CompTIA A+: Troubleshooting Computers

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Module 13:

Troubleshooting computers is a cornerstone skill for CompTIA A+ professionals, enabling them to diagnose and resolve various computer issues.

Let’s explore the essential steps and techniques:

Define the Problem:

  • The first step in troubleshooting is identifying and defining the problem. This involves gathering information from the user, observing the issue, and understanding its symptoms.

Establish a Theory:

  • Based on the problem’s symptoms and your knowledge, create a theory about what might be causing the issue. Consider hardware, software, and user-related factors.
  • What to look for
    • Work area suitability (customers wont know)
    • Audio cues (device noise)
    • Visual cues (look for damage)
    • Connections (maybe something slightly unplugged)
    • Ventilation (check airflow is OK)
    • Check indication warning lights
    • Use sense of smell (burning smells?)
    • Power – Check Power supply, check breakers.
    • Is it ON? – Turn it on.
    • Connections – Unplug and plug back in yourself.
    • Reboot / Hard reset
    • System Updates required? Check yourself
    • Boot logs – Disk boot prevention?
    • Peripheral devices – Unplug and plug back in yourself.
    • Internal connections – Unplug and plug back in yourself, also look for chip walk.
    • Optimization – Slow speeds, boot etc.
    • Configuration tools – Scanners etc.
    • Start working from inside to out when cleaning the PC
    • Recommended anti-virus software like Norton or McAfee
    • Always Backup the PC before you begin work
    • Check for system updates
    • Check for driver updates
    • System recovery as needed
    • Firmware updates
    • Program optimizer
    • Do not update unnecessarily you could cause more harm

Test the Theory:

  • To confirm or refute your theory, perform diagnostic tests and experiments. This might involve running system checks, using diagnostic software, or re-creating the issue.

Identify the Root Cause:

  • Once you’ve pinpointed the underlying cause, document it. This is crucial for future reference and resolution.

Implement a Solution:

  • Apply the appropriate fix for the problem. This could involve hardware replacements, software updates, configuration changes, or user guidance.

Verify the Solution:

  • After implementing the solution, test the system to ensure the problem is resolved. This involves confirming that the issue’s symptoms no longer exist.

Document the Solution:

  • Document the problem, the steps taken to diagnose it, the theory, the root cause, and the solution. This documentation helps in future troubleshooting efforts and can be valuable for others.

Preventive Measures:

  • Troubleshooting isn’t only about fixing issues; it’s also about preventing them. CompTIA A+ professionals should encourage proactive measures like regular backups, software updates, and security best practices to prevent recurring problems.

User Communication:

  • Effective communication with users is vital during troubleshooting. Explain the issue and solution in non-technical terms, ensuring they understand the resolution.

Common Issues

  • Temperature
  • Humidity
  • Spills
  • Electrostatic discharge
  • Electromagnetic interference
  • Dirt
  • PSU
  • Monitor
  • Keyboard

Common Troubleshooting Scenarios:

CompTIA A+ professionals encounter a range of common scenarios, such as:

  • Boot Errors: Address issues preventing a computer from starting.
  • Blue Screen of Death (BSOD): Diagnose and resolve system crashes.
  • Network Connectivity Problems: Troubleshoot network issues.
  • Software Errors: Resolve software crashes and glitches.
  • Hardware Failures: Identify and replace malfunctioning hardware components.
  • Peripheral Issues: Diagnose problems with printers, monitors, and other peripherals.

Remote Troubleshooting:

  • In today’s digital age, remote troubleshooting is common. Learn remote support tools and techniques to assist users from a distance.

Continuous Learning:

  • The IT landscape is ever evolving, so staying current with the latest technologies and troubleshooting methods is essential for CompTIA A+ professionals.

Audible Codes

During the BIOS boot you may here a series of beeps, here is what they are telling you.

Audible code Meaning
One short beep System OK
Two short beeps Post Error
No beep Motherboard or power issue
Repeating short beeps Motherboard or power issue
Single continuous beep Keyboard, motherboard or power issue
One long beep one short beep Motherboard issue
One long beep two short beeps Display adapter issue

Visual Codes

Code Error
100-199 Motherboard error
200-299 Memory error
300-399 Keyboard error
1400-1499 Printer error
1700-1799 Hard drive error

System Configuration Utility

The system configuration utility gives you access to all the main installed system configuration tools. Just enter the following command in the command prompt:


Disaster Recovery

Use boot logs to troubleshoot problems.
Boot logs show drivers, services and resources used when booting.
Look for keywords like “Load Failed” or “Did not load driver”.

Booting into safe mode

  • Press F8 immediately after the post process.
  • Select Safe boot
  • Can use debugging mode
  • Can disable automatic restart upon failure
  • Can reboot to last known good configuration
  • Can refresh PC so you don’t lose any files
Recovery Methods
  • Recovery images
  • Rescue CD’S
  • Rescue Partitions
  • Windows recovery tool on USB
Advanced Recovery Tools
  • Create a recovery drive
  • Configure system restore
  • PC refresh
Backup and Restore
  • Perform frequent backups
  • Get familiar with the restore tool
  • PC refresh and reset
  • Refresh, Reinstall’s windows but your data remains
  • Reset completely cleans the drive


Preventative Maintenance

  • Check disk utility
  • Disk Defragmentation
  • Windows updates
  • Firmware updates
  • Malware definitions

Preventative Tasks

  • Update Virus and malware software
  • Backup data
  • Defrag drives
  • Clean up unnecessary files
  • Clean the exterior of PC
  • Scan files for errors (CHKDISK.exe)
  • Ensure fans are clean and working
  • Check power supply

Troubleshooting Networks

  • No connectivity?
  • Limited connectivity?
  • Intermittent connectivity?
  • Slow transfer speed?
  • IP conflict?
  • Low RF signal?
  • SSID not found?

Troubleshooting Processor and Drive Issues

  • Check power supply.
  • Check default settings.
  • Check the CMOS battery.
  • Check cable connections to motherboard.
  • Check drive connections and signs of over heating.
  • Test parts in another PC.

Repair Vs Refurbish?

It’s down to you to advise the customer which is best.

Troubleshooting is a skill that empowers CompTIA A+ professionals to diagnose and resolve a wide range of computer issues. By following structured steps, maintaining excellent communication, and continuously improving their knowledge, A+ professionals ensure the efficient functioning of computer systems and a seamless user experience.

You can find all of our CompTIA A+ guides here:

We also have guides for the CompTIA Security+ here:


Hirens Boot CD:

Luke Barber

Hello, fellow tech enthusiasts! I'm Luke, a passionate learner and explorer in the vast realms of technology. Welcome to my digital space where I share the insights and adventures gained from my journey into the fascinating worlds of Arduino, Python, Linux, Ethical Hacking, and beyond. Armed with qualifications including CompTIA A+, Sec+, Cisco CCNA, Unix/Linux and Bash Shell Scripting, JavaScript Application Programming, Python Programming and Ethical Hacking, I thrive in the ever-evolving landscape of coding, computers, and networks. As a tech enthusiast, I'm on a mission to simplify the complexities of technology through my blogs, offering a glimpse into the marvels of Arduino, Python, Linux, and Ethical Hacking techniques. Whether you're a fellow coder or a curious mind, I invite you to join me on this journey of continuous learning and discovery.

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