Welding methods and skills for a new PCB board

For the new PCB board, we must look at the board first, whether there are problems, such as whether there are obvious cracks, there is no short circuit, open circuit, etc.

If necessary, check if the resistance between the power supply and the ground is large enough. Then install the component. In general, the power can be installed in the first part, and then on the power supply output voltage detection is normal. If you do not have too much confidence in the grasp, it’s a good idea for adjustable regulated power supply with current limiting function. The preset is better than the current protection, and then the voltage of the power supply is slowly increased, and the input current, input voltage and output voltage are monitored. If there is no over-current protection and other issues during process, and the output voltage is also normal, then the power part OK. 

There are several ways to find fault.

Measuring voltage method

First of all, we must confirm that the power supply voltage of each chip is normal, and then check the reference voltage is normal, there are other points of the operating voltage is normal, etc.

Signal injection method

The signal source is added to the input end, and then the waveform of each point is measured in turn to see if the fault is normal to find the fault point. Sometimes we use a simpler approach, for example, with a hand holding tweezers to touch the input at all levels to see whether the output response, if you do not respond to the first level, and after the first reaction, then the problem at the previous level, should focus on inspection.

Of course, there are many other ways to find fault points, such as seeing, hearing, smelling, touching, etc.

"Look" is to see whether there are obvious mechanical damage components, such as rupture, burning black, deformation, etc.

"Listen" is to listen to the sound of the work is normal, such as something that should not ring in the ring, the sound of the place does not ring or abnormal sound, etc.

"Smell" is to check whether there is a smell, such as the smell of burning, the taste of electrolytic capacitors, etc., for an experienced electronic maintenance personnel, the smell is very sensitive.

"Touch" is to use the hand to test whether the device temperature is normal, such as too hot, or too cold. Some power devices, should fever when work, but if it is cold, it can be judged that it does not work. General power transistor, voltage regulator chip, working at 70 degrees below is completely no problem.