Test electronic components with multimeter.. 50 test

HOW TO TEST SWITCH Toggle switch Rocker switch Limit Switch

All kind of switch has mechanical contacts. The most basic of contacts is NC type contact ( Normally Close ) and NO type contact ( Normally open ). Some switch has only 1 NC contact , some switch has only 1 NO contact , and some model consist of many contacts ; NO NC Common terminals. The circuit diagram of switch has printed on its body. How to check switch it depends on contact type of witch.

NC type contact ( Normally Close ) , Terminal 1 and 2 is connected

NO type contact ( Normally open ) Terminal 1 and 2 is not connected

Basic output contact form consists of NC and NO contact

Step to check switch

1. Turn rotary switch to continuity test function of digital multimeter.
2 Connect test leads to the NC contact of switch. The meter will beep if it is a good NC contact. Bad NC contact , the meter does not beep. After that change switch position by pressing to ON and OFF. The good contacts will change status from ON to OFF or OFF to ON.
3. Connect the test leads to the NO contact. The meter will not beep if it is a good NO contact. Bad NO contact , the meter will beep ( short circuit).
After that change switch position by pressing to ON and OFF. The good contact will change status from OFF to ON and ON to OFF. These changing of contact represent results on multimeter display.
4. Test every NO and NC contact set. If there is only 1 contact is bad , the switch is not good.
then find the replacement.

Test NC contact of switch , the meter will beep if it is a good NC contact.
Bad NC contact , the meter will not beep.

Then change the toggle position , the NC contact connection will change too, from beep to OL

Test NC contact of switch , the meter will beep if it is a good NC contact.

Test NC contact of switch , After changing switch position the internal contacts of switch will change too , from connected to disconnect.
Represent as beep for connected and OL display for disconnected.

Read more of testing , list of article here .

30 testing of electronic devices

Multimeter test relay

HOW TO TEST RELAY with digital multimeter

HOW TO TEST RELAY

RELAY TESTING. There are may model of relay and some model has many terminals. The terminal of relay is divided into 2 section ; Section 1 is coil , for supplying voltage to control to operate as switch ON or OFF. The coil of relay has some resistance so good coil will show some resistance when testing with ohmmeter. Section 2 is output contacts which consists of NC type contacts ( Normally Close ) and NO type contacts ( Normally open ).

NC type contact ( Normally Close ) , Terminal 1 and 2 is connected

NO type contact ( Normally open ) Terminal 1 and 2 is not connected

Basic output contacts form consist of NC and NO contact.

Step to check relay.
As you have learned from above there are to type of basic circuit of contacts , connected and open. So we will use continuity test function of digital multimer to test the contact ; connected contacts must be connected as it be and open contacts must be disconnected.
1. Switch off or unplug circuit that want to test. Make sure there is not any voltage supply to relay before testing.
2. Find circuit diagram that printed on relay then find where is the coil terminals.
3. Test coil terminals , find coil terminal of relay and connect test leads to it. On the sample terminal 13 and 14 is coil terminals of relay.
4. Turn rotary switch to resistance test function.
5. Good coil present some resistance value when measuring , but bad coil of relay display
" OL " ( open circuit )
6. Test NO and NC contacts of relay , check all set of contacts.
7. Set digital multimeter to continuity test function.
8. Connect test leads to the NC contact. The meter will beep if it is a good NC contact.
Bad NC contact , the meter does not beep.
9. Connect the test leads to the NO contact. The meter will not beep if it is a good NO contact. Bad NO contact , the meter will beep ( short).
10. Test every NO and NC contact set. If there is 1 contact is bad , the relay is not good.
then find the replacement.

Find circuit diagram of relay under test that printed on relay's body.

Test coil terminals no. 13 and 14.
Good coil must present some measured resistance value.

Test NC contact this example is terminals No. 10 and No. 2.

Connect test leads to the NC contact. The meter will beep if it is a good NC contact.

Test NO contact this example is terminals No. 10 and No. 6.
Connect test leads to the NO contact. The meter will not beep if it is a good NO contact.

How to test SCR with multimeter

https://www.testmultimeter.com/2021/11/multimeter-use-how-to-test-scr.html

How to test TRIAC

https://www.testmultimeter.com/2021/11/multimeter-use-how-to-test-triac.html

How to test Mosfet

https://www.testmultimeter.com/2021/11/multimeter-use-how-to-test-mosfet.html

Test IGBT Part 1

https://www.testmultimeter.com/2021/11/multimeter-use-how-to-test-igbt.html

Test IGBT Part 2

https://www.testmultimeter.com/2020/12/test-igbt-with-multimeter-bad-or-good.html

Test SCR Module

https://www.testmultimeter.com/2020/12/test-scr-thyristor-module-with.html

Test IGBT Module

https://www.testmultimeter.com/2020/12/how-to-to-test-igbt-module-with.html

HOW TO IDENTIFY SILICON DIODE or SCHOTTKY DIODE ?

HOW TO IDENTIFY SILICON DIODE or SCHOTTKY DIODE

Silicon Diode is the most common use but for some circuit it need a schottky diode . Schottky diode has low voltage drop and fast recovery time so it can operate with high frequency application. We know voltage drop across Silicon Diode is 0.5-0.8V and 0.1V - 0.45V for schottky diode. I have sample of both 1N5402 standard general purpose Silicon Diode , 1N5820 for schottky diode. I will measure it and present the result on this article.

1. Silicon Diode Checking.
The voltage drop across a Silicon Diode is 0.5-0.8V and on photo = 0.528V

HOW TO TEST ZENER DIODE

by digital multimeter and Analog multimeter

ZENER DIODE TESTING

ZENER DIODE TESTING Zener diode is a subtype of a diode and it use on circuit as a different function from standard diode. Standard diode we use it as forward bias mode but for Zener diode we use it as reverse bias mode on circuit. When applying forward bias to zener diode it will conduct and let current flow as standard diode , another condition when applying reverse bias to zener diode it will not let current flow until the voltage supply is over the zener breakdown voltage then it will let current flow.

Basic Circuit of zener Diode

How to check zener diode , it has more detail then checking standard diode as it is a subtype of diode so in some condition checking method is as same as standard diode. Before checking you have to know important technical detail of multimeter. We set analog multimeter to range Rx1 or Rx10 , let consider at the test lead there is 3VDC 150mA for Rx1 range and 3VDC 15mA for Rx10.

There is 3VDC 150mA at the test leads , Rx1 range, of Analog Multimeter.

POTENTIOMETER ( small) and RHEOSTAT ( big )

Potentiometer is a variable resistor . It use to adjust signal and low current on electronics circuit. It has 3 terminals. If you want a variable resistor that can handle more current, you may looking for rheostat.

Potentiometer

Rheostat

We will name as terminal 1 and 2 and 3 when measure .

Step to check Potentiometer and rheostat.
1. Read the resistance value that marks on potentiometer or rheostat.

HOW TO CONNECT and WIRE POTENTIOMETER

When we want to adjust voltage and current on circuit to get the desired value , change condition to test the circuit. We have to use potentiometer as it can vary resistance. Refer to ohm's law V = IR . If we change resistance then the value of V and I change too. The potentiometer has 3 terminals and its symbol shown below. How to wire potentiometer , it we will be explained below.

Potentiometer has 3 terminals

HOW TO TEST RESISTOR with Digital Multimeter and Analog Multimeter

RESISTOR TESTING Resistor is a basic electronic components. We have to test it when design circuit and repair equipment.

Step to measure resistor by Digital Multimeter

1. Turn power off or remove power from circuit under test. Failure to do this will cause damage to multimeter and electric shock.
2. During testing , do not touch the tip of test leads.
3. Insert black test lead to COM- jack and red test lead to VΩ jack.
4. Turn rotary switch to resistance range / resistance test function.
5. Connect the test leads to resistor under test terminals.
6. The display will show some resistance value.
Good resistor should show measured value that is close to its specification value.
Bad resistor ( open ) show "OL" ( over range ) on meter' display.
Bad resistor ( Degrade , resistance value is much increasing or decreasing ) get measured value that is much different from its original value.

0.5K ohm resistor and meter show measured value 0.491K ohm
so this is the good resistor.

Step to measure resistor by Analog Multimeter
1. Turn power off or remove power from circuit under test. Failure to do this will cause damage to multimeter and electric shock.
2. Never touch the tip of test leads while testing.
3. Plug the black test lead to - COM N jack and red test lead to + P jack.
4. Conduct 0 ohm adjustment the test leads and every time that change resistance ranges must make 0 ohm adjustment by this multimeter will provide the accurate resistance testing.
4. Turn rotary switch to resistance x 1K range ( and read 7. about select Rx )
5. Connect the test lead to resistor under test terminals.
6. Read resistance value from Ω scale
7. The good resistance ranges setting , make the pointer point in the area that easy to read scale. ( Rx1 Rx10 Rx100 Rx1K Rx10 setting )

1K range setting is not suitable for 270K ohm as the pointer point at around the edge of scale

Easy to read scale the pointer should point around this area on photo , not at the edge.

Better and suitable resistance range setting for 270K ohm is Rx 10K.
Notice the pointer point at the easy to read scale.

Good resistor should get the measured value that is closest to its specification value.
Bad resistor ( open ) will always point at ∞ resistance scale.
Bad resistor ( Degrade ,resistance value is much increasing or decreasing ) get the measured value that is much different from its original value.

8 Important Testing electronic device on this blog .

Testing electronic device IGBT testing SCR testing Triac Testing Check mosfet and more