By diode testing mode Set your meter to the continuity / diode "bleep" test. Connect the red meter lead to the base of the t...
01:11:00
By diode testing mode
Set your meter to the continuity / diode "bleep" test. Connect the red meter lead to the base of the transistor. Connect the black meter lead to the emitter. A good NPN transistor will read a junction drop voltage of between 0.45v and 0.9v. A good PNP transistor will read "OL". Leave the red meter lead on the base and move the black lead to the collector. The reading should be the same as the previous test. Reverse the meter leads in your hands and repeat the test. Now connect the black meter lead to the base of the transistor. Connect the red meter lead to the emitter. A good PNP transistor will read a junction drop voltage of between 0.45v and 0.9v. A good NPN transistor will read "OL". Leave the black meter lead on the base and move the red lead to the collector. The reading should be the same as the previous test. Finally place one meter lead on the collector, the other on the emitter. The meter should read "OL". Reverse your meter leads. The meter should read "OL". This is the same for both NPN and PNP transistors. With the transistors on a pcb in circuit, you may not get an accurate reading, as other things in the circuit may affect it, so if you think a transistor is suspect from the readings you have got, remove it from the pcb and test it out of circuit, repeating the above procedure. OL = Open Line
By resistance checking method Multimeter wires connected across the leads and measure the resistance. In forward bias the resistance...
01:05:00
By resistance checking method
Multimeter wires connected across the leads and measure the resistance. In forward bias the resistance is low and in reverse bias condition resistance is high. If the diode shows almost zero resistance,the diode is shorted and if the resistance is very high, the diode is open. By diode testing mode Fix multimeter to diode testing mode.And measure diode drop across it. If it shows 0.3 or 0.5-0.7 in forward bias condition the diode is normal.
In the case of zener diode the reading will be same for both forward and reverse bias condition. Because zener diode conducts in both directions.
Using Resistsnce testing method Set multimeter to resistance checking.Resistor has no polarity. Check the resistance by connecting +...
00:44:00
Using Resistsnce testing method
Set multimeter to resistance checking.Resistor has no polarity. Check the resistance by connecting +ve end of multimeter to one end of resistor and -ve wire to other end. Also calculate the resistance of resistor by using color code.Compare both reading and replace resistor if the readings are different. Checking open circuited resistors If a resistor is reading a very high resistance, above its rated value, it is open. It is defective and, thus, should be replaced. Checking shorted resistors Shorted means zero resistance.If multimeter reading is zero or very low,the resistor is shorted. Another method to check short by circuit continuity test in diode mode
Test a Capacitor with an Ohmmeter of a Multimeter A very good test you can do is to check a capacitor with your multimeter set on th...
00:22:00
Test a Capacitor with an Ohmmeter of a Multimeter
A very good test you can do is to check a capacitor with your multimeter set on the ohmmeter setting. By taking the capacitor's resistance, we can determine whether the capacitor is good or bad. To do this test, We take the ohmmeter and place the probes across the leads of the capacitor. The orientation doesn't matter, because resistance isn't polarized. If we read a very low resistance (near 0Ω) across the capacitor, we know the capacitor is defective. It is reading as if there is a short across it. If we read a very high resistance across the capacitor (several MΩ), this is a sign that the capacitor likely is defective as well. It is reading as if there is an open across the capacitor. A normal capacitor would have a resistance reading up somewhere in between these 2 extremes, say, anywhere in the tens of thousands or hundreds of thousand of ohms. But not 0Ω or several MΩ. This is a simple but effective method for finding out if a capacitor is defective or not.
Test a Capacitor with a Multimeter in the Capacitance Setting
Another check you can do is check the capacitance of the capacitor with a multimeter, if you have a capacitance meter on your multimeter. All you have to do is read the capacitance that is on the exterior of the capacitor and take the multimeter probes and place them on the leads of the capacitor. Polarity doesn't matter. This is the same as the how the setup is for the first illustration, only now the multimeter is set to the capacitance setting. You should read a value near the capacitance rating of the capacitor. Due to tolerance and the fact that (specifically, electrolytic capacitors) may dry up, you may read a little less in value than the capacitance of the rating. This is fine. If it is a little lower, it is still a good capacitor. However, if you read a significantly lower capacitance or none at all, this is a sure sign that the capacitor is defective and needs to be replaced. Checking the capacitance of a capacitor is a great test for determining whether a capacitor is good or not.
Test a Capacitor with a Voltmeter
Another test you can do to check if a capacitor is good or not is a voltage test. Afterall, capacitors are storage devices. They store a potential difference of charges across their plate, which are voltages. The anode has a positive voltage and the cathode has a negative voltage. A test that you can do is to see if a capacitor is working as normal is to charge it up with a voltage and then read the voltage across the terminals. If it reads the voltage that you charged it to, then the capacitor is doing its job and can retain voltage across its terminals. If it is not charging up and reading voltage, this is a sign the capacitor is defective.
