Chapter 8 In Class Lab Assignment

CIT 1100

This lab introduces the use of a Digital Voltmeter DVM. We will be using the Fluke 8010A to make measurements of various voltages.

The Meter is divided up into various areas. The 4 white push buttons make up the Function Select Area.

To make Voltage measurements you first decide if you want to measure AC, or DC, the select button is the first one on the left. Any voltage measurement inside the system is Direct Current, measurements outside the system such as the wall socket isAlternating Current AC.

to select DC, the first button should be in the out position

to measure AC push in the button

push in the V button to select Voltage

Range Select

After setting the voltage you next need to set the range of the meter. The meter will read anywhere from 0 to 200 mV. in the first range, from 0 to 2 Volts in the second range, from 0 to 20 Volts in the third range, from 0 to 200 in the forth range, and from 0 Volts to 2000* in the fifth range. * Note that in the fifth position the AC voltage is limited to 750 V.

For every voltage measurement inside a PC the 0 – 20 V. DC measurement will work best. If you select a range that is too small for your reading, the meter will only measure up to the maximum setting of the range. For example if you measure 12 V. DC and meter is set to 0 to 2 V. DC it won’t be accurate.

Probe Selection

Depending on the operation you wish to perform determines which probes you will be using. Since measuring current is probably something you would never need to do while troubleshooting a PC we will skip current measurement and focus on measuring Voltage and Resistance.

To measure Voltage AC/DC, or Resistance you need to connect your probes to the common jack (Black) and the voltage jack (Red), as shown in the diagram above. The common jack is normally connected to the system ground with an alligator clip connector for measuring DC. The red connector is the probe for measuring voltage.

To measure resistance use the common cable as well as the red connector marked V/kΏ/S. Remove the cover from your system while powered on and locate the motherboard power connection. Using your voltmeter confirm and record the Voltages below connect the Black to the PC case (Ground).

This shows both ATX power connectors, the newest 24 pin left, and the older 20 Pin Right

Locate the Berg connector supplying power to the floppy drive and measure the voltages for the yellow and red cables.

Locate the Molex connector supplying power to the hard drive and measure the same voltages.

RECORD THE MEASUREMENTS ON THE LINES BELOW:

Connect your probe to any 12V dc source and set your voltmeter’s range to 2000 V dc. Note the reading, then set the range to 2V dc and notice the reading.

Which gave a more accurate measurement? ______

Measuring Continuity(Voltage is never on while measuring continuity)

Unplug the Power cord from the back of the power supply, and the wall outlet. Check the resistance from the ground connection on the power supply connector and themetal chassis of the system.

What are you measuring? ______

With the AC Line cord disconnected from the wall outlet:

  1. Set the voltmeter to read AC voltage, 200 V.
  2. UNPLUG LINE CORD FROM WALL OUTLET.(see diagram below)
  3. Insert the probes into the female end of the UNPLUGGED line cord.
  4. Plug the AC line cord into the outlet and measure the line voltage.
  5. Record the voltage ______V.A.C.
  6. Unplug the line cord then remove the probes.

Step (2) unplug both ends of AC cordStep (3) insert probes into female end

System BIOS Power/Temperature Monitoring –

Some System Bios supports monitoring system parameters such as temperature, voltages, as well as fan rotation speed. Power up your system, enter System Bios Setup and determine if your system supports monitoring any of the parameters listed below:

ParameterMeasured in BIOSMeasurement

TemperatureY/N______

VoltagesY/N______

Fan SpeedsY/N______

If supported where in BIOS Setup did you locate the measurements? ______

Name: ______Date : ______Lab #8

HAND IN ONLY THIS PAGE

(1-4) indicate the voltages for each color coded cable:

  1. Red_____
  2. Yellow_____
  3. Orange_____
  4. Black_____

5. When testing Continuity, the meter’s Function Select should be set to what

______

6. If you measure continuity from system ground to the power cord ground what would you expect to see?______

7.What is the difference in voltage measurements between a Molex connector’s Red Wire and a Berg Connector’s Red Wire? ______

8. What kind of power connector did your system use, a 20 pin or a 24 pin?

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