Download Multimeters - Robotics Academy

Multimeters
Testing for continuity
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
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.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
Step 1
Move the selector
switch to the continuity
setting.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
Step 2
Black
test wire
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.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
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.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
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.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
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
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
Multimeters
Testing for DC voltage
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
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.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
Step 1
Insert the red test lead
(wire) into the red jack.
Insert the black test
lead into the black jack
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
Step 2
Rotate the selector
switch to DC volts
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
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?
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
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?
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
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?
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
Step 6
(fig 1.)
(fig 3.)
(fig 2.)
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.
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved
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
Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Copyright Carnegie Mellon Robotics Academy all rights reserved