In PCB reverse engineering, the reverse deduction of a schematic refers to the process of reconstructing the PCB circuit diagram either by inverting the existing PCB documentation or by directly drawing the schematic based on the physical product. The primary goal is to explain the operating principles and the functional state of the circuit board. Additionally, the schematic is used to analyze the product’s functional characteristics. In contrast, during forward design, a schematic is typically created first, followed by the PCB layout design based on the schematic.
Whether used for analyzing the principles of a circuit board and the operational characteristics of a product in reverse engineering or as the foundational step in forward design for PCB layout, the schematic plays a crucial role. Thus, how to reverse engineer a PCB schematic from the document or the physical object, and what specific details must be attended to during this process?
1. **Properly Divide Functional Areas**
When performing reverse design of the PCB schematic, effectively dividing the functional areas can significantly help engineers avoid unnecessary complications and improve the drawing efficiency. Typically, components with similar functions on a PCB are grouped together in a concentrated manner, allowing for clear and accurate identification of functional areas when reconstructing the schematic. However, this division is not arbitrary; it requires engineers to have a solid understanding of electronic circuit principles. The process begins by identifying the core components of a functional unit, followed by locating other components of the same unit based on the trace connections to form the functional zones. This division is the foundation of the schematic. Additionally, don’t forget to reference the component serial numbers on the board, as they can expedite the functional partitioning process.
2. **Identify the Reference Points**
1. **Reference Components: The Foundation of PCB Schematic Design**
This reference component can also be considered the core element when starting the PCB copy process from the schematic diagram. By selecting reference components and creating the layout based on their pins, the accuracy of the schematic can be significantly improved. For engineers, identifying the reference component is not a particularly complex task. Typically, the component that plays a key role in the circuit is chosen as the reference. These components are usually larger and have more pins, which makes the design process easier. Examples of suitable reference components include integrated circuits, transformers, and transistors.
2. **Correctly Identify and Route Different Types of Wires**
To properly distinguish between ground, power, and signal lines, engineers must be well-versed in power supply principles, circuit connections, PCB routing techniques, and more. The differences between these types of wires can be assessed by looking at the component connections, the width of the copper traces, and the characteristics of the electronic product itself. In the schematic, to prevent wire overlap and clutter, ground lines can be represented using dedicated ground symbols. Various types of lines can be clearly differentiated by using distinct colors, while special symbols can be applied to different components. In some cases, individual unit circuits may even be drawn separately and later combined.
3. **Understand the Basic Framework and Learn from Similar Schematic Designs**
Engineers must be familiar with basic electronic circuit frameworks and schematic drawing techniques. This knowledge is essential not only for designing simple, classic unit circuits but also for constructing the overall structure of an electronic circuit. Furthermore, it’s important to recognize that similar electronic products often share common elements in their schematic diagrams. Engineers can leverage this similarity by studying existing circuit diagrams, using their experience to reverse-engineer the schematic for new products.
4. **Review and Optimize the Design**
After completing the schematic diagram, it’s essential to conduct thorough testing and validation to finalize the reverse design of the PCB schematic. Particular attention should be given to optimizing component values that are sensitive to PCB layout parameters. The schematic should be compared with the PCB file diagram to ensure full consistency. If any discrepancies are found during the inspection, adjustments must be made until the schematic is accurate, clear, standardized, and meets all design requirements.
Whether used for analyzing the principles of a circuit board and the operational characteristics of a product in reverse engineering or as the foundational step in forward design for PCB layout, the schematic plays a crucial role. Thus, how to reverse engineer a PCB schematic from the document or the physical object, and what specific details must be attended to during this process?
1. **Properly Divide Functional Areas**
When performing reverse design of the PCB schematic, effectively dividing the functional areas can significantly help engineers avoid unnecessary complications and improve the drawing efficiency. Typically, components with similar functions on a PCB are grouped together in a concentrated manner, allowing for clear and accurate identification of functional areas when reconstructing the schematic. However, this division is not arbitrary; it requires engineers to have a solid understanding of electronic circuit principles. The process begins by identifying the core components of a functional unit, followed by locating other components of the same unit based on the trace connections to form the functional zones. This division is the foundation of the schematic. Additionally, don’t forget to reference the component serial numbers on the board, as they can expedite the functional partitioning process.
2. **Identify the Reference Points**
1. **Reference Components: The Foundation of PCB Schematic Design**
This reference component can also be considered the core element when starting the PCB copy process from the schematic diagram. By selecting reference components and creating the layout based on their pins, the accuracy of the schematic can be significantly improved. For engineers, identifying the reference component is not a particularly complex task. Typically, the component that plays a key role in the circuit is chosen as the reference. These components are usually larger and have more pins, which makes the design process easier. Examples of suitable reference components include integrated circuits, transformers, and transistors.
2. **Correctly Identify and Route Different Types of Wires**
To properly distinguish between ground, power, and signal lines, engineers must be well-versed in power supply principles, circuit connections, PCB routing techniques, and more. The differences between these types of wires can be assessed by looking at the component connections, the width of the copper traces, and the characteristics of the electronic product itself. In the schematic, to prevent wire overlap and clutter, ground lines can be represented using dedicated ground symbols. Various types of lines can be clearly differentiated by using distinct colors, while special symbols can be applied to different components. In some cases, individual unit circuits may even be drawn separately and later combined.
3. **Understand the Basic Framework and Learn from Similar Schematic Designs**
Engineers must be familiar with basic electronic circuit frameworks and schematic drawing techniques. This knowledge is essential not only for designing simple, classic unit circuits but also for constructing the overall structure of an electronic circuit. Furthermore, it’s important to recognize that similar electronic products often share common elements in their schematic diagrams. Engineers can leverage this similarity by studying existing circuit diagrams, using their experience to reverse-engineer the schematic for new products.
4. **Review and Optimize the Design**
After completing the schematic diagram, it’s essential to conduct thorough testing and validation to finalize the reverse design of the PCB schematic. Particular attention should be given to optimizing component values that are sensitive to PCB layout parameters. The schematic should be compared with the PCB file diagram to ensure full consistency. If any discrepancies are found during the inspection, adjustments must be made until the schematic is accurate, clear, standardized, and meets all design requirements.
