The first short circuit detection method:

Set the multimeter to the short-circuit detection position (generally with an alarm function, if it is turned on, it will beep), check whether there is a short-circuit phenomenon, and solve it immediately after it is found. The short-circuit phenomenon is also the most common LED display module failure. Some can be found by observing the IC pins and header pins. The short circuit detection should be operated when the circuit is powered off to avoid damage to the multimeter. This method is the most commonly used method, simple and efficient. 90% of faults can be detected and judged by this method.

The second resistance detection method:

Adjust the multimeter to the resistance position, check the resistance value of a certain point of a normal circuit board to ground, and then check the same point of another same circuit board to test whether the resistance value is different from the normal resistance value, if it is different, it is determined The scope of the problem.

The third voltage detection method:

Adjust the multimeter to the voltage range, check the ground voltage at a certain point of the circuit suspected of having a problem, and compare whether it is similar to the normal value, which can easily determine the scope of the problem.

The fourth pressure drop detection method:

Adjust the multimeter to the diode voltage drop detection gear, because all ICs are composed of many basic single components, but they are miniaturized, so when there is a current passing through a pin of it, it will exist on the pin. Voltage drop. Generally, the voltage drop on the same pin of the same type of IC is similar. According to the voltage drop value on the pin, it must be operated when the circuit is powered off.