Download Probe Selection

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 is
Alternating 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
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Chapter 8 In Class Lab Assignment
CIT 1100
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.
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Chapter 8 In Class Lab Assignment
CIT 1100
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
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Chapter 8 In Class Lab Assignment
CIT 1100
To probe the connectors push the
probe in from the back until you hit
the metal clips. Be careful not to
accidentally touch anything else
with the metal part of the probe.
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:
Molex connectors
are used for hard
drives and most all
other peripherals.
The smaller Berg
connector is used
for the floppy
drive.
Connect your probe to any 12 V 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 the metal chassis of the system.
What are you measuring? _______________________________
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Chapter 8 In Class Lab Assignment
CIT 1100
Check the resistance
between the Ground Pin on
the power supply and the
chassis. Indicate the
measurement:________
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 cord
Step (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:
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Chapter 8 In Class Lab Assignment
CIT 1100
Parameter
Measured in BIOS Measurement
Temperature
Y/N
________
Voltages
Y/N
_______________________
Fan Speeds
Y/N
_________
If supported where in BIOS Setup did you locate the measurements? _______
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Chapter 8 In Class Lab Assignment
CIT 1100
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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