Electrical Troubleshooting

1
Electrical Troubleshooting

• Multimeter Techniques

2
Multimeter Familiarization

• All multimeters perform many of the same
  functions, but may look different.
• This digital multimeter (DMM) is very similar to
  those you will use in lab.
• Lets have a look.

3
Multimeter Familiarization

• This DMM can measure
• DC Volts
• AC Volts
• DC Amps
• Resistance (Ohms)
• Continuity w/ alarm
• Diodes
• What do each of these mean?

4
Volts - Amps - Resistance

• Volts -
• A measure of electrical pressure.
• Very similar to water pressure. (psi)
• Amperes - (Amps)
• A measure of electrical current flow.
• Very similar to water flow. (gpm)
• Resistance - (Ohms)
• Resistance to flow of electrons
• Very similar to friction loss in water systems.

5
Ohms Law
E Volts I Amperes R Resistance (Ohms)
Volts (E) Amperes (I) x Ohms (R) Amperes (I)
Volts (E) / Ohms (R) Ohms (R) Volts (E) /
Amperes (I)
6
DC Volts

• Direct Current Voltage
• Current flows one direction
• Ex. Current created by a battery.
• Meter is in parallel to the circuit.
• Selecting the correct scale.
• Selecting the correct terminal.

7
AC Voltage

• Alternating Current Voltage
• Current flows from positive to negative
• Ex. Current in a house.
• Meter is in parallel to the circuit.
• Selecting the correct scale.
• Selecting the correct terminal.

8
Resistance (Ohms)

• Ohms
• How much resistance is there to current flow?
• Is there a poor connection or no connection?
• High resistance
• Current MUST NOT be present.
• Make sure the juice is off!
• Selecting the correct scale.
• Selecting the correct terminal.

9
Continuity Alarm

• Continuity
• Very closely related to resistance.
• Only measures if there is a connection.
• Does not measure the degree to which a connection
  is made or the amount of resistance that exists.
• Alarm sounds if continuity exists.

10
DC Amperes

• Direct Current Amperage
• DO NOT use with AC!
• DO NOT use over rated amperage in DC!
• Used in Series with a circuit.
• This means all current in the circuit must travel
  through the meter!
• Selecting the correct scale.
• Selecting the correct terminal.

11
QUESTIONS