1. Debugging a newly designed circuit board often presents challenges, particularly when the board is large and contains numerous components, making it difficult to initiate the process. However, mastering a set of effective debugging techniques can lead to significant improvements in efficiency.

2. Upon receiving a new PCB, the first step is to visually inspect the board for any apparent issues, such as visible cracks or signs of short circuits and open circuits. If needed, verify that the resistance between the power supply and ground is sufficiently high.

3. Next, proceed with the installation of the PCB components. For independent modules, if you are uncertain about their functionality, it’s advisable to install them incrementally rather than all at once (for smaller circuits, full installation is acceptable). This method helps narrow down the potential fault areas and simplifies troubleshooting.

4. Typically, it is best to install the power supply first and power it on to check whether the output voltage is within normal limits. If there’s any uncertainty during this process, even if you feel confident, it’s prudent to incorporate a fuse as a precaution. Alternatively, consider using an adjustable regulated power supply with a current limiting feature to mitigate risks.



First, set the overcurrent protection threshold, then gradually increase the voltage of the regulated power supply while monitoring the input current, input voltage, and output voltage. If no overcurrent protection or other issues arise during the voltage increase, and the output voltage stabilizes at normal levels, the power supply is functioning correctly. If problems persist, disconnect the power supply, identify the fault, and repeat these steps until normal operation is achieved.

Next, progressively install additional modules. Each time a module is added, power on and conduct tests. When powering on, adhere to the aforementioned steps to prevent overcurrent and component burnout caused by design or installation errors.

There are several methods for fault detection:

1. **Voltage Measurement Method**: Begin by checking the voltage at the power supply pins of each chip to ensure they are normal. Next, verify that all reference voltages and operating voltages at each point are correct. For instance, when a standard silicon transistor is activated, the base-emitter (BE) junction voltage should be approximately 0.7V, while the collector-emitter (CE) voltage should be around 0.3V or lower. If the BE junction voltage exceeds 0.7V (excluding special transistors like Darlington pairs), this may indicate an open junction.

2. **Signal Injection Method**: Apply a signal source to the input terminal and measure the waveform at each point sequentially to identify faults. Simpler techniques can also be employed, such as using tweezers to touch the input terminals at different levels to check for output responses. This is common in audio and video amplification circuits (note: avoid this method with high-voltage circuits to prevent electric shock). If there is no response at one level but a response at the next, the issue likely lies with the preceding level.

3. **Additional Fault Detection Methods**: Other approaches include visual inspection, listening, smelling, and touching. “Look” involves checking for visible mechanical damage on the PCB components, such as cracks or burns. “Listen” entails noting if the operational sounds of the PCB are as expected; any unexpected noises or silence where there should be sound could indicate an issue. “Smell” focuses on detecting unusual odors, such as burning or capacitor electrolyte smells; experienced technicians often have heightened sensitivity to these scents. “Touch” involves assessing whether the temperature of the components feels normal—if a device is too hot or too cold. Some power devices will heat up during operation; if they feel cold, they likely aren’t functioning. Conversely, if areas that shouldn’t be hot are, or if they are excessively hot, this also indicates a problem. Generally, for power transistors and voltage regulator chips, a working temperature below 70 degrees Celsius is acceptable. As a guideline, if you can hold your hand against it for more than three seconds, the temperature is likely below this threshold (always touch cautiously to avoid burns).

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