About the repair of UMZCH on ICs. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Transistor power amplifiers

 Comments on the article

A few years ago, when repairing amplifiers of imported portable equipment, it was most often possible to use K174UN14 microcircuits connected according to a typical switching circuit [1]. In general, a similar situation persists to this day, since in small towns the range of imported ICs is small. In addition, most of the replaced imported UMZCH ICs do not have OS circuits similar to the typical K174UN14 inclusion. Their inverting inputs, as a rule, are connected to a common wire through capacitors with a capacity of 100 ... 200 microfarads.

It must be said that the K174UN14 chip in such an inclusion (Fig. 1) works quite well, and therefore there is no need to look for low-resistance resistors for the OS, but an RC circuit. shunting acoustic system, as a rule, is available.

Similar simplifications are also possible in the bridge connection of this IC (Fig. 2). Moreover, it was used, and quite successfully, in the domestic-made car player "Electronics P-303SA".

Of course, the parameters of the UMZCH given here are not high, but when repairing portable equipment manufactured in Southeast Asia, in which the preamplifier is made on two transistors in each channel (recently, devices with a two-channel head, stereo UMZCH, balance control and monophonic preamplifier), without altering the preamplifier, it makes no sense to use a high-quality final amplifier.

In high-quality equipment, it is still more convenient to use imported bridge ICs, for example. KIA6205, KIA6210, TA8205, TA8210, TDA7370. Any of them replaces four K174UN14 microcircuits and has simpler switching circuits [2].

Earlier in the magazine it was noted that almost all cheap (without auto-reverse mode) imported car radios that use TDA2003, an analogue of K174UN14, as UMZCH, are excited at a low frequency even at partial power due to a low-quality preamplifier. One of the simplest ways to eliminate this defect is to raise the HF and “blockage” the LF by replacing the 2,2 Ohm resistor in the CFO circuit with a 10 ... 27 Ohm resistor and a 100 ... 200 μF capacitor connected in parallel.

In repaired models, there are resistors with a resistance of 1 to 4,7 ohms. Finding such a resistor on the board is quite easy. It has two golden stripes and is usually located on the edge of the circuit board. When reworking, a capacitor is installed in its place, with a minus to the common wire, and a 10 ... 27 Ohm resistor is soldered to the board from the side of the printed conductors.

And the last. In various home-made designs of recent years, even if an output power of more than 0.5 W is not required, the same K174UN14 is used as an UMZCH, although small-sized imported ICs with simple correction circuits are now becoming more accessible. For example, KA2209 is a stereo UMZCH in a DIP-8 package. Its nominal output power is 2x0,65 W, the price according to the catalog of the company PLATAN, which sells radio components, is 2500 rubles. The scheme for switching on this microcircuit in the Chinese two-cassette radio tape recorder "INTERNATIONAL" is shown in fig. 3. In such models, an oxide capacitor C3 is sometimes used with a smaller capacitance - 220 uF.

Another chip is a single-channel UMZCH LM386-1 with a rated output power of 0,325 watts. also in DIP-8 package. Its cost in the same PLANET is 1700 rubles. As an example, in fig. 4 shows a diagram of its inclusion in the Chinese car reverse signaling device.

And, finally, more expensive, but very easy to connect, is the UMZCH TDA7052 chip (Fig. 5), it is also on sale.

Literature

1. Yakovlev G. The use of K174 series microcircuits in AF amplifiers. - Radio. 1994. No. 12. p. 12.
2. E. Turuta, L. Dancl. Integrated circuits - low-frequency power amplifiers. - Edilura Virginia", Chlslnau. 1994.

Author: A.Prozorov, Aldan, Yakutia

See other articles Section Transistor power amplifiers.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Machine for thinning flowers in gardens 02.05.2024

In modern agriculture, technological progress is developing aimed at increasing the efficiency of plant care processes. The innovative Florix flower thinning machine was presented in Italy, designed to optimize the harvesting stage. This tool is equipped with mobile arms, allowing it to be easily adapted to the needs of the garden. The operator can adjust the speed of the thin wires by controlling them from the tractor cab using a joystick. This approach significantly increases the efficiency of the flower thinning process, providing the possibility of individual adjustment to the specific conditions of the garden, as well as the variety and type of fruit grown in it. After testing the Florix machine for two years on various types of fruit, the results were very encouraging. Farmers such as Filiberto Montanari, who has used a Florix machine for several years, have reported a significant reduction in the time and labor required to thin flowers. ... >>

Advanced Infrared Microscope 02.05.2024

Microscopes play an important role in scientific research, allowing scientists to delve into structures and processes invisible to the eye. However, various microscopy methods have their limitations, and among them was the limitation of resolution when using the infrared range. But the latest achievements of Japanese researchers from the University of Tokyo open up new prospects for studying the microworld. Scientists from the University of Tokyo have unveiled a new microscope that will revolutionize the capabilities of infrared microscopy. This advanced instrument allows you to see the internal structures of living bacteria with amazing clarity on the nanometer scale. Typically, mid-infrared microscopes are limited by low resolution, but the latest development from Japanese researchers overcomes these limitations. According to scientists, the developed microscope allows creating images with a resolution of up to 120 nanometers, which is 30 times higher than the resolution of traditional microscopes. ... >>

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

Random news from the Archive Chimpanzee Inventors 07.02.2010 Chimpanzees, in order to get tasty termites from the termite mound, stick a stick into the termite mound. Insects feeding on wood cling to a stick, after which the monkey licks its fishing gear. Chimpanzees from the Nuabale-Ndoki National Park in the Congo have perfected this method. They found a species of trees that have a sticky sap under the bark, they remove the bark from a branch of this tree with their teeth and stick it into the termite mound. Termites stick, and catches immediately grow.

Other interesting news:

▪ The sense of smell will help diagnose the state of the brain

▪ Intel Core Duo 2

▪ masked camera

▪ Luminous target of the surgeon

▪ Cinema for smokers

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Data transfer. Article selection

▪ article Who is in the forest, who is for firewood. Popular expression

▪ article A real python was once lost in the office of which company on April 1st? Detailed answer

▪ article Cultural peanuts. Legends, cultivation, methods of application

▪ article Frequency dividers with a fractional division factor. Encyclopedia of radio electronics and electrical engineering

▪ article Regenerative KB receiver. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua
2000-2024