1. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Multimeters Testing for continuity

2. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Continuity Testing Continuity testing allows a technician to see if a circuit is complete or not. Continuity testing is related to resistance. This is a very important concept. When a wire, switch or other device is said to have continuity, it usually means that the wire or switch is good.

3. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Step 1 Move the selector switch to the continuity setting.

4. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Step 2 Remove the insulation from the ends of a piece of hookup wire. Touch the test probes to the ends of the wire. If the wire is good, you should hear a beep. Black test wire

5. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Step 3 Test the bumper and limit switches by connecting the test probes to black and white wire connections on the plugs as shown. Operate the switches. If they are good, you will hear a beep tone.

6. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Continuity test and batteries Continuity tests cannot be performed on batteries. It won’t harm the meter, but readings will not be correct. Power to the circuit or device being tested must be turned off or batteries should be removed while in the continuity mode. Other continuity tests Test other types of switches, wires, cables and incandescent lamps (flashlight bulbs etc) to gain experience with continuity testing, which will enhance troubleshooting skills.

7. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Review Plug the test leads in properly, red into red, black into black Check the selector setting; this is the setting for testing continuity Observe proper polarity when testing

8. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Multimeters Testing for DC voltage

9. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. DC Voltage Testing DC voltage testing as applied to cells and batteries is something that every student, regardless of experience, must know how to perform. No matter how simple or sophisticated an electronic device might be, weak or dead batteries can render it useless. Experienced technicians know that good troubleshooting techniques begin at the power source.

10. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Step 1 Insert the red test lead (wire) into the red jack. Insert the black test lead into the black jack

11. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Step 2 Rotate the selector switch to DC volts

12. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Step 3 Touch the test probes to the ends of a AA battery (cell), observing polarity. What is the voltage reading on the digital display?

13. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Step 4 Test the 7.2 volt hobby battery by touching the probe tips to the connectors inside of the plug. What is the reading on the digital display?

14. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Step 5 Remove the cells from the RC transmitter. Lay them out end to end, positive to negative etc. Connect the meter as shown. What is the total voltage of the 8 cells?

15. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Step 6 Place the cells back into the transmitter. Read the total voltage by placing the probes as shown (fig 1.) Continue to test. Observe the voltage readings as you move the black test probe. (fig 1.)(fig 2.) (fig 3.)

16. Copyright Carnegie Mellon Robotics Academy all rights reserved Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc. Review Plug the test leads in properly, red into red, black into black Check the selector setting, this is the setting for DC volts Observe proper polarity when testing