The circuit board is short, and how to check is that the element burned out（part1）
This method is carried out when IC is not welded into the circuit. In general, multimeter can measure the positive and negative resistance values between the pins corresponding to the ground pins, and compare them with the intact IC.
Another is Road detection
This is a testing method for detecting the DC resistance, the AC and DC voltage and the total working current of the IC pins in the circuit (IC in the circuit) through the multimeter. This method overcomes the limitation of substitution of IC and the trouble of dismantling IC. It is the most common and practical method for detecting IC.
1. in road DC resistance detection method
This is a multimeter ohm block, directly measuring the positive and negative DC resistance values of IC pins and peripheral components directly on the printed circuit board, and comparing with normal data, we can find and determine the fault. The following three points should be paid attention to in the measurement.
(1) the power supply should be disconnected before measuring, so as to avoid damage to the meter and the components in the test.
(2) the internal voltage of the multimeter resistors must not be more than 6V, and the range of measuring range is best using R x 100 or R x 1K.
(3) when measuring the parameters of IC pins, we should pay attention to the measurement conditions, such as the type of the tested machine, the position of the sliding arm of IC related potentiometers, and the quality of the external circuit elements.