The commonly used detection methods for integrated circuits include online measurement method, non online measurement method, and substitution method

1. Non online measurement: When an integrated circuit is not soldered into the circuit, the DC resistance value between its pins is measured and compared with the known normal DC resistance value between the pins of the same type of integrated circuit to determine whether it is normal.

. 2. The online measurement method uses voltage measurement, resistance measurement, and current measurement methods to determine whether the integrated circuit is damaged by measuring the voltage, resistance, and current values of each pin of the integrated circuit on the circuit. 3. Substitution method: Substitution method is to replace the tested integrated circuit with a known intact integrated circuit of the same model and specification, which can determine whether the integrated circuit is damaged

(2) Detection of commonly used integrated circuits

1. Detection of microprocessor integrated circuits. The key test pins of microprocessor integrated circuits are VDD power supply terminal, RESET reset terminal, XIN crystal oscillator signal input terminal, XOUT crystal oscillator signal output terminal, and other line input and output terminals.

. Measure the resistance and voltage values of these key pins to ground on the road to see if they are the same as normal values (which can be found in the product circuit diagram or relevant maintenance materials). The reset voltage of RESET varies among different models of microprocessors, with some having a low-level reset, which means it is at a low level at the moment of startup and remains at a high level after reset; Some have a high-level reset, which means that it becomes high at the moment of switching and remains low after resetting 2. Detection of Switching Power Supply Integrated Circuits The key pin voltages of switching power supply integrated circuits are the power supply terminal (VCC), excitation pulse output terminal, voltage detection input terminal, and current detection input terminal. Measure the voltage and resistance values of each pin to ground. If there is a significant difference from the normal value, it can be determined that the integrated circuit has been damaged when its peripheral components are normal. A thick film integrated circuit with a built-in high-power switch tube can also determine whether the switch tube is normal by measuring the forward and reverse resistance values between the C, B, and E poles of the switch tube 3. Detection and Inspection of Audio Power Amplifier Integrated Circuit When inspecting an audio power amplifier integrated circuit, the voltage and resistance values of its power supply terminal (positive and negative power supply terminals), audio input terminal, audio output terminal, and feedback terminal to ground should be detected first. If the measured data values of each pin differ significantly from the normal values, and the peripheral components are normal, it indicates internal damage to the integrated circuit. When the power supply voltage of the audio power amplifier integrated circuit that causes silent faults is measured to be normal, the signal interference method can be used to check. When measuring, the multimeter should be placed in R × First gear, ground the red lead and touch the audio input with the black lead. Normally, there should be a strong "click" sound in the speaker. 4. Use a multimeter to measure the DC voltage range of the integrated circuit of the operational amplifier, and measure the voltage value between the output terminal of the operational amplifier and the negative power supply terminal (the voltage value is higher when static). Use handheld metal tweezers to sequentially touch the two input terminals of the operational amplifier (with interference signals added). If the multimeter needle swings significantly, it indicates that the operational amplifier is in good condition; If the multimeter needle does not move, it indicates that the operational amplifier is damaged. 5. Detection of time based integrated circuits: Time based integrated circuits contain digital and analog circuits, which are difficult to directly measure with a multimeter. The test circuit shown can be used to check the quality of the time based integrated circuit. The test circuit consists of resistive and capacitive components, LED emitting diodes, 6V DC power supply, power switch S, and 8-pin IC sockets. After inserting the time base integrated circuit (such as NE555) into the IC socket, press the power switch S. If the tested time base integrated circuit is normal, the LED will flash and light up; If the LED is not on or remains on, it indicates poor performance of the tested time base integrated circuit