Video of How To Use A Multimeter For Electronic Testing

Introduction

This video will teach you easy-to-understand examples of how to complete testing safely with your Multimeter. 

CAUTION: A Multimeter is a very important tool in the troubleshooting of electronics. When used properly it can pinpoint problems with ease. If used incorrectly it can be very dangerous to the user and, or, the equipment being tested!

Digital Multimeters come in various forms and specifications. To cover most scenarios, you should have one with the following capabilities. DC and AC Volts, Ohms, Continuity, AC and DC Current. Manual range meters are most readily available. Auto range meter is the easiest to use. You will still need to set the meter to the proper setting, but the scale will automatically adjust to the needed range for the value measured. In the following examples, we show several different meters in hopes of helping with whatever type of meter you have.

NOTE: If your meter does not have the settings or symbols we discuss, consult the owner’s manual to verify its capability to test the circuit in question.

Adjusting Your Meter For Testing

• To properly adjust your Multimeter, you must first know what you are testing for and the value you are trying to verify. Without this information, you can damage the circuit and or your meter permanently.
• To find where to install each probe, start by determining the setting and range required for the test.
• Then you will need to make sure you have the leads (probes) plugged in correctly for the mode you are set for.
  • Some meters will only have one pair of sockets for the leads.
  • Others will have several options.
  • You will have to use your manual to verify which ports to connect the leads to

    • In some cases, the symbols will be on the sockets (ports). Using those symbols you can determine the proper configuration.

CAUTION: Never short (cross) the probes to each other! Never touch the exposed part of the probes! Never touch any exposed conductor while testing live circuitry.

Continuity

NOTE: For continuity testing, remove all power from the circuit and let it set for a short time to prevent issues.

For Continuity Testing with a Multimeter

• Verify your Red lead is in the "Continuity" socket. If your meter does not have one, use the "Ohms" socket. The Black lead goes to the "Com" Socket.

Continuity is a good test for finding any shorts or opens in a circuit. Continuity is a yes or no scenario. Which means either:

• Yes, there is a connection (continuity). In this case, the meter will show a value, beep, or both.
• Or No, there is no Continuity. In this case, the meter will show one “1” on the far left of the screen or an "OL" for overload or open loop (opinions vary).

Any value other than a "1" or "OL" indicates there is a connection between the two points the probes are touching.

When your Multimeter is set to Continuity, if you short (cross) the leads the meter will beep or show a low value. This indicates there IS continuity. This does not rule out shorts, because you can have continuity to more than one conductor.

In the next example, we are using a wire that is fifteen feet long and trying to determine if the wire is broken inside the insulation. Using your meter set to "Continuity" or "Ohms" can make this a quick test by simply touching each end with a probe to check for continuity.

In the next example, we use a wire loom that is several conductors (wires) inside the same insulator.

• You can perform the Continuity test to verify each conductor is continuous and also check for shorts from one conductor to another. Just touch one probe to one end of any conductor and then touch the other probe to all the conductors at the opposite end of the wire loom. Only one conductor should beep or give a value.
  

  • If none of the conductors beep or show a value then the conductor being probed is not continuous.
  • If more than one of the conductors beeps or shows a value there is a short in the wire loom.

NOTE: When performing this type of test on a wire loom while it is installed, be sure to check all conductors to the frame as well. Continuity to the frame indicates a short to the frame unless the conductor being tested is the ground pin.

Resistance

NOTE: Resistance testing is also completed with no power to the circuit and you must have at least one end disconnected from any circuits.

For Resistance Testing with a Multimeter

• Make sure the Red lead is plugged into the socket marked "Ohms" and the Black lead is in the socket marked "Com"
• The meter should be set to the "Ohms" setting
• In this example, we used a .5 Ohm resistor. So our meter was set to 200 Ohms which was the lowest "Ohms" setting

DC Voltage

For DC Voltage Testing with a Multimeter

• Plug the Red lead into the "Voltage" socket and the Black lead into the "Com" socket
• Set the meter to the "DC Volts" setting one range above the value you are looking for
• Our meter has a 2 Volt (2 VDC) and a 20 Volt (20 VDC) range
  • For any circuits that are from 2 Volts up to 20 Volts use the 20 VDC range
  • For something that is 1.5 VDC, for instance, a "AA" battery, use the 2 VDC range for testing
  • For testing above 20 VDC use the Range over 20 VDC, in most cases, this is a 200 VDC range

AC Voltage

For Testing AC Voltage with a Multimeter

• Plug the Red lead into the Socket marked "V" for "Voltage" and the Black probe in the socket marked "Com"
• For AC Volts set your meter to the "AC Voltage" setting
  • One range above the reading you are looking for
    • So, for verifying 110 VAC from the wall, use the "200 VAC" range (setting)

DC Current

For Testing DC Current with a Multimeter

• Place the Black probe into the "COM" socket
• Place the Red probe into the "Current" socket
• Set your Multimeter to the "DC Current" setting as your testing requires.
  • Always start testing with the highest range first

NOTE: Some meters have separate sockets for Amps and for MilliAmps. If the value is small enough, you may have to change the Red probe to the MilliAmp socket (If your meter is equipped).

• To test for Current with the probes, you will have to put your meter into the circuit in series. This means you will need to open the circuit somehow and connect one probe to one end of the circuit and the other probe to the other end of the circuit.
• When using a clamp meter for a DC Current test
  • Verify you have the meter set to DC Current and place one conductor inside the clamp

REMEMBER: To test for Current, the circuit must have power so do not short the probes or touch any exposed conductors!

AC Current

For Testing AC Current with a Multimeter

• Plug the Black probe into the "Com" socket
• Plug the Red probe into the "Current" socket
  • Some meters have separate sockets for "Amps" and for "MilliAmps". If the value is small enough, then change the probe to the "MilliAmp" socket
• Set your meter for the correct "AC Current" setting as your testing requires
  • Always start testing with the highest range first

• To test for Current with the probes, you will have to put your meter into the circuit in series. This means you will need to open the circuit somehow and connect one probe to one end of the circuit and the other probe to the other end of the circuit.
• When using a clamp meter for a Current test
  • Verify you have the meter set to "AC Current" setting and place one conductor inside the clamp

REMEMBER: To test for Current, the circuit must have power so do not short the probes or touch any exposed conductors!