Multimeter integrated circuit test method
1. Off-line measurement
Non-online measurement tide in the integrated circuit is not welded into the circuit, by measuring the DC resistance between its pins and the known normal DC resistance between the pins of the same type of integrated circuits for comparison to determine whether it is normal.
2. On-line measurement
Online measurement method is the use of voltage measurement, resistance measurement and current measurement method, etc., through the circuit to measure the IC's voltage value of the pins, resistance value and current value is normal, to determine whether the IC is damaged.
3. Substitution method
Substitution method is known to be intact with the same type, the same specifications of the integrated circuit to replace the measured integrated circuit, you can determine whether the integrated circuit is damaged.
4. Total current measurement method
The method is through the detection of the total current of the ic power supply into the line, to judge the ic a good or bad method. As the vast majority of the ic internal direct coupling, ic damage (such as a pn junction breakdown or open circuit) will cause saturation and cut-off of the back stage, so that the total current changes. So by measuring the total current method can judge the good and bad ic. Can also be used to measure the voltage drop in the resistance of the power supply path, using Ohm's law to calculate the total current value.
We know that the use of integrated blocks, there is always a pin with the printed circuit board on the "ground" line is welded through the circuit is called the ground pin. As integrated circuits are used within the direct coupling, therefore, the other pins of the integrated block and the ground foot between the existence of a determined DC resistance, this determination of the DC resistance known as the foot of the internal equivalent DC resistance, referred to as R within. When we get a new integrated block, you can use a multimeter to measure the internal equivalent DC resistance of the pins to determine its good or bad, if the pins of the internal equivalent resistance R in line with the standard value, the integrated block is good, and vice versa if the difference between the standard value is too large, indicating that the integrated block of internal damage.
Measurement must be noted that, as a result of the integration of a large number of internal transistors, diodes and other non-linear components, in the measurement of a single resistance value can not judge its good or bad, it must be interchanged with the pen and then measured again, to obtain the positive and negative resistance value of the two. Only when the positive and negative resistance within the R are in line with the standard, in order to conclude that the integrated block is intact.
According to the actual maintenance experience, in the road to detect the integrated circuit internal DC equivalent resistance can not be welded down from the circuit integrated block, just the voltage or in the way resistance abnormal feet and circuit disconnect, while the ground foot also disconnected from the circuit board, the other feet to maintain the original state, measured between the test foot and the ground foot of the R within the positive and negative resistance can be judged to be good or bad.
