Chapter 5: Hardware and Network Troubleshooting

Power-On Self Test (POST)

A diagnostic test run by the computer’s BIOS to check major system components before booting the OS

Beep Codes

Audio signals by the BIOS during POST to indicate hardware issues

BIOS Configuration

Firmware settings are used to configure hardware parameters, boot devices, system time, and enable/disable system components

Blank Screen on Boot

A situation where no video output appears during startup, often caused by issues with video cards, RAM, CPU, or BIOS misconfigurations

BIOS Battery (CMOS Battery)

A battery on the motherboard that maintains BIOS settings and the system clock when the computer is powered off

Boot Order

The sequence of devices the BIOS attempts to boot from. An incorrect boot order can lead to startup errors or booting into the wrong devices

Blue Screen of Death (BSOD)

A criticial Windows error screen indicating a system crash

Safe Mode

A diagnostic boot mode in Windows that loads minimal drivers and services to troubleshoot issues

System restore

Windows recovery options that revert the system to the previous working state when encountering errors after changes

Hardware Diagnostic Tools

Tools provided by the hardware manufacturers to test system components for failures

Mutimeter

A diagnostic tool to measure electrical output used to test power supplies and circuits

Fans Spin but No POST

Indicates that while power reaches the fans, other components may not be receiving power

Disk Defragmentation

A process that reorganizes fragmented data on hard drives to improve read/write efficiency

Monitoring Software

Software or BIOS utilities used to monitor component temperatures, fan speeds, and voltages

Burning Smell / Smoke

A severely damaged processor or motherboard components

Random Shutdowns

Unexpected system shutdowns without warning, often due to overheating, failing hardware, or power issues

Event Viewer

A Windows tool that logs system events, errors, and warnings for diagnostic purposes

Device Manager

A Windows interface for managing and troubleshooting hardware devices and drivers

Reliability Monitor

A Windows tool that provides a visual timeline of system events and stability issues, including application crashes and hardware failures.

Clicking sound in a hard drive

Indicates a problem with the read-write head moving across the platter

Inaccurate System Date/Time

Typically caused by a failing motherboard battery (CMOS battery), leading to loss of BIOS settings on every reboot

Jumper Reset (BIOS Reset)

A method on older motherboards to reset BIOS settings by moving a physical jumper on the motherboard

Paper Jam

Occurs when a paper is stuck inside the printer path and prevents the printing process from continuing

Jitter

Measures variation in delay by sampling elapsed time between packet arrival and sending

Signal-to-Noise Ratio (SNR)

Measures the strength of a desired signal compared to unwanted background noise

Broken screen

• Back up data first

• Replace the screen (no easy fix)

• Sharp glass — use tape or a screen protector until repair

Improper charging

• Check cables and ports; remove debris

• Avoid damaged or frayed cables; test with known good cable

• Verify the power adapter (multimeter if needed)

Physically damaged ports

• Charging/data transfer issues

• Check for visible damage

• Often requires full system board replacement

Dim Image

A display that appears too dark due to low brightness/contrast settings. To fix this, use the onscreen display or buttons on monitors, TVs, or projectors to increase brightness and contrast

No Video After Windows Loads

Situation where the monitor works during POST but loses signal once the OS loads

Fuzzy Image

A blurry display resulting from mismatched video resolution settings. To fix this, increase the resolution that matches your monitor’s resolution

Burn-in

A persistent ghost image on displays caused by static images left on the screen for extended periods. To fix this, replace the device

Dead pixels

Non-functioning pixels that remain black on the screen. To fix this, you have to replace the device

Flashing Screen

A display that intermittently turns off/on, often due to a loose video cable connection, faulty cable, or incorrect display settings

Incorrect Color Display

Displaying colors inaccurately due to misconfigured monitor settings, OS color profiles, driver issues, or night light mode being active

Backlight Failure

A condition where part or all of the display is dim or dark due to failed backlighting

Slow Performance (Storage)

Noticeable system sluggishness often caused by constant disk LED activity due to disk errors, fragmentation, or failing hardware

Click of Death

A loud, repetitive clicking noise from a hard drive indicates mechanical failure, often followed by grinding or scraping sounds.

Boot Failure Symtoms

Indicators such as "Drive not recognized," "Boot Device Not Found," or "Operating system not found" errors occur during startup.

RAID Failure

When one or more drives in a RAID array fail, due to hardware malfunction, power issues, or communication errors

RAID Recovery

Process of restoring a RAID array after a failure. Requires careful identification of the issue; drives should not be removed haphazardly. Always check RAID console status first.

S.M.A.R.T (Self-Monitoring, Analysis, and Reporting Technology)

A system integrated into storage drives that monitors drive health and predicts failures through diagnostic metrics

S.M.A.R.T. Analysis

Continuous monitoring of drive health metrics over time to detect early warning signs of drive degradation, often includes automated alerts

Input/Output Operations Per Second (IOPS)

A performance metric that measures how many read/write operations a storage device can perform per second

Extended read/write time

Performance degradation during data access due to bottlenecks in memory, bus communication, or physical drive access

Array Missing (RAID Controller Failure)

Entire RAID volume is missing due to a failed or disconnected RAID controller, leading to inaccessible RAID arrays

QoS (Quality of Service)

Using a network protocol to prioritize certain traffic types over other

No boot device available

1. Go into UEFI or BIOS to check boot order

2. Check if storage devices are recognized in UEFI or BIOS

Operating system not found

This would indicate that the hard drive was recognized but that the Windows OS was not installed properly

Screen flickering

Often caused by a failing backlight that needs to be replaced 

Duplicate MAC address

This occurs when two or more devices are responding to data requests as if they are the only device on the network with that physical address

Single beep after POST

Indication the successful completion of the POST

White streak on a printed image

Clean the printer’s corona wires

6 steps of troubleshooting

• Identify the problem

• Establish a theory

• Test the theory

• Establish a plan of action

• Verify system functionality

• Documentation

Power button is not connected properly to the motherboard

Follow the wires from the power supply to the motherboard to verify that it is connected properly

Wall outlet is faulty

Use a multimeter or voltmeter to test the power outlet

Power cable to the computer is faulty

Disconnect the power cable and test it with the multimeter

Power supply is faulty

Take it out and replace it with a new power supply

Power cables from power supply to components are faulty

Test all of the cables with a multimeter and make sure to check each pin on each side of the cable

Incorrect voltage setting on power supply unit

Make sure to select the right voltage setting based on the area of the world (US: 120, EU: 220-240)

Failure of a single disk in a RAID

If you’re using RAID 1 or 5 then you won’t suffer any data loss because they have redundancy

Missing pins on VGA port/cable

This will lead to display failure, incorrect colors, or resolution/sync issues

Port Flapping

Caused by an intermittent connectivity issue between the client and the network switch

Full duplex

Network that sends or receives information at the same time

Voice over Internet Protocol (VoIP)

Set of protocols that are used to send streaming voice and video in real time

Latency

Time it takes for a signal to reach the intended client

3 steps to fix a frozen print queue

1. Clearing the queue

2. Restarting the spooler

3. Updating drivers

Grinding noises in an inkjet/impact printers

Usually related to the cartridge mechanism

Grinding noises in a laser printer

Usually related to the toner cartridge, fuser, or rollers

Paper not feeding

Often caused by worn pickup rollers

Multi-page misfeed

Occurs when multiple sheets of paper are pulled into the printer at once

Printer fails to recognize the paper tray

Happens for a variety of reasons, and when the tray isn’t detected, the printer won’t be able to pick up paper to begin the printing process

Faded printouts

For most printers, check if the ink, ribbon, or toner
For impact printer, it’s the result of either a worn ribbon or an improper gap between the printhead and the paper

Blank page

Can be a result of a software issue where the computer mistakenly sends a blank page to the printer

White stripes

Common defect in laser printers, usually linked to a dirty drum

Black stripes (entirely black page)

Typically result from a dirty or damaged primary charge roller or a malfunctioning high-voltage power supply

Speckling on output

Clean the inside of the printer with a toner-safe vacuum to remove any excess toner particles

Vertical or horizontal lines

Typically caused by dirty feed rollers or a damaged photosensitive drum

Toner not fusing properly

The printout may smudge or smear when touched because the toner isn’t heated enough to bond with the paper, so check the fuser

Double images/echo images/ghosting

Condition in which the remnants of a previous printout appear on a new one. This can be resolved with replacing the drum

Incorrect chroma display

Occurs when the colors in the printout don’t match the expected output. To fix, ensure that the correct cartridges are placed in the appropriate slots

Colors missing from printout

Could be due to an empty or clogged ink or toner cartridge, replace the cartridge

Garbled printouts

Occur when the characters on the page are jumbled, corrupted, or unreadable. To fix this, first try reinstalling or updating the printer driver

Missing dots in printer characters or images

Printhead pins can wear down and leads to incomplete characters. To fix this, replace the printhead completely

Lose power connection

If the laptop loses power when moved, this is most likely a loose battery connection

OS not found error

This is an indication that the MBR (Master Boot Record) or GPT (Globally Unique ID Partition Table) is corrupted or faulty