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Reverse Engineering PCB to Schematic

Hi, i’am Aidan Taylor, and is serving in the field of PCB Reverse Engineering, PCB design, and PCB clone for over 10 years.

Reverse Engineering PCB

Reverse Engineering PCB

Reverse Engineering a PCB

Reverse engineering a printed circuit board (PCB) to schematic is the art of understanding how a circuit functions by looking at its physical appearance. You’ll need to know the electrical properties of each component, as well as what type of components you’re dealing with in order to reverse engineer your PCB correctly.

To reverse engineer a PCB in this way, you will also need specialized software and access to some specialized tools that are not common household objects. It can be an intimidating process for beginners who have little experience with electronics, but it is not impossible. With the right knowledge and preparation, you too can learn how to reverse engineer your PCB to schematic.

This article will cover the following questions and concepts:

  • What is reverse engineering PCBs?
  • Why is it important?
  • How to reverse engineer PCB to schematic
  • Shopping for electronic components
  • Identifying traces for different components
A PCB schematic

A PCB schematic

What Is Reverse Engineering PCBs?

Reverse engineering PCBs involves taking a PCB diagram and converting it back into a schematic. A schematic is the original circuit diagram from which a PCB is designed. If you have an existing PCB diagram, you can perform a conventional conversion by following the rules of schematic reading.

The problem with a conventional approach is that PCBs and schematics are designed to be different. That means a conventional conversion method won’t tell you which component is connected to which trace on the PCB.

This is where reverse engineering comes into the picture. It allows you to identify components connected to each trace on the PCB.

Why Is It Important?

By understanding how the individual components are connected, you’ll be able to modify existing circuits or design PCBs from scratch. Reverse engineering also comes in handy when you’re troubleshooting faulty circuitry.

You can use a schematic to quickly find out whether a single component is faulty, or if it’s the entire circuit that’s broken. Once you have a schematic in hand, it’s much easier to find out which components are causing the issue. You can then focus your attention on the problematic components and let go of other circuits that are working correctly.

8 Steps of Reverse Engineering PCB to Schematic

To reverse engineer PCBs to schematics, you’ll need to find the components’ connections using a multimeter. A multimeter is an electrical tool used to measure electrical current and voltage. By connecting the multimeter to different points on the PCB, you’ll be able to identify the traces connected to each component.

The process is not as easy as it sounds, but it is possible if you follow the steps below.

Get a PCB, first record the models, parameters, and positions of all components on the paper, especially the direction of diodes, triodes, and the direction of IC notch. It is best to take two pictures of the component locations with a digital camera. Many PCB circuit boards are getting more and more advanced, and some of the diodes and triodes above are not visible at all.

2. Get a Scanned Image

Remove all components and remove the tin from the PAD holes. Clean the PCB with alcohol, and then put it into the scanner. When the scanner scans, you need to slightly increase the scanned pixels to get a clearer image. Then lightly polish the top and bottom layers with water gauze paper until the copper film is shiny, put it into the scanner, start PHOTOSHOP, and scan the two layers in color.

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Note that the PCB must be placed horizontally and vertically in the scanner, otherwise the scanned image will not be available.

3. Adjust the Corrected Image

Adjust the contrast and brightness of the canvas to make the part with copper film contrast strongly with the part without copper film, then turn the secondary image to black and white, check whether the lines are clear; if not, repeat this step. If it is clear, save the picture as TOP BMP and BOT BMP files in black and white BMP format. If there is any problem with the picture, you can also use Photoshop to repair and correct it.

4. Check the Position Coincidence of PAD and VIA

Convert the two files in BMP format to PROTEL format files respectively, and transfer two layers in PROTEL. For example, the positions of PAD and VIA after the two layers are basically the same, indicating that the first few steps are well done. If there is any deviation, then repeat Step 3.

5. Draw Layers

Convert the BMP of the TOP layer to the TOP PCB, pay attention to convert it to the SILK layer, which is the yellow layer, and then you can trace the line on the TOP layer, and place the device according to the drawing in the second step. After painting, delete the SILK layer. Repeat until all layers are drawn.

6. Combine Picture of Top PCB and Bottom PCB

Transfer the TOP PCB and BOT PCB in PROTEL, and combine them into one picture.

7. Laser Print Top Layer, Bottom Layer

Use a laser printer to print the top layer and bottom layer on the transparent film (1:1 ratio), put the film on the PCB, and compare whether there is any error. If it is correct, you are successful.

8. Test Your New PCB

Test whether the electronic performance of the copy board is the same as that of the original board.

Shop for Electronic Components

Once you’ve identified the components on the PCB, you need to shop for the required components. You can use an EDA software like Eagle to identify the required components. Alternatively, you can use a website like Mouser or Digi-Key to quickly search and find components.

When shopping for components, make sure you buy parts that are compatible with the PCB. You can make use of the circuit diagram to confirm that the components are compatible.

Identify Traces for Different Components

Once you’ve collected the required components, you need to identify the traces connected to each component. You can do this by connecting the multimeter to different points on the PCB. The multimeter will show you the resistance between the two points.

Once you identify the trace connected to each component, you have reverse engineered the PCB to the schematic. You can now focus your attention on the components that are causing issues.

Summing Up

Reverse engineering PCBs to schematics is an important skill to have as an engineer. With this skill, you can easily modify existing circuits or design your PCBs from scratch.

The process of reverse engineering PCBs is not easy, but it is possible. With the right tools, you can easily identify the traces connected to each component. That means you can modify existing circuits or design PCBs from scratch. With this skill, you can focus on what matters.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2022 Aidan Taylor

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