DJ is just a profession, not a musical style. DJ's skill is called disc playing, which can also be said to be the technical term for disc playing. The following is a guide to the safe use of DJ equipment for everyone, hoping to be your reference ~

1. Pay attention to the operating conditions of the machine:

Usually, the operating conditions of the machine will be listed in the operating instructions of the machine, such as:

1. Ambient temperature:-10℃-+40℃

2. Relative humidity: 50%-80%

3. Power supply voltage: 198V-242V.

4. Power frequency: 50Hz—60Hz

Specifically, it needs:

1. Avoid using the machine in an environment with extremely low or high temperature, and avoid direct sunlight on the machine surface.

2. Avoid using the machine in a humid environment to avoid premature damage of machine parts or premature rust of the machine.

3. Before use, it must be confirmed that the local power supply voltage is consistent with this machine.

2. Pay attention to the use environment of the machine:

1. Avoid using the machine in dust and vibration environment.

2. There should be enough space around the machine to facilitate the heat dissipation of the machine.

3. For the power amplifier, special attention should be paid to keep the cooling channel unblocked.

3. Matters needing attention in the use of the machine:

1. In the sound system, pay attention to the sequence of startup and shutdown. Turn on the front equipment such as audio source before turning on the power amplifier; When shutting down, the power amplifier should be turned off first, and then the front equipment such as audio source should be turned off. If the audio equipment has a volume knob, it is best to turn it off to the minimum before switching it on. The purpose of this is to reduce the influence on the speaker when it is turned on and off.

2. It is forbidden to plug the signal plug with electricity. In order to avoid impact and damage to the machine or speakers.

3. If the machine makes abnormal sounds during operation, turn off the power immediately and stop using it. And please experienced qualified maintenance personnel for maintenance. Don't open the machine without authorization, so as not to cause greater damage to the machine or cause electric shock accidents.

4. Pay attention to the maintenance of the machine:

1. Don't use volatile solution to clean the machine, such as wiping the machine surface with gasoline and alcohol, and removing dust with a soft cloth. And unplug the power supply before cleaning the casing.

General machines are not waterproof. If it is wet, dry the water stain with a dry cloth. Only when the water is completely dry can you start working.

3. Don't put heavy objects on the machine, lest the machine be deformed.

Verb (abbreviation for verb) Safe use of machines:

1. Don't plug the power supply with wet hands to avoid electric shock.

2. When not used for a long time, please unplug the power plug from the power socket.

3. Don't let iron needles, hairpins, coins and other metal conductive substances fall into the machine to avoid damaging the machine.

4. When replacing the machine fuse, it should be replaced in strict accordance with the requirements, and unqualified substitutes are strictly prohibited.

5. When the machine is in use, the chassis grounding point should be safely grounded.

6. It is forbidden for the machine to work under overload or short circuit.

7. In a constant voltage power amplifier, the output terminal will have a high output voltage, and the output terminal lead is generally long, so it is necessary to ensure the safety and reliability of the output terminal lead in use.

6. Pay attention to the protection of the power cord:

1. Pay attention to avoid the power cord being crushed by heavy objects.

2. Don't pull, plug or twist the power cord.

3. When pulling out the plug from the socket, grab the plug and pull it out.

In a word, modern audio equipment belongs to high-tech products, which must be carefully maintained, used safely and operated correctly. In order to enjoy the beauty and avoid unexpected losses.

Noise and grounding problems

Earth and electricity (signal), these are inseparable twins. Grounding usually refers to connecting with the earth with a conductor. But in electronic technology, the ground may have nothing to do with it, it is only the first level potential surface in the circuit. Such as the ground in radio and television, it is only a potential reference point in the receiver circuit. In power and electronic technology, grounding is simple and complex, and it is very important. According to the function of grounding, it can be divided into working grounding, protective grounding, overvoltage protection grounding, anti-static grounding, shielding grounding and signal grounding. In radio and television technology, the above grounding types will be encountered. This paper expounds some grounding technical problems in combination with practice.

I. Protective grounding

Protective grounding is a protective device to prevent equipment from being charged and endangering personal safety due to insulation damage. It has two ways: grounding and zero connection. According to the electric power regulations, the neutral wire of the three-phase four-wire power supply system should be grounded, so the metal shell of the equipment should be connected to the neutral wire through the conductor, and it is not allowed to directly ground the equipment shell. This is especially common in the switching equipment in the distribution room of radio and television system, power switching equipment such as central air conditioner and transmitter, and large power consumption equipment. When planning and designing, the grounding bus should be led out from the grounding grid to each device, and then the chassis should be connected to the grounding bus with wires. It is worth pointing out that the grounding wire should be connected to the special grounding terminal of the equipment, and the other end should be welded.

Sometimes the equipment shell will be numb, which is caused by AC leakage and the equipment shell is not connected to zero. Generally, it can be solved by pulling out the power plug and plugging it in another position. In some frequently moving cataloging equipment, because the zero line is often ignored, some operators may encounter equipment with and without zero line at the same time, which happens from time to time.

2. Overvoltage protection grounding

This is a lightning protection and grounding device. Lightning rod and lightning arrester are the most widely used lightning protection devices. Lightning rods enter the ground through the steel bars of towers or buildings, and lightning arresters enter the ground through special grounding wires. Lightning arresters must be inspected before the thunderstorm season every year to prevent failure. If the hotline access equipment of our station is struck by lightning, it is caused by the failure of the lightning protection device of the telephone line. Do not connect the grounding wire of other equipment on the lightning protection downlead. Lightning protection downlead can only be directly grounded separately, otherwise lightning will damage other equipment through downlead. For example, a satellite TV receiver was struck by lightning many times. The original fault was that the feeder rubbed against the roof metal guardrail and the insulation was damaged, while the metal guardrail was welded with the lower part of the lightning rod, which caused lightning to rush in and damaged the receiver.

Three. Shielding land

In order to prevent electromagnetic induction, it is a protective measure to ground the shielding metal sheath of audio and video wires, the metal shell of electronic equipment, the shielding cover and the metal shielding net of buildings (such as the shielding room for measuring sensitivity and selectivity). Among all grounding, shielding grounding is the most complicated, and there is a feeling of unclear and unclear. Because shielding itself can not only prevent external interference, but also interfere with the outside world through it, and electromagnetic interference must also be prevented between components in the equipment, such as the well-known middle shell and electron tube shield.

Poor shielding and improper grounding will cause interference, mainly including:

1. AC interference, mainly caused by AC power supply. The measures to prevent AC interference are usually to filter the power supply or to add a shielding layer between the primary of the power transformer and the ground. In addition to the large stray electromagnetic field, it is also necessary to shield grounding to prevent electromagnetic interference. For example, at the groundbreaking ceremony of Xinya New Mall in our city, there was a transformer near the recording and playback equipment, and its electromagnetic field interfered with the recording and playback on the spot. After that, the problem was solved by shielding the recording and expanding equipment and grounding it.

2. High frequency interference. This kind of interference comes from the frequency conversion or overclocking signals of various wireless transmitters, which are abnormally demodulated in the machine after breaking into electronic equipment, forming audio interference.

The higher the signal frequency, the smaller the metal mesh hole of the building or equipment, and the denser the shielding layer of the signal line, otherwise the shielding effect will be lost. For signal wires that are often unplugged, the shielding layer should be prevented from loosening and falling off at the plug. Because sometimes the shielding of instruments and equipment is grounded through the shielding of signal lines (they are connected through plugs and sockets), if the shielding falls off, it is easy to cause interference. For example, when I was in an electronics factory in Shantou, testers reported that satellite TV receivers sometimes had noise interference, which affected the image quality. After tracking and observation, it is related to the passage of aircraft, which is obviously caused by the radar signal invasion and abnormal demodulation of Chenghai Airport. After analysis and search, it turned out that the shielding layer of the signal line outside the plug fell off, which led to the grounding of the satellite TV receiver.

Four. Signal grounding

All kinds of electronic circuits have a reference potential point, which is the signal ground. Its function is to ensure that the circuit has a unified reference potential and will not float and cause signal error.

The connection of signal ground is: the signal input ground and signal output ground of the same equipment cannot be connected together, but should be separated; The output ground of the previous stage (equipment) is only connected with the input ground of the latter stage (equipment). Otherwise, the signal may form feedback through the ground wire, causing the signal to float. When testing equipment, special attention should be paid to the connection of signal ground. For example, when I was working in an electronics company, the quality inspection department reported that the quality inspection results of satellite receivers were different. Originally, some shells of the testing instruments in the quality inspection department were grounded, and some shells were not grounded (the testing signals were transmitted from the signal center to various departments), so that the signals were fed back through the ground and the measurement results were inconsistent. After all grounded test instruments are set to ungrounded, this phenomenon is gone.

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