First, the resistance test method, the multimeter transferred to the resistance file, a normal circuit board to detect a point to the ground resistance, and then detect another piece of the same circuit board uniform point of the test and the normal resistance value is different, If different to determine the scope of the problem.
Second, the voltage detection method, the multimeter transferred to the voltage file to detect the suspected circuit of a certain point to the ground voltage, compared with the normal value is similar, you can easily determine the scope of the problem.
Third, the pressure drop detection method, the multimeter transferred to the diode voltage drop detection file, because all the IC are composed of a large number of basic components, but miniaturization, so when it has a pin on the smooth flow of smooth , There will be voltage drop on the pin. General uniform type of IC on the same pin on the voltage drop is similar, according to the pin on the pressure drop value is good or bad, to be in the case of circuit power control.
Four, short-circuit detection method, the multimeter transferred to the short-circuit detection block (generally with alarm function, such as conduction is issued a cry), to detect whether there is a short circuit phenomenon, found immediately after the short circuit should be resolved, short circuit is the most common The led display module failure. Some can be found by observing the IC pin and pin pin. Short circuit detection should be in the case of circuit power to avoid damage to the multimeter. This method is the most commonly used method, simple and efficient. 90% of the faults can be detected by this method.