PCB Board Debugging Method

For a newly designed circuit board, debugging often encounters some difficulties, especially when the board is relatively large and there are many components, it is often impossible to start. But if you master a set of reasonable debugging methods, debugging will get twice the result with half the effort.

PCB Board Debugging Steps:
1. For new PCB board that has just been taken, we must roughly observe whether there are problems on the board, such as whether there are obvious cracks, whether there are short circuits, open circuits, etc. If necessary, check whether the resistance between the power supply and the ground wire is large enough.

2. Then install components. For independent modules, if you are not sure that they are working properly, it is best not to install all of them, but to install part by part (for relatively small circuits, you can install them all at once), so that it is easy to determine the fault range. Avoid encountering problems.

Generally speaking, you can install the power supply, and then power on to check whether the output voltage of the power supply is normal. If you do not have much confidence when powering up (even if you are sure, it is recommended that you add a fuse, just in case), you can consider using an adjustable regulated power supply with current limiting function.

Preset the overcurrent protection current, then slowly increase the voltage value of the regulated power supply, and monitor the input current, input voltage, and output voltage. If there is no overcurrent protection and other problems during the upward adjustment, and the output voltage has reached normal, the power supply is OK. Otherwise, disconnect the power supply, find the fault point, and repeat the above steps until the power supply is normal.

3. Next, install other modules gradually. After each module is installed, power on and test it. When powering on, follow the above steps to avoid over-current caused by design errors and/or installation errors and burn out components.

The Way to Find The Faulty PCB Board:

1. Find faulty PCB board by measuring voltage method

The first thing to confirm is whether the voltage of the power supply pins of each chip is normal, and then check whether the various reference voltages are normal, and whether the working voltage of each point is normal. For example, when a general silicon transistor is turned on, the BE junction voltage is about 0.7V, while the CE junction voltage is about 0.3V or less. If the BE junction voltage of a transistor is greater than 0.7V (except for special transistors, such as Darlington, etc.), it may be that the BE junction is open.

2. Signal injection method to find faulty PCB board

Add the signal source to the input terminal, and then measure the waveform of each point in turn to see if it is normal to find the fault point. Sometimes we also use simpler methods, such as holding a tweezers with our hands and touching the input terminals of all levels to see if the output terminal responds. This is very common in audio, video and other amplifier circuits.