( a ) common detection method
The commonly used integrated circuit detection method has the online measurement, non online measurement method and substitution method.
1 of online measurement of non online measurement of tide in the integrated circuit is not welded in the circuit, by measuring the DC resistance between pins with known normal models with integrated circuit pin between the DC resistance values were compared, to determine whether it is normal.
2 online measurement on line measurement method is the use of voltage measurement, resistance measurement and the current measurement method, the measurement circuit on the integrated circuit pin voltage, resistance value and the current value is normal or not, to determine whether the integrated circuit is damaged.
3 substitution method substitution is the use of known good models with the same specifications, integrated circuit to replace the measured integrated circuit, the integrated circuit can judge whether the damage.
( two) commonly used in integrated circuit testing
The 1 microprocessor integrated circuit testing microprocessor integrated circuit test key pin is VDD power supply, RESET, XIN oscillator reset end signal input end, a signal output end of XOUT crystal and other various line input, output. In measuring these critical resistance value of the foot on the ground and voltage value, see if with normal values ( from the product circuit or the repair information found in the same ). Different models of the RESET microprocessor reset voltage is not the same, some low level reset, namely in the instant of the low level, reset after sustaining a high level; some are high level reset, namely in the switching moment is at a high level, low level reset.
The 2 switching power supply IC detection switch power IC key pin voltage is power terminal (VCC ), pulse output, voltage detection input terminal, a current detection input terminal. Measurement of the pin to ground voltage and the resistance value, and if the normal value of difference, in the peripheral components under normal circumstances, can determine whether the integrated circuit has been damaged. Built in large power switch tube in the thick film integrated circuit, but also can be measured through a switching tube C, B, E pole between the positive, reverse resistance value, to determine whether the normal switching tube.
The 3 audio power amplifier integrated circuit check audio power amplifier integrated circuit, it should detect its power terminal ( a positive power end and a negative power supply terminal ), audio input, audio output end and a feedback end of the voltage and the resistance value. If the measured data values associated with each pin of the normal value of difference, the peripheral components and normal, is the integrated circuit internal damage. On the fault caused by silent audio power amplifier integrated circuit, measurement of the power supply voltage is normal, the available signal interference method to check. When measuring, the multimeter should be placed in the R x 1 archives, the red pen grounding, with a black pen touch audio input, normal speakers should be strong" Titicaca" sound.
The 4 operational amplifier integrated circuit test using a multimeter DC voltage, measurement of operational amplifier output end and a negative power supply terminal voltage value between ( in a static voltage value is high ). Using hand-held metal tweezers touch operation in a two input terminal of the amplifier ( interference signal is added ), if the multimeter hand greatly swing, the operational amplifier in good condition; if the multimeter pointer does not move, the operational amplifier has been damaged.
5 time base integrated circuit to detect a time-base integrated circuit includes digital circuit and analog circuit, the multimeter is difficult to directly measure the good from the bad. Can be used as shown in Figure 9-13 test circuit to detect a time-base integrated circuit quality. The test circuit is composed of a resistance-capacitance elements, light emitting diode LED, 6V DC power supply, power supply switch S and a 8 foot IC sockets. The time-base integrated circuit ( for example NE555 ) letter inserting IC socket, press the power switch S, if the measured time base integrated circuit is normal, then the light emitting diode LED will shine; if LED does not light or bright all the time, then the measured time base integrated circuit performance is bad.
