Quiz # 1



Exercise # 1

Introduction to Computer

Using a Multimeter

Objective:

• Identify the external and internal components of the computer

• Learn and follow the safety procedures in the Lab

• Use a multimeter to measure DC / AC voltages

• Use a multimeter to measure resistance

• Use a multimeter to perform continuity check

Setup:

For this lab you will need the following:

• A working computer

• A digital multimeter with leads

• An IDE cable

• Philips screw driver

• Antistatic wrist strap

• Long-nose pliers

• Small container for the screws

• Small flash light

• Paper and pen

Safety issues:

▪ Use the antistatic wrist strap to avoid having Electro Static Discharge (ESD). (Warning: you should not wear the antistatic wrist strap when working with a monitor).

▪ Do not work with computers while they are on. You might get electrocuted or you might unintentionally damage some components.

▪ Some elements in the computer case or inside the printer might get extremely hot. Give them time to cool and make sure not to touch them if the computer was on immediately after turning it off.

▪ It is not recommended that you try and fix a monitor. Leave this to more experienced professionals.

▪ Do not leave your workplace unattended. Do not loose any of the components you are working with.

▪ Carefully inspect the components you are about to remove so you know how to put them back again.

▪ Do not leave your desk until you make sure everything is well organized.

▪ When inserting cables into their respective sockets don’t force them if they are not fitting. This will bend the pins.

Exercises:

Identifying the computer’s external elements

▪ Case, monitor, keyboard, mouse, cables, speakers, and so on.

▪ Switches: on and off (ATX type), reset, and the switch on the power supply.

▪ Ports: they provide connections to external peripheral devices. Power, Mouse and keyboard (PS/2) port, video display, serial, parallel, Universal Serial Bus (USB), Firewire, Game port, Modem, Ethernet network, speaker, line in, and microphone.

▪ Drive bays and drives such as the 3.5” disk drive and the CD ROM.

▪ LEDs: Power LED, HD LED

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Connect the different cables to the ports and turn on the computer. Check if everything is working correctly.

Does the monitor display a picture? _____

Does the pointer move when you move the mouse? _____

Does the keyboard work? _____

Does the speaker produce sound? _____

Questions:

1. How do you reset the computer? When would you resort to resetting it?

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2. How do you turn off the computer if it crashed and it was completely unresponsive?

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3. When you turn off the computer and it was still plugged in, does that mean that the computer is completely powered off?

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4. How do you know that the hard drive is working?

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5. Name and draw the symbol of the parallel port and PS/mouse?

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Identifying the computer’s internal elements

After making sure the computer is turned off and unplugged, open the computer case and inspect the following components.

• Motherboard

• RAM

• BIOS

• CMOS Battery

• Chipset

• Power Supply

• Expansion Slots

• Hard Disk drive

• Fans

• Heat Sinks

• Display card

• Internal connectors and cables

Questions:

1. What is the name of the manufacturer on the BIOS?

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2. Look at the different cables inside the case, What are they connected to?

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3. What are the different expansion slots available? How many for each?

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4. What is the power rating of the power supply?

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5. How many RAM slots are available on the motherboard?

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Using the multimeter:

A multimeter is an invaluable tool when it comes to ensuring that the correct voltages are being passed to a device or computer. It helps you determine whether the problems you may be experiencing are a result of a faulty power or a faulty device. If the proper voltages are not being delivered the device cannot function properly.

You can also use the multimeter to check the continuity on cables. A continuity check gives you a quick indication of whether a wire is broken. If you get a reading of 0 ohms, the wire is good. If the reading is infinite, there is a break in the cable.

Measuring DC Voltage:

1. Prepare the multimeter for use. If the multimeter has detachable leads, connect the black lead to the negative jack and the red lead to the positive jack on the multimeter. Set the multimeter to measure DC or AC depending on the type of the measured voltage. Set the meter to the highest voltage rate to prevent the multimeter.

2. Turn off the computer and unplug it.

3. Remove the system cover and locate the molex power connector which is large, round-pin type connector with 4 Pins used for some drives like HDD.

4. Connect the black multimeter lead to one of the black wires and the red multimeter to the yellow wires.

5. Plug in the computer and turn on the power. Observe the voltage reading and record it.

Voltage level: _________

AC/ DC: ________

6. Measure the Power supply input voltage

Input Voltage level: _______________________

Is it AC or DC? ______________

7. Measure the Power supply output voltage

Output Voltage level: __________

Is it AC or DC? ____________

8. Measure the red wire voltage of Berg connector

Voltage level: ________

AC/ DC: ________

9. Measure the resistance of IDE cable

Resistance Value: __________

Measuring Continuity:

1. Remove the IDE cable from your computer or ask your instructor to give you one.

2. Change the setting of the multimeter to read Ohms.

3. Place one lead on one end of pin1 and the other end of pin 1. Record the reading.

Pin 1 reading:

Do you hear beeps?

4. Check the Power cord continuity

Once you are done, shutdown windows. When the computer is turned off unplug all cables, starting with the power cord, and then place everything neatly on the table.

Questions:

1. What is the voltage of the red wire of molex connector?

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2. What is the hazard of power sags or other variations in frequency?

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3. What is power surge and power sag?

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4. What is a solution to power surges and sags?

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PS/2 Mouse

PS/2 Keyboard

USB

RJ45 LAN

Parallel Port

Game Port

Serial Port (COM 1)

Serial Port (COM 2)

Line Out Audio

Line In Audio

Microphone

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