Detection method of integrated circuit using multimeter as detection tool
Although integrated circuit replacement is convenient, disassembly is more troublesome after all. Therefore, before dismantling, it should be accurately judged whether the integrated circuit is indeed damaged and the degree of damage, so as to avoid blind disassembly. This article introduces the methods and precautions of off-road and on-road detection integrated circuits that only use a multimeter as a detection tool. The four methods of on-line detection described in the article (measurement of DC resistance, voltage, AC voltage and total current) are practical and commonly used detection methods in amateur maintenance. Here, I also hope that you can provide other practical (integrated circuits and components) discrimination and testing experience.
1. Off-road detection This method is carried out when the IC is not welded into the circuit. Generally, a multimeter can be used to measure the forward and reverse resistance values of each pin corresponding to the ground pin, and compare it with the intact IC. .
2. In-circuit detection This is a detection method that uses a multimeter to detect the DC resistance of each pin of the IC (the IC is in the circuit), the AC and DC voltage to the ground, and the total operating current. This method overcomes the limitations of replacing the IC and the trouble of disassembling the IC in the substitution test method, and is the most commonly used and practical method for detecting ICs.
1. In-circuit DC resistance detection method This is a method to use the ohm block of a multimeter to directly measure the positive and negative DC resistance values of each pin of the IC and peripheral components on the circuit board, and compare it with the normal data to find and determine the fault. .
Pay attention to the following three points when measuring:
(1) Disconnect the power supply before measurement to avoid damage to the meter and components during the test. the
(2) The internal voltage of the electric block of the multimeter shall not be greater than 6V, and the range is preferably R×100 or R×1k. the
(3) When measuring IC pin parameters, attention should be paid to the measurement conditions, such as the tested model, the position of the sliding arm of the potentiometer related to the IC, etc., and the quality of the peripheral circuit components should also be considered.
2. DC working voltage measurement method This is a method of measuring the DC supply voltage and the working voltage of peripheral components with the DC voltage block of the multimeter under the condition of power on; detecting the DC voltage value of each pin of the IC to the ground, and comparing it with the normal value, Then compress the fault range and find out the damaged components.
