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How to installation of new circuit board design
 
How to installation of new circuit board design

For a new circuit board design, debug, it will often encounter some difficulties, especially when the board is relatively large, relatively long elements, often can not start. However, if the master of a reasonable testing method, testing it will be much more effective. Just get it back for a new PCB board, we should first look around the board if there are problems, such as whether there are obvious cracks, with or without short-circuit, open circuit and so on. If necessary, you can check the resistance between the power supply with the ground is large enough.
Then is to install the components of the. Independent modules, if you are not sure sure they work properly, not all are equipped with the best, but part of loaded on some (for relatively small circuits that can be fitted with one), so easy to determine the fault coverage, trouble-free when received, can not start. In general, you can put the power part of the first installed, then the power supply output voltage is normal detection. If you do not have too much time on the power grasp (even if there is a great grasp, it is recommended that you add a fuse, just in case), consider using the limiting function with adjustable power supply. Good first over-current protection current default, then the voltage regulator power supply to increase slowly, and to monitor the input current, input voltage and output voltage. If the process to increase, there was no over-current protection and other issues, and the output voltage has reached the normal, then the power supply OK. On the contrary, they have to disconnect the power, find the point of failure, and repeat the above steps until the power supply to normal.
Then gradually install other modules, each module is installed, to test the power, the power is in accordance with the above steps to avoid design errors and / or installation errors which led to over-current and burn components.

General fault finding ways to have the following categories:

① Measuring voltage method. First of all, ensure that the voltage supply pin of the chip is normal, then check the various reference voltage is normal, in addition to the operating voltage of each point is normal and so on. For example, the average silicon transistor turns on, BE junction voltage at 0.7V, while the CE junction voltage in the 0.3V or so or less. If a transistor's BE junction voltage greater than 0.7V (except for special transistor, for example, Darlington, etc.), may be the BE junction to open.

② signal injection method. Will be added to the input signal source, followed by subsequent measurement of the waveform of each point to see whether it is normal to find the point of failure. Sometimes we also use a more simple way, for example, a forceps with a hand to touch input at all levels to see if the output response, which in audio, video, amplifiers are often used (but note, hot bottom circuit or high voltage circuit, can not make this method, it may cause electric shock). If you touch the former one did not respond, but after a responsive touch, then the problem is the first level, should focus on checking.

③ course, there are many other ways to find trouble spots, such as seeing, hearing, smell, touch and so on. "See" is to see whether the obvious mechanical damage to components, such as broken, burned black, deformation; "listen" is listen to the sound is normal, for example, should not affect things in the ring, where the sound does not ring or sound is not normal and so on; "smell" is to check whether there is odor, such as burning smell, the taste of the electrolyte capacitor, etc., for an experienced electronics service personnel, it is very sensitive to these smells of; "touch" is to use hand to test the device's temperature is normal, such as too hot or too cold. Some power devices, work will heat up, if the touch is cool, you basically can tell it did not work together. However, if the heat should not place hot or too hot for the hot places, that is not acceptable. General power transistor, voltage regulator chips, working in 70 degrees below is not in question. 70 degrees is about what kind of a concept? If you press your hands up, you can insist on more than three seconds to explain the temperature about 70 degrees below (note the first tentative touch, do not burn the hands.)

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