Circuit board factory restore circuit schematic diagram method according to PCB circuit board
According to the experience of circuit board factory, distinguish the ground wire, power cord and signal wire 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 respective ground wires to form an independent ground connection network, which can also be used as a basis for identification and judgment.
If the printed board is marked with component serial numbers (such as VD870, R330, C466, etc.), because 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 drawing should be used.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 the schematic diagram of restoring circuit.
If the component number is not marked on the printed board, it is better to number the component number 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 they design the components of printed board.After finding the core device of a unit, you can find other components of the same functional unit as long as you follow it.
In order to avoid too many connections between the pins of the 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.
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