1.3 Identify tools, diagnostic procedures and troubleshooting techniques for personal computer components Part 3

> Display Device Troubleshooting

CRT Monitor Troubleshooting

No power:

• Make sure power button (or switch) is ON.
• Make sure A/C power cord is securely connected to the back of the monitor and to a power outlet.
• Plug another electrical device into the power outlet to verify that the outlet is supplying proper voltage.

Power is ON but no screen image:

• Make sure the video cable supplied with the monitor is tightly secured to the video output port on the back of the computer. If the other end of the video cable is not attached permanently to the monitor, tightly secure it to the monitor.
• Adjust brightness and contrast.
• Verify whether an adapter is required for proper signal continuity between graphics card and monitor.

Flickering:

• Not enough power supplied. Connect the monitor to a different outlet. If using a surge protector, reduce the number of devices plugged in.
• Check the refresh rate (vertical frequency) is set correctly for that specific monitor.
• Remove any devices from the area around the monitor that emit magnetic fields such as radios, surge protectors, unshielded speakers, fluorescent lights, AC power converters, desk fans, etc.
• Make sure the graphics card in your computer can use non-interlaced mode at the desired frequencies. To enable your graphics card to support higher refresh rates, try selecting fewer colors or running lower resolutions.

Wrong or abnormal colors:

• If any colors (red, green, or blue) are missing, check the video cable to make sure it is securely connected. Loose or broken pins in the cable connector could cause an improper connection.
• Connect the monitor to another computer.
• Select Degauss from the Monitors Menu. Do this only once.

Screen image rolls vertically:

• Make sure video input signals are within the monitor's specified frequency range.
• Try the monitor with another power source, graphics card, or computer system.
• Connect the video cable securely.

LCD Monitor Troubleshooting

No power:

• Make sure power button (or switch) is ON.
• Make sure A/C power cord is securely connected to the back of the monitor and to a power outlet.
• Plug another electrical device into the power outlet to verify that the outlet is supplying proper voltage.

Power is ON but no screen image:

• Make sure the video cable supplied with the LCD display is tightly secured to the video output port on the back of the computer. If the other end of the video cable is not attached permanently to the LCD display, tightly secure it to the LCD display.
• Adjust brightness and contrast.

Wrong or abnormal colors:

• If any colors (red, green, or blue) are missing, check the video cable to make sure it is securely connected. Loose or broken pins in the cable connector could cause an improper connection.
• Connect the LCD display to another computer.

> Adapter Card Troubleshooting

“Optional XXXX Optional ROM Bad, Checksum=YYYY” error message. (ROM chip on an expansion card is having problems.)

• Remove one card at a time until you can isolate which card is causing the conflict.
• Check to see if you have a memory address conflict with another card, especially if you just installed another device recently.
• Replace the expansion card with the faulty ROM chip.

Modems:

No dial tone for modem:

• If it is a modem built into the motherboard, check the CMOS setup program to ensure that the modem is enabled.
• Ensure that the appropriate drivers are loaded and working correctly.
• If it is an external modem, make sure the modem has power and is connected properly to the PC.
• Check that the phone line is active.
• Replace the phone cable.
• Replace the modem.

Receive an error message such as “Could not open port.”:

• Check for resource conflicts such as I/O addresses and IRQs.
• A program is loading in the Windows Startup folder that opens a COM port for some other use other than the modem.
• Try rebooting to see if the port was opened by another program. Rebooting may correct the problem.

PC or communication software refuses to recognize the modem.

• If it is an external modem, make sure the modem has power and it is turned on. In addition, make sure the cables are connected to the serial port.
• If it is an internal modem, make sure the modem is seated properly in the slot.
• Check in the BIOS setup program that the modem and/or serial port is enabled.
• Check for resource conflicts such as I/O addresses and IRQs.
• Try the modem in another system.
• Try the modem in another system.
• Replace the modem.

Sound Problems:

Speakers do not produce any sound

• Check the volume control in Windows and the volume control in the application to see if the sound has been muted or has been adjusted low.
• Check the volume control on speakers.
• Make sure the speakers are turned on and have power.
• Check the speaker cable is installed into the correct port on the back of the sound card.
• Check that the sound drivers are installed and functioning properly.
• Swap the speaker cables and power cable one at a time.

No audio when playing an Audio CD

• Check the volume control (specifically Master Volume and CD Player) in Windows and the volume control in the application to see if the sound has been muted or low.
• Check the volume control on speakers.
• Make sure the speakers are turned on and have power.
• Check to see if the four-wire CD audio cable is connected between the CD drive and the sound card.

When trying to play a high-quality audio file through a USB speaker system, you get an error message saying “Out of bandwidth”

• Disconnect extraneous USB devices such as joysticks, scanners, and others.
• Purchase an additional USB controller and attach the speakers to it so that they can have sole access to all of its bandwidth.
• Play the audio file at a lower playback quality or use a lower-quality version of the file.

When an expansion card is inserted into a system, it must be configured to use the proper resources. The resources include I/O addresses (including COMx/LTPx), IRQs, DMAs and Memory addresses. When configuring a card, one general rule should apply. No two devices can use the same resource. Therefore, two expansion cards should not be set to use the same DMA channel or the same I/O address. If two devices are using the same setting, the devices will not work properly or not work at all.

To determine what the available resources are, use utilities, which come with the operating system such as Windows Device Manager located within the control panel.

Access Device Manager Under Windows 2000 / XP

There are two different methods that can be used to access the device Manager under Windows XP:

• Click the START button on the Windows taskbar.
• Select CONTROL PANEL from the menu.
• Select PERFORMANCE AND MAINTENANCE.
• Select SHOW BASIC INFORMATION ABOUT YOUR COMPUTER.
• Select the HARDWARE tab.
• Click on the DEVICE MANAGER button.

After determining which resources the card can use, the card itself can be configured one of several ways:

• DIP switches and/or Jumpers
• A software setup program
• Using Plug and Play (PnP)

Normally, the BIOS assigns unique IRQs to PCI devices. If your system supports PCI IRQ Steering, and it is enabled, the BIOS will assign the IRQs to the PCI devices and Windows will typically only change the IRQ settings if it detects a conflict. If there are free IRQs to go around, IRQ Steering allows Windows to assign multiple PCI devices to a single IRQ, thus enabling all the devices in the system to function properly.

Trouble Shooting Input Devices

Keyboards

Keyboard fails to be recognized during boot up or the keyboard is completely dead and no keys appear to function.

• Swap the keyboard, reboot the system when a keyboard is replaced.
• Use a multimeter to check the +5 V supply at the keyboard connector.
• Check to see if the motherboard has a fuse to protect the +5 V supply feeding the keyboard connector.

> Recognize the names, purposes, characteristics and appropriate application of tools for example:

BIOS, self-test, hard drive self-test and software diagnostics test

Power-on self-test (POST) is the common term for a computer's pre-boot sequence. The same basic sequence is present on all computer architectures. It is the first step of the more general process called initial program load (IPL), booting, or bootstrapping.

Duties of the main BIOS during POST are as follows:

• verify the integrity of the BIOS code itself
• determine the reason POST is being executed
• find, size, and verify system main memory
• discover, initialize, and catalog all system buses and devices
• pass control to other specialized BIOSes (if and when required)
• provide a user interface for systems configuration
• identify, organize, and select which devices are available for booting
• construct whatever system environment that is required by the target OS

The BIOS will begin its POST duties when the CPU is reset. The first memory location the CPU tries to execute is known as the reset vector. In the case of a hard reboot, the northbridge will direct this code fetch (request) to the BIOS located on the system flash memory. For a warm boot, the BIOS will be located in the proper place in RAM and the northbridge will direct the reset vector call to the RAM.

During the POST flow of a contemporary BIOS, one of the first things a BIOS should do is determine the reason it is executing. For a cold boot, for example, it may need to execute all of its functionality. If, however, the system supports power savings or quick boot methods, the BIOS may be able to circumvent the standard POST device discovery, and simply program the devices from a preloaded system device table.

The POST flow for the PC has developed from a very simple, straightforward process to one that is complex and convoluted. During POST, the BIOS must integrate a plethora of competing, evolving, and even mutually exclusive standards and initiatives for the matrix of hardware and OSes the PC is expected to support. However, the average user still knows the POST and BIOS only through its simple visible memory test and setup screen.

The following POST beep codes were sometimes found on the CompTIA A+ Core Hardware Exam:

Click here for more POST Beep Codes

S.M.A.R.T. stands for Self-Monitoring Analysis and Reporting Technology. S.M.A.R.T. is reliability prediction technology for both ATA/IDE and SCSI environments. Pioneered by Compaq, S.M.A.R.T. is under continued development by the top five disc drive manufacturers in the world: Seagate Technology Inc., IBM, Conner Peripherals Inc., Western Digital Corporation, and Quantum Corporation.