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 emitted 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

Startup & Shutdown BSOD

BSOD errors that occur during system startup or shutdown, commonly caused by faulty hardware, drivers, or applications

Safe Mode

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

System Restore / Last Known Good Confiruration

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

Hardware Dianostics

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

Proprietary Crash Screens

Application-specific error messages or crash notifications that provide varying levels of troubleshooting information

Help Desk Ticket Documnetation

A record of a technical issue reported by a user; detailed descriptions and screenshots improve the troubleshooting process

Monitor Connectivity

Ensuring that the monitor’s power and signal cables are securely connected to the correct ports

Input Source Selection

The setting on a monitor that selects which input port to display video from

No Power Condition

A scenario where a computer shows no signs of power

Mutimeter Usage

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

Task Manager (Performance Monitoring)

A Windows utility used to view running processes, CPU/memory utilization, and troubleshoot performance issues

Windows Updates

Operating system patches that include security fixes, driver updates, and performance improvements

Disk Defragmentation

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

Power-Saving Mode (Laptops)

A feature that reduces CPU performance and other components to conserve battery life

Overheating

A condition where system components generate excessive heat

Monitoring Software

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

Burning Smell / Smoke

A severe hardware issue indicating electrical failure or short circuits

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

Application Crashes

When an application stops working unexpectedly, often accompanied by error messages or logs in Event Viewer

Reliability Monitor

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

Unusual Noises

Definition: Audible signs of hardware failure, such as:

• Rattling: Loose components.

• Scraping/Grinding: Hard drive issues.

• Clicking: Fan malfunctions.

• Popping: Blown capacitors.

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

Testing the Printer

• Test page / scan

  • Use Windows test page (not app)

• Diagnostics

  • Web-based printer utilities

  • Vendor-specific tools

  • Generic print utilities

Bad Output

• Lines on page

  • Inkjet → clean print heads

  • Laser → check for scratched drum

• Faded / blank pages

  • Low toner/ink

• Double/echo images / speckling

  • Dirty laser drum → ghost/shadow print

Garbled Print

• Wrong/bad driver (PCL vs PostScript mismatch)

• Test: Print Windows test page

  • If test page OK → app may send bad data

  • Upgrade/fix application

Paper Jam

• Removal:

  • Be careful → avoid tearing paper or damaging parts

• Causes:

  • Feed issues → check tray

  • Worn pickup rollers → replace via maintenance kit

  • Creased paper → check paper path & weight

Multiple Jobs Stuck in Queue

• Likely cause: Corrupted print job

  • Can crash/freeze spooler

  • Spooler usually auto-restarts

• Logs: Event Viewer → Windows-PrintService

• Tip: Identify and remove the bad job

Grinding Noises

• Never good → mechanical failure likely

• Causes:

  • Paper jam

  • Stalled carriage

• Action:

  • Follow manufacturer’s jam removal steps

  • May require service/replacement

Finishing Issues

• After printing → collating, binding, stapling

• Problems:

  • Staple jams → follow printer-specific process

  • Wrong hole punch → check driver, update if needed

Incorrect Page Orientation

• Portrait prints as landscape (or vice versa)

• Fix:

  • Check print settings & driver

  • Update driver if needed

  • Verify printer default settings

Tray Not Recognized

• Multi-tray printers → paper type/size must match

• Fix:

  • Driver config must match installed trays

  • Verify tray definitions in driver and printer console

Connectivity Issues

• Printer = network device → troubleshoot like any other

• Check:

  • Connection type (wired/wireless)

  • IP config (IP, subnet, gateway, DNS)

  • Printer server (if applicable)

No Network Connectivity

• Check link light

  • Is it plugged in?

• Ping tests (in order):

  1. 127.0.0.1 → protocol stack working?

  2. Local IP → config & adapter check

  3. Default gateway → local network OK?

  4. External IP (8.8.8.8, 9.9.9.9) → outside network OK?

Intermittent Wireless

Possible causes:

• Interference → other devices on the same frequency

• Weak signal → antenna placement

• Wrong channel → adjust manually if needed

• Multipath interference → flat/reflective surfaces

• Bad AP placement → move closer to users

Slow Speeds

• Verify:

  • End-to-end connectivity (ping, app login, speed test)

  • Each hop’s performance (utilization, errors, ACLs)

• Tools:

  • Packet capture → final proof

Limited / No Connectivity

• Windows warnings:

  • "Limited or No connectivity" / "No Internet Access"

• Check IP:

  • APIPA = only local connection

• If DHCP address OK → run ping tests

Jitter

• Real-time data (voice, video) needs regular packet timing

• Missed packets → no retransmission → choppy calls

• Jitter = variation in time between frames

Poor VoIP Quality

• Needs high speed + low latency

• Check:

  • Internet connection (speed test)

  • Router age/performance

  • Packet capture for analysis

Port Flapping

• Interface constantly going up/down

• Causes:

  • Bad cable or wiring

  • Faulty switch port

• Fix:

  • Swap ports

  • Replace hardware/cables

High Latency

• Delay between request and response

• Steps:

  • Measure response time at each hop

  • Use packet captures (microsecond detail)

  • Compare both ends

External Interference

• Predictable:

  • Fluorescent lights, microwaves, cordless phones, high power

• Unpredictable:

  • Multi-tenant buildings

• Measure:

  • Signal-to-noise ratio (SNR)

  • Performance Monitor

Signal-to-Noise Ratio (SNR)

• Ratio of usable signal vs interference

• Higher SNR = better connection

Authentication Issues

• Not a network issue → permission issue

• Check:

  • Credentials (username, password, MFA)

  • Session status → refresh / re-login

  • Packet capture to confirm connectivity & errors

Intermittent Internet

• Scope check:

  • Ongoing pings, traceroute, speed tests

• If ISP issue:

  • Contact support with account info

  • Review SLA (Service Level Agreement)

Poor battery health

• Replace the aging battery (limited recharge cycles)

• Weak signal drains battery

  • Use airplane mode for faster charging

• Turn off unused features (Wi-Fi, Bluetooth, GPS)

• Check app battery usage

  • iOS/iPadOS: Settings → Battery

  • Android: Settings → Battery

Swollen battery

• Gas buildup (self-contained) — Do NOT open (fire risk)

• Stop using immediately; dispose of properly

• Device damage possible, but safer than a fire

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)

Poor / no connectivity

• Cellular: signal strength, location (outdoor often better)

• Wi-Fi: range limits, interference, possible channel change

Liquid damage

• Many devices have Liquid Contact Indicators (LCI)

  • Turns color when exposed to moisture

• If wet: power off, remove case/cards/battery (if possible)

• Do NOT turn on, charge, heat, or shake the device

• Desiccant works better than rice

• Wait at least 24 hours before powering on

Overheating

• Device may shut down to prevent damage

• Heat sources: charging, CPU load, display brightness

• Check app CPU usage

• Avoid direct sunlight

Digitizer issues (touchscreen problems)

• iOS reset: power off/on or hold Power + Home/Volume (10 sec)

• Android reset: remove battery (if possible) or hold Power + Volume Down

  • Some devices have different key combos

Physically damaged ports

• Charging/data transfer issues

• Check for visible damage

• Often requires full system board replacement

Malware

• Symptoms: strange apps, pop-ups, overheating, high data/battery use

• Use a security scanner app

Cursor drift

• Screen moves/taps on its own (common in older devices)

• Use a touch calibration app

Unable to install apps

• Check storage space

• Confirm network connectivity

• Verify OS/app compatibility (update if needed)

• Clear store cache; check credentials; log out/in

Stylus not working

• Check stylus battery; recharge if needed

• Verify Bluetooth pairing

• Inspect for wear/damage

• Restart the device

Degraded performance

• Update OS and apps

• Free up storage

• Check for failing hardware (RAM/storage)

• Close unused background apps

• Older hardware may not run newer apps well

Incorrect Input Source

Display issue caused by the monitor being set to the wrong input

Dim Image

A display that appears too dark due to low brightness/contrast settings, power-saving modes, or backlight failure

No Video After Windows Loads

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

LCD Projector Bulbs

High-intensity metal-halide bulbs in projectors that require constant cooling

Fuzzy Image

A blurry display resulting from mismatched video resolution settings

Burn-in

A persistent ghost image on displays caused by static images left on the screen for extended periods

Dead Pixels

Non-functioning pixels that remain black on the screen

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

Monitor Audio Issues

Problems with sound output from monitors with built-in speakers. Solutions include checking monitor volume, HDMI/DisplayPort audio settings, and ensuring proper audio input selection.

Backlight Failure

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

Image Quality Problems

Visual issues like flickering, color distortions, or incorrect patterns. Common causes include bent cable pins, incorrect OS refresh rates, resolution mismatches, or faulty video cables.

Distorted Image and Geometry

A misaligned or oddly shaped display image, typically due to incorrect resolution, refresh rate settings, or faulty cables. Hardware acceleration may also need to be disabled for troubleshooting.

Sizing Issues (Scaling Problems)

User interface or image not properly scaled on the display. Adjustments can be made via OS resolution settings or scaling options within display settings.

Distorted Image (Artifacts)

Definition: Severe display distortion such as flashing lines, color blocks, or graphical artifacts. Possible causes:

• Hardware Failure: Damaged LCD panel.

• Bad Cable: Faulty or loose video cable.

• Video Adapter Failure: Defective GPU.

• Software Configuration: Corrupt or incorrect video drivers.

Read/Write Failure

Inability of a storage device to read data from or write data to a disk, often accompanied by errors like "Cannot read from source disk."

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.

Grinding Noises (Hard Drive)

Mechanical scraping or grinding sounds within a hard drive, typically due to physical damage or component failure, leading to data inaccessibility.

Troubleshooting Disk Failures

Definition: Steps include:

• Backing up data immediately.

• Checking for loose or damaged cables.

• Monitoring for overheating.

• Verifying power supply output.

• Running manufacturer-provided hard drive diagnostics.

Boot Failure Symtoms

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

Troubleshooting Boot Failures

Definition: Common steps include:

• Verifying physical cable connections.

• Checking BIOS boot sequence and settings.

• Testing with different SATA ports or computers.

• Inspecting for removable media interfering with boot.

Data Loss/Corruption

Occurs when storage devices fail, resulting in inaccessible or corrupted files

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 Times

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

Missing Drives in OS

Definition: A scenario where internal or external drives are not recognized by the operating system post-boot. Causes can include:

• Disconnected cables.

• No power to the drive.

• BIOS not detecting the drive.

• Network share issues (disconnected mapped drives).

Array Missing (RAID Controller Failure)

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