Hardware + Network Troubleshooting | Concepts Flashcards
The term methodology means:
a collection of systematic approaches to solving the technical problems we encounter
The 6-Step Troubleshooting Methodology is:
- Identify the problem
- Establish a theory of probable cause (question the obvious)
- Test the theory to determine the cause
- Establish a plan of action to resolve the problem and implement the solution
- Verify full system functionality and, if applicable, implement preventive measures
- Document findings, actions, and outcomes
In the Identify the problem step of troubleshooting:
question the user and identify user changes to the computer and perform backups before making further changes
Inquire regarding environmental or infrastructure changes that may have occurred
Review system application logs for clues to possible system errors
In the Establish a theory of probable cause step of troubleshooting, if necessary:
conduct external or internal research based on symptoms
In the Test the theory to determine the cause step of troubleshooting:
Once the theory is confirmed, determine the next steps to resolve the problem
If the theory is not confirmed, establish a new theory or escalate the issue
Typical causes for unexpected shutdowns include:
Dead short caused by loose screw, slot covers, or cards
CPU overheating
Power supply overheating
Power supply failure
What should you do if a dead short is caused by loose screws, slot covers, or cards?
Shut down the system and secure all metal components
What should you do if the CPU is overheating?
Check fan speed for CPU heat sink
Clean fan if it is dirty
Replace fan if it has failed or is turning too slowly
Check power management settings and CPU drivers in the OS to make sure that thermal throttling is working
What should you do if the power supply is overheating?
Check the power supply fan and clean it if possible
Replace the power supply with a higher wattage-rated unit if problem persists
What should you do if the power supply fails?
Test the power supply to verify proper operation
System lockups are typically caused by:
the corruption of memory contents
Follow these steps to diagnose system lockups:
- Shut down the system, remove and reinstall memory, and remove dust from the modules, the sockets, cooling vents, and fans
- Check the specifications for memory; the memory installed might not be the correct type for the motherboard and processor
- If memory has been overclocked, reset the memory to factory specifications by using the Auto or SPD options in the system BIOS setup
- Add additional system cooling
Overclocking is when you:
run the processor or memory at speeds faster than those recommended
Overclocking can cause:
components to overheat and the system to crash
If your system crashes after overclocking:
return the settings to the standard values and restart the system
POST code beeps are used by:
many BIOS versions to indicate either fatal or serious errors
Memory Problems; Video Problems; Processor or Motherboard Problems Beep Codes
Phoenix BIOS
1-3-4-1 or 1-3-4-3 or 1-4-1-1; None; 1-2-2-3
Memory Problems; Video Problems; Processor or Motherboard Problems Beep Codes
Award BIOS
Beeping (other than 2 long, 1 short); 2 long, 1 short; High-frequency beeps or Repeating high/low beeps
Memory Problems; Video Problems; Processor or Motherboard Problems Beep Codes
AMI BIOS
1 or 3 or 11 beeps, (1 long, 3 short beeps); 8 beeps, (1 long, 8 short beeps); 5 or 9 beeps
Memory Problems; Video Problems; Processor or Motherboard Problems Beep Codes
IBM BIOS
None; 1 long, 3 short beeps, or 1 beep; 1 long, 1 short beep
a blank screen non bootup can be caused by a variety of video configurations or cabling problems, some of which are:
If you have only one display, plugging the video cable into an inactive video port on a system
If a display with two or more inputs is not configured to use the correct cable
If a DVI or VGA cable is not tightly attached to the video port or display
If an HDMI, miniHDMI, DisplayPort, or miniDisplayPort cable is not completely plugged into the video port or display, the screen might be blank
If input cables and display input settings check out but the screen is still blank, shine a flashlight on the screen to see if any text or graphics are visible
Problems with BIOS time and setting resets are typically caused by:
problems with either the CMOS battery on the motherboard or the CMOS chip
The CMOS chip is a:
surface-mounted chip that cannot be replaced, so if it is bad, the motherboard must be replaced
The CMOS contents can be cleared by using what on the motherboard?
a jumper
Depending on the motherboard, the jumper might be labeled:
JBAT
CLRTC
CLR-CMOS
If a nonbootable drive is in the boot sequence:
the system will not start
Continuous reboots can be caused by problems with the power supply or by a Windows or other OS configuration. Some examples are:
Power Good voltage is too high or too low
Windows configuration setting for dealing with STOP errors (BSOD)
To leave a STOP error message onscreen until you decide to restart the system:
clear the Automatically Restart check box in the System Failure setting in the Startup and Recovery section of Advanced System Properties
Use a multimeter or a power supply tester to determine if:
a power supply has failed
If the power lead is plugged in to the wrong pins on the motherboard or has been disconnected from the motherboard:
the system will not start and you will not see an error message
To determine the correct pinout and installation check:
the markings on the front panel connectors, the motherboard, or the motherboard/system manual
Overheated power supplies can cause:
system failure and possible component damage
Overheated power supplies can be due to any of the following causes:
Overloading
Fan failure
Inadequate airflow outside or inside the system
Dirt and dust
An overloaded power supply is caused by:
connecting devices that draw more power (in watts) than the power supply is designed to handle
Consider upgrading the hard drive when you:
add more card-based devices to expansion slots
use more bus-powered USB and Thunderbolt devices
install more internal drives in a system
If you determine you should replace the power supply, purchase:
a unit that has a higher wattage rating and a higher +12 rating
If the fans fail what is at risk of damage?
The power supply and the entire computer
A fan that stops immediately after the power comes on usually indicates:
incorrect input voltage or a short circuit
To determine whether a fan has failed:
listen to the unit; it should make less noise if the fan has failed
If the fan blades aren’t turning or if they are turning very slowly:
the fan has failed or is too clogged with dust to operate correctly
To determine whether case fans have failed:
look at them through the front or rear of the system
or if they are connected to the motherboard, use the system monitoring feature in the system BIOS to check fan speed
The power supply’s capability to cool the system depends in part on:
free airflow space outside the system
You can do the following to improve airflow inside a computer:
Use cable ties to secure excess ribbon cable and power connectors out of the way of the fans and the power supply
Replace any missing slot covers
Make sure that case fans and CPU fans are working correctly
With the negative pressure technique:
the power supply fan works like a weak vacuum cleaner, pulling air through vents in the case, past the components, and out through the fan
When you open a system for any kind of maintenance, look for the following:
Dirt, dust, hair, and gunk clogging the case vents
A thin layer of dust on the motherboard and expansion slots
Dirt and dust on the power supply vent and fans
If using compressed air, be sure to:
spread newspapers around the system to catch the dirt and dust
If an overheating system has failed fans or empty fan bays, replace the failed fans or add new ones. To replace a fan follow these steps:
- After removing all power to the system and opening the case, locate any failed fans
- Disconnect the fan from the motherboard or the power supply
- Remove the fan from the case
- If you need to add a fan, determine the size of the fan needed and hold the fan inside the case as you attach screws to the fan from the outside
- Connect the fan to the system fan header on the motherboard
Intermittent failures of USB bus-powered devices usually happen because:
these devices draw power from the system’s power supply via the USB port
Intermittent failures of other USB external or of internal devices can be caused by:
damaged data cables
power supplies or connectors
ports
To troubleshoot device failures these problems:
- Shut down the device (and the computer, if the device is internal) and replace the data cable with a known-working replacement
- Turn on the device or computer
- Test the device over time
- If Step 1-3 didn’t resolve the problem, use the original data cable and try plugging it into a different internal or external port. Repeat Steps 2-3
- Try Steps 1-4 again, but this time use a replacement power connecter or AC adapter
- When you find the defective component, the problem stops
A fan connected directly to a power supply will run as soon as the system is turned on, but if a fan spins and a computer never displays any startup messages, this could indicate a variety of problems. Check the following:
Make sure the main ATX and 12V ATX or EPS power leads are securely connected to the appropriate sockets
Make sure the CPU and memory modules are securely installed in the appropriate sockets
Indicator lights on the front or top of most desktop computers display:
power and hard drive activity
If you can see smoke or smell a burning odor with a chemical overtone coming from the power supply’s outside vent what has happened?
Your power supply has died
or failing capacitors
When a power supply blows up like this, it can:
also destroy the motherboard, bus-powered USB devices connected to the computer, and other components
The capacitors are:
cylindrical components near the CPU socket on the motherboard or inside the power supply
Power supplies have a:
built-in safety feature that shuts down the unit immediately in case of short circuit
The following steps are designed to determine whether a power problem is caused by a short circuit or another problem:
- Smell the power supply’s outside vent
- Check the AC power to the system; a loose or disconnected power cord, a disconnected surge protector, a surge protector that has been turned off, or a dead AC wall socket will prevent a system from receiving power
- Check the AC voltage switch on the power supply; it should be set to 115V for North America. If the switch is set to 230V, turn off the power, reset the switch, and restart the system
- If the system is older and uses a PS/2 mouse or keyboard, check the connectors; a loose keyboard connector could cause a short circuit
- Turn off the system, disconnect power and open the system. Verify that the power leads are properly connected to the motherboard.
- Check for loose screws or other components, such as loose slot covers, modem speakers, or other metal items that can cause short circuit.
- Remove all expansion cards and disconnect power to all drives; restart the system and use a power supply tester or a multimeter to test power to the motherboard
- If the power tests within accepted limits with all peripherals disconnected, reinstall one card at a time and check the power
- If a defective card or drive has a dead short, reattaching the defective card or drive should stop the system immediately upon power-up
- Check the Power Good line at the power supply motherboard connector with a multimeter or a power supply tester
Capacitors are used as part of:
the voltage stepdown circuits that provide power to the processor
Examples of crash screens are
Windows STOP error (BSOD)
macOS pin wheel
Crash screens are caused by:
OS, application, or hardware errors
STOP errors (BSOD) can be caused by any of the following:
Incompatible or defective hardware or software (start the system in Safe mode and uninstall the last hardware or software installed)
Registry problems (System Restore can also be used to revert the system and registry to an earlier state)
Viruses
Miscellaneous causes (Check the Windows Event Viewer and check the System log)
The STOP error (BSOD) is listed by:
name and number
To determine the exact cause of a STOP error (BSOD):
note the number or name of the error and look it up at the Microsoft support website
The solution to STOP errors (BSOD) might involve one or more of the following changes to your system:
Changing the system registry, back the registry first!
Removing a newly added component
Replacing components such as memory
Upgrading an application
Downloading and installing a hotfix for your OS
The official name for the macOS pin wheel is:
the spinning wait cursor
the macOS pin wheel appears most often when:
an application or macOS itself has become unresponsive
The following are some causes of macOS responsive:
Lack of system RAM
Less than 10 percent free space on the macOS system drive
Damaged application (Run Disk Utility using the Verify Disk Permissions option)
The following are some solutions for macOS unresponsiveness:
Use the Force Quit command to terminate an application that won’t respond
If a particular application causes unresponsiveness, open the ~Library/Preferences folder, find the .plist file for the app, and drag it to the trash
Use Activity Monitor to view CPU, memory, energy, disk, and networking performance stats
Upgrade to the latest macOS version and keep it updated
A forced restart is performed by pressing and holding the Cmd+Ctrl buttons while pressing the power button
Logs on a device are:
records kept to track the history of what has happened on the device
Logs on a device record:
the tasks the computer has performed
the people who have logged in or out
the applications opened, and so on
To access logs and error messages, go to:
Control Panel> Administrative Tools> Event Viewer
To diagnose problems with motherboards, RAM, CPUs, and power, use the following tools:
Multimeter
Power supply tester
Loopback plugs
POST card/USB
Multimeters are designed to perform many different types of electrical tests, including the following:
DC voltage and polarity
AC voltage and polarity
Resistance (ohms)
Diodes
Continuity
Amperage
Digital multimeters are using:
autoranging, which means they automatically adjust to the correct range for the test selected and the voltage present
Analog multimeters must be set:
manually to the correct range and can be damaged more easily by overvoltage
Multimeter setting; Probe Positions; Procedure
AC voltage (Wall outlet)
AC; Red to hot, black to ground; Read voltage from meter, should be near 110V-120V in North America
Multimeter setting; Probe Positions; Procedure
DC voltage (power supply outputs to motherboard, drives, batteries)
DC; Red to hot, black to ground; Read voltage from meter, compare to default values
Multimeter setting; Probe Positions; Procedure
Continuity (cables, fuses)
CONT; Red to lead at one end of able, Black to corresponding lead at other end; No CONT signal indicates bad cable or bad fuse
Multimeter setting; Probe Positions; Procedure
Resistance (ohms)
Ohms; Connect one lead to each end of resistor; Check reading, compare rating for resistor
Multimeter setting; Probe Positions; Procedure
Amperage (ammeter)
Ammeter; Red probe to positive lead of circuit, black lead to negative lead running through component to be tested; Check reading, compare to rating for component tested
Both 20-pin and 24-pin (ATX) power connector are designed to:
be back-probed, so you can run the red probe through the top of the power connector to take a reading
You can use a power supply tester to determine:
if a power supply is working. (the power supply does not need to be removed from the computer for testing, but needs to be plugged into a working AC outlet or surge suppressor)
There are two types of power supply testers:
a simple go/no-go tester (if there is power on the power supply a green LED turns on)
one that has its own power switch and checks the major voltage levels, when you turn it on
Read/write failures can take place for a number of reasons, including the following:
Physical damage to the drive
Damaged cables
Damaged SATA host adapter on motherboard
Overheated hard disk
Overheated CPU or chipset
To prevent overheating of the hard disk:
install a cooling fan in front of the 3.5-inch drive bays used for a hard disk(s) and make sure it pulls air into the PC
To improve slow performance with SATA hard disks, look for these problems:
Reduced-performance with SATA hard disks, look for these problems
Using a 3Gbps cable with a 6Gbps drive and host adapter
SATA host adapter configured for IDE or emulation mode
SATA host adapter configured to run at reduced speed
To improve slow performance with SSDs, look for the following issues:
Connecting the drive to a slow SATA host adapter
The partition may be misaligned
The TRIM command is not enabled for the drive
Not optimizing the OS for use with SSDs
Misaligned partitions cause:
slow read/write/reallocate performance
Loud noises coming from a drive can have at least two causes:
A loud clicking noise is typically caused by repeated rereads of defective disk surfaces by the hard disk drive heads (Replace the hard disk immediately after making a backup copy)
Humming noises can be caused by rapid head movement on a normally functioning hard disk
The boot drive is almost always:
the primary hard drive
Failure to boot can be caused by the following reasons:
Boot sequence does not specify system hard disk, or lists system hard disk after other drives with nonbootable media
CMOS settings have been corrupted and system cannot find a bootable drive
The boot configuration data (BCD) store used by Windows to control disk booting has been corrupted
A drive not recognized issues can involve problems with cabling, power, BIOS settings, or hard disk failure. If the hard disk is running, check the following:
Bus-powered USB hard disk not recognized
USB or Thunderbolt drive not recognized
SATA Hard Disk or SSD drive not recognized
An OS not found error during boot can be caused by:
Nonbootable disk in USB Drive
Boot sequence doesn’t list hard disk
Incorrect installation of another operating system
RAID not found problems can result from the following:
RAID function disabled in system BIOS (Reconfigure SATA ports used for RAID as RAID and restart the system)
Power or data cables to RAID drives disconnected (Reconnect cables to RAID drive(s) and restart the system
If RAID function is disabled in system BIOS do this:
Reconfigure SATA ports used for RAID as RAID and restart the system