Generally, a whole machine is composed of several printed circuit boards, which can be large or small. The circuit contained in each PCB is often drawn on a circuit diagram. Therefore, a circuit diagram of a whole machine is usually composed of several circuit diagrams. After reading each circuit diagram, the circuit diagram of the whole machine can be understood. Each circuit diagram of a whole machine contains one or more circuit systems. The complexity of the circuit diagram of a large plate is almost the same as that of a general small and medium-sized screen TV set. Although the circuit is relatively complex and various board circuits perform different functions, they have rules to follow and can be read step by step in accordance with certain methods.

　　In order to avoid detours in reading circuit diagrams, correct reading methods and processes should be used. Generally, the method of outsourcing from outside to inside is adopted. It can read all the circuit diagrams smoothly by adopting the methods of combining the table with the inside, contacting the front and back, and breaking step by step. Looking at the specific methods and processes of the map, we can summarize three sentences and three processes: starting from the periphery, choosing the import; opening the gap, contacting before and after; and analyzing the difficulties, putting them in the final place.

　　1. Start with intuition and select imports

　　That is to say, first look at the most intuitive and easy-to-read components and circuits at the edge of the circuit, as the import of reading pictures. A batch of circuits or integrated blocks can be found from these peripheral readily recognizable components inward along the signal line (possibly in the opposite direction of the signal flow).

　　2. Open the gap and contact back and forth

　　There are some weak links in any circuit diagram. The complexity and difficulty of each part of the circuit are always somewhat different, or the graphics and symbols of some components are different from those of ordinary components. These local weak links are the readable links, which can be used as the internal breakthrough of the graph. These local areas can be selected as the breakthrough for map reading. After opening the gap, it can contact forward, backward, left and right swiftly, cooperate with the first step method, and can read many circuits.

　　As long as the reader is careful, there will always be many links that the reader already knows in the circuit diagram. If we catch it, we can quickly open the gap of the diagram and develop in depth. The most intuitive and easy-to-read internal links are integrated circuits, especially those large scale integrated circuits, whose lead-out feet are more than 40, most of which reach more than 100. They are very eye-catching in the drawings. Drafters often place them in the center or obvious position of the circuit drawings. Then, with these integrated circuits as the center, many circuits can be found. It is necessary to know the specific models of these integrated circuits, the main functions of these integrated circuits, and the names and uses of their main lead-in pins. Otherwise, it will bring a lot of inconvenience to reading pictures. Sometimes the reader already knows most of the integrated circuits and some of their individual integrated circuits, and can guess the function of the unknown integrated circuit according to the block diagram and the connection between the front and back.

　　In the circuit diagram, there are some easy-to-read and easy-to-recall contents, which can also be used as the breakthrough in the circuit. For example, the Chinese characters, foreign letters or abbreviations marked in the figure, some important and readable graphic symbols of components, some adjustable resistors or potentiometers, etc. In order to use these breakthroughs conveniently and smoothly, the reader should understand the physical meanings of various foreign letters and abbreviations, and have a certain foreign language foundation (generally English). The reader should understand some professional terms and abbreviations commonly used by audio-visual equipment. The reader should understand the functions and parameters of these components. And indicators. Readers have a wider range of knowledge, which is conducive to reading pictures. Readers should consciously recall some useful knowledge.

　　3. Difficulty analysis, put in the final

　　After the above two steps of reading process, most of the content of the circuit diagram can be understood. However, the remaining local circuits do not understand or do not understand. The third step can be devoted to encircling and annihilating difficult points. This is the difficult part of looking at the picture, and also the final step of looking at the picture. Readers can break difficult circuits by various means or means.

　　On available circuit diagrams, difficult to understand localities are often manifested in two localities: one is the signal flow processing process within some integrated circuits, because these contents are not understood, the function of the external lead-in foot cannot be understood; the other is the circuit of some peripheral discrete components, which does not understand the purpose and significance of setting up the circuit. I don't know the signal processing process. With regard to these difficult circuits, according to the block diagram of the whole machine, according to the functions of each part of the circuit and their contact with each other, through logical analysis, exploring functions and signal flow analysis methods, we can always understand these difficult circuits.

　　In fact, there are a lot of information available for reading and using on circuit diagrams. With the reader's induction, analysis and research, you must be able to understand the whole picture. Each person's actual situation is different, the way of looking at the picture and judging may be slightly different, and the process of looking at the picture is not unchanged. With the rapid development of electronic technology, manufacturers often develop new circuits or circuits with new functions, even circuit programs are unique. Above all, we can finish the work of looking at pictures sensitively on the basis of the basic idea of looking at pictures.

The article originated from Jiangmen single-sided and double-sided circuit boards. http://www.yonghongpcb.com