For example, you might test the resistance of the switches, relay contacts, or motor. If you are testing a circuit or even just removing a component, be sure that all power to the circuit is turned off before proceeding.
Plug the black lead into the socket labeled “COM” and the red lead into the socket labeled “ohm”.
If you don’t know the range, start with the middle range setting, usually 20 kilo-ohms (kΩ). Touch one lead to the end of your component and the other lead to the opposite end. The number on the screen will either be 0. 00, OL, or the actual value of resistance. If the value is zero, the range is set too high and needs to be lowered. If the screen reads OL (overloaded) the range is set too low and needs to be increased to the next highest range. Test the component again with the new range setting. If the screen reads a specific number such as 58, that is the value of the resistor. Remember to take into account the range applied. On a digital multimeter the upper right-hand corner should remind you of your range setting. If it has a kΩ in the corner, the actual resistance is 58 kΩ (58,000 ohms). Once you get in the right range, try lowering the range one more time to see if you can get a more accurate reading. Use the lowest range setting for the most accurate resistance readings.
For example, if your reading is . 6 and the upper right corner says MΩ the resistance of your component is 0. 6 mega-ohms.
For example, you might test the switch or motor. If you are testing a circuit or even just removing a component, be sure that all power to the circuit is turned off before proceeding.
Plug the black lead into the socket labeled “COM” and the red lead into the socket labeled “ohm”.
If you don’t know the range, start with the middle range setting, usually 20 kilo-ohms (kΩ). Touch one lead to the end of your component and the other lead to the opposite end. The needle will swing across the screen and stop in a specific spot, indicating the resistance of your component. If the needle swings all the way to the top of the range (the left side), you will need to increase the range setting, zero out the multimeter, and try again. If the needle swings all the way to the bottom of the range (the right side), you will need to decrease the range setting, zero out the multimeter, and try again. Analog multimeters must be reset or zeroed out every time the range setting is altered and before testing the component. Touch the ends of both leads together to short the circuit. Ensure the needle is set all the way to zero using the Ohms Adjustment or Zero Control after the leads have been touched to each other.
As the scale goes up, the higher values are clustered closer together. Setting the correct range is crucial to being able to get an accurate reading for your component.
For example if you had set the range to 10 Ω and the needle stopped at 9, the resistance of your component is 9 ohms.
Any capacitors in a circuit being tested for resistance should be discharged before testing. Discharged capacitors may absorb charge from the multimeter’s current, creating momentary fluctuations in the reading.
One way to keep your hands off components is to attach them to a testing board, or “breadboard” when testing for resistance. You can also attach alligator clips to the multimeter probes to keep the terminals of the resistor or component in place while testing.
