1. The experience from the circuit board factory is to select large components, pins, and play a major role in the circuit, such as integrated circuits, transformers, transistors, etc., drawing the reference parts, and then starting from the selected pin drawings of the reference parts, can reduce errors, error prevention is also very important in the manufacturing industry.
2. If the printed board is marked with component serial Numbers (such as VD870, R330, C466, etc.), as these serial Numbers have specific rules, the first Arabic numeral after the English letter of the same component belongs to the same functional unit, so the drawing should be taken advantage of.Correctly distinguishing the components of the same functional unit is the basis of drawing layout. Many methods of circuit board manufacturing in circuit board factory can be applied in restoring circuit schematic diagram.
3. If the serial number of components is not marked on the printed board, it is better to number the components by yourself for the convenience of circuit analysis and proofreading.In order to make copper foil go the shortest way, circuit board manufacturers generally arrange the components of the same functional unit in a relatively concentrated way when designing PCB components arrangement.After finding the core device of a unit, you can find other components of the same functional unit as long as you follow it.
4. According to the experience of circuit board factory, correctly distinguish the ground wire, power cord and signal cord of printed board.Take the power circuit as an example. The negative end of the rectifier tube connected to the secondary of the power transformer is the positive pole of the power supply. Generally, there is a large capacity filter capacitor connected with the ground wire.The power line and ground wire can also be found from the pin of the three-terminal voltage regulator.Circuit board factory in PCB wiring, in order to prevent self-excitation, anti-interference, the ground wire copper foil is generally set to the widest (high frequency circuit is often large area of ground copper foil), power line copper foil second, signal wire copper foil is the narrowest.In addition, in electronic products with both analog and digital circuits, the printed board often separates the ground wires to form an independent grounding network, which can also be used as a basis for identification and judgment.
5. In order to avoid too many connections between the pins of components, the wiring of the circuit diagram will be crossed and interwoven, which will lead to the chaos of the drawn diagram. Terminal marks and grounding symbols can be widely used for power supply and ground wires.If there are more components, you can also draw the circuit of each unit separately, and then combine together.
6. When sketching, it is recommended to use transparent tracing paper and use multi-color pen to draw ground wire, power cord, signal wire, components and so on according to color classification.When modifying, gradually deepen the color, so that the drawing is visual and eye-catching, so as to analyze the circuit.
7. Familiar with the basic form and classical drawing of some unit circuits, such as rectifier bridge, voltage regulator circuit and operational amplifier, digital integrated circuit, etc.Firstly, the circuit of these units is drawn directly to form the frame of circuit diagram, which can improve the drawing efficiency.
8 draw circuit diagram, should as far as possible to find similar products circuit diagram as a reference, will play a double effect with half the effort, our circuit board factory and circuit board manufacturers all over the world is based on such a method to restore the schematic circuit diagram.
