Multimeter for the assessment of the good and bad skills of the electronic components
The complete circuit board contains a large number of electronic components, because of many uncertain factors, component damage is very common. When equipment failure is caused by the majority of component damage, then the detection and repair of components is very important, how to judge the quality of a component is an engineer must learn the skills.
Often in the maintenance of the first to judge the rectifier bridge pin electrode, visual alone is not able to judge, but also not enough insurance.
Use a soldering iron to remove the capacitors and resistors used for voltage reduction, as well as the rectifier bridge.
In the judgement of the rectifier bridge pin electrode, we can use the multimeter for PU aid. R × 1K gear state, with the black pen of the multimeter touch any one of the bridge piles of pins, the red pen to test the other pins. At this time, if the multimeter shows infinity, it can be judged that the black pen touches the pin for the output of the bridge stack positive pole, if the display range of 4K-10K ohms, then, the black pen touches the pin for the negative pole, the red and black pen positive and negative judgement, the rest of the pins is the AC input.
Use a multimeter to determine the positive and negative digital tube
Light-emitting digital tube is mainly designed for displaying numbers, but it is very widely used. So, in the maintenance process, how to judge whether the light-emitting digital tube is damaged?
Similarly, here can still use the multimeter detection, the use of R × 10K file and R × 100K file. First use the red nose with the digital tube "ground" lead end touch, when the black pen is measured in turn other lead end, if the test results for all segments of the light normal, then the digital tube is intact; if one of the section does not light, then the digital tube has been damaged.
Measurement of the nominal resistance of the potentiometer
When judging the potentiometer, you should measure the nominal resistance of the potentiometer first. How to measure the nominal resistance of the potentiometer?
How to measure the nominal resistance of potentiometer?
Adjust the resistance of the multimeter gear, the "2" end as a mobile contact, ohm file if the pointer does not move, the resistance value does not move, the potentiometer is damaged. Subsequently measure the potentiometer movable arm with the contact of the resistor piece whether there is a problem. You can use the multimeter ohm gear "1, 2" or "2, 3" end of the resistor shaft counterclockwise rotation to near the "off" position, that is, the smallest resistance, then Slowly rotate the shaft in the clockwise direction, the resistance slowly becomes larger, when the shaft reaches the limit position, the resistance value should be similar to the nominal value of the potentiometer.
