Electronic component

Detection method:

In electronic circuits, in addition to the most exposed electronic components (such as resistors, capacitors, inductors, diodes, audiodes, integrated circuits, etc.), there are other commonly used electronic components, such as electroacoustic devices, connectors and switches. [2]

1 General detection and selection of electroacoustic devices

Electroacoustic device refers to the device that can convert electrosound into audio electrical signal or audio electrical signal into sound energy. Common electroacoustic devices include loudspeakers, microphones, earphones and so on.

1.1 Loudspeakers

General detection of high, medium and woofer intuitive discrimination: because the effective frequency range of the test speaker is more troublesome, it is more intuitive to judge according to its diameter size and the softness of the paper basin to roughly determine its frequency response. In general, the larger the diameter of the speaker, the softer the edge of the basin, the better the low frequency characteristics, on the contrary, the smaller the diameter of the speaker, the harder and lighter the basin, the better the treble characteristics.

Check the sound quality: Measure the impedance of the speaker with the R × 1Ω stop of the multimeter. As soon as the pen touches the pin, you can hear the click sound, the louder the click sound speaker, the higher the efficiency of the electro-acoustic conversion, the clearer and cleaner the click sound speaker, the better the sound quality. If the multimeter pointer does not swing when touched, it indicates that the voice coil or voice coil lead cable of the speaker is disconnected. If only the pointer swings, but there is no click sound, it indicates that the speaker's voice coil lead line has a short circuit.

1.2 Microphone

General detection: The moving coil microphone can be used to simply judge its quality with a multimeter (capacitive microphone should not be measured with a multimeter). When measuring, the multimeter is placed in R × 10Ω or R × 100Ω, the two meter hands are connected with the plug of the microphone, at this time, the multimeter should have a certain DC resistance indication, the high impedance microphone is about 1 ~ 2kΩ, and the low impedance microphone is about tens of euros. If the resistance is zero or infinite, it means that there may be a short circuit or open circuit inside the microphone.

1.3 Earphones

General detection: Commonly used headphones are divided into high impedance and low impedance two. High-impedance earphones are generally 800 ~ 2000 Ω, and low-impedance earphones are generally about 8 Ω. If you find that the headset is silent, but the sound source is good, you can use a multimeter to measure.

When checking low-impedance earphones, use a multimeter R x 1Ω. For the method, refer to the method of using a multimeter to determine whether the loudspeaker is good or bad.

When measuring with a high-impedance headphone multimeter, dial the multimeter to R × 100Ω. Generally, the pointer points to about 800Ω. If the pointer points to R = 0 or the pointer does not deflect, it indicates that there is a fault, and the terminal in the headphone may be short-circuited or disconnected. After unscrewing the earphone plug, if the wiring on the terminal is found to be correct, it indicates that the earphone coil is faulty.

Stereo headphones are generally three-core plugs, and one of the two cores is an R channel and one is an L channel. Simply put, it is equal to two earphones, so it is OK to check separately when checking.

2 General inspection and selection of connectors and switches

The general point of the detection of connectors and switches is that the contact is reliable and the conversion is accurate, and the requirements can be met by visual inspection and multimeter measurement.

(1) Visual inspection

The non-sealed switch and connector can be inspected first. The main work in the inspection is to check whether the whole is complete, whether there is damage, whether the contact part is damaged, deformed, loose, oxidized or lost elasticity. The band switch should also check whether the positioning is accurate, whether there is dislocation, short circuit and so on.

(2) Use a multimeter to measure

Place the multimeter in stop R × 1Ω and measure the DC resistance between the two contacts. The resistance should be zero. Otherwise, the contacts are not in good contact. Place the multimeter in R × 1 kΩ or R × 10 kΩ, and measure the resistance between the contacts and the contact to the "ground" after the contact is disconnected. This value should be infinity, otherwise it indicates that the insulation performance of the switch and connector is not good.