating current, press your finger on the contact that is directly tested (“Direct Test”); when measuring direct current, press and hold “Direct Test”, press the positive electrode of the battery with the other hand, and press the negative electrode with the pen tip.
The working principle of both kinds of electric pens is the same: Ohm's law I=U/R and the total resistance relationship of the series circuit: R=R1 (people) + R2 (electric pen). The resistance of the human body is generally very small, usually only a few hundred to several thousand ohms, while the resistance inside the test pen is usually about several megohms. The current through the test pen (that is, the current through the human body) is very small, usually less than 1 mA , When such a small current passes through the human body, it does not harm people, but it can make the electric pen display (or the neon light is on, or the digital display).
The voltage of the live wire should be 220V. When the switch is open, the neutral line should have no voltage; when the switch is closed, the neutral line may display a voltage of 55 volts or less (connected with an electrical appliance), or 110V (this is the electronics on the lamp in my house). Component failure shows 110V, it may also be that the neutral wire of the live wire is reversed, in short, pay attention).
With an electric pen, first determine whether there is a problem with the dual-control switch, and finally check whether there is a problem with the lights on the roof (the lights in the center of the roof are really difficult to operate). Soon, it was checked that there was no problem with the wiring of the dual control switch, and there was no problem with the on and off. Dual control means that 2 sets of switches can control 1 light without affecting each other (that is, a switch at the door of the bedroom, a switch at the bedside, and control the lights on the top of the bedroom at the same time)
I had to disassemble the roof light. There are mainly 3 electronic components in the light. According to the instructions on the shell, I only know the approximate function (segment control (equivalent to outputting 3 states), converted into DC 3V, AC 12V, etc.), since I only need to use 3 energy-saving lamps with 220V input, I remove these 3 electronic devices and continue to use the wires inside. The wire inside the lamp socket and the wire on the wall are fastened by screwing, so I stood on the stairs alone, and it took a lot of effort to fix it.
