CompTIA A+ Core 1 (220-1201)
1.0 Mobile Devices – Hardware Monitoring and Replacement
Overview
This section covers mobile device hardware components, common faults, monitoring techniques,
and correct replacement procedures. CompTIA exam questions are scenario-based and require
identifying symptoms, selecting the correct component, and applying proper safety and
replacement practices.
Mobile devices include laptops, smartphones, tablets, and 2-in-1 devices.
1. Battery
Description
Mobile devices use Lithium-Ion (Li-ion) or Lithium-Polymer (Li-Po) batteries to provide
portable power.
Common Problems and Symptoms

Device shuts down unexpectedly

Battery drains quickly

Battery does not charge

Device overheats

Battery swelling (critical failure)
Monitoring and Diagnostics

BIOS or UEFI battery health (laptops)

Operating system power settings

Manufacturer diagnostic tools

Physical inspection for swelling or heat
Replacement Techniques
Removable batteries can be replaced externally after powering off the device.
non-removable batteries require opening the device, disconnecting the battery first, and installing
a compatible replacement.
Example
A laptop works when plugged in but shuts down immediately when unplugged. This indicates a
failing battery.
2. Keyboard and Keys (Laptop)
Description
Laptop keyboards are integrated input devices connected to the motherboard using ribbon (ZIF)
cables.
Common Problems and Symptoms

Keys do not respond

Sticky or repeating keys

Entire keyboard not working

Random characters appear when typing
Monitoring and Troubleshooting

Test with an external USB keyboard

Test keyboard functionality in BIOS

Inspect ribbon cable connections
Replacement Techniques
Replacing a laptop keyboard usually involves removing the palm rest or top cover and carefully
disconnecting the ribbon cable.
Example
If a keyboard does not work in BIOS, the issue is hardware-related.
3. Random-Access Memory (RAM)
Description
RAM temporarily stores data used by the operating system and applications.
Mobile RAM Types

SO-DIMM (laptops)

LPDDR (phones and tablets, soldered)
Common Problems and Symptoms

Random restarts

Blue screen errors

Application crashes

Device fails to boot
Monitoring and Diagnostics

BIOS memory detection

Built-in diagnostic tools

Memory testing software
Replacement Techniques
Laptop RAM can be replaced by opening the memory compartment and installing compatible
modules.
RAM in phones and tablets is not replaceable.
Example
A laptop powers on but displays a black screen. Improperly seated RAM is a likely cause.
4. Hard Disk Drive (HDD) and Solid-State Drive (SSD)
Description
Storage devices store the operating system, applications, and user data.
Mobile Storage Types

2.5-inch HDD

2.5-inch SATA SSD

M.2 SATA or NVMe SSD

eMMC or UFS (phones and tablets)
Common Problems and Symptoms

Slow system performance

Freezing or crashing

Boot errors

Clicking noises (HDD)
Monitoring and Diagnostics

BIOS detection

SMART monitoring

Manufacturer diagnostic tools
Replacement Techniques
Laptop storage devices can be replaced and data cloned or the operating system reinstalled.
Phone and tablet storage is usually soldered and not replaceable.
Example
A laptop is very slow and makes clicking noises. This indicates a failing hard drive.
5. Wireless Cards (Wi-Fi and Bluetooth)
Description
Wireless cards enable Wi-Fi and Bluetooth connectivity.
Wireless Card Types

Mini-PCIe (older laptops)

M.2 (modern laptops)
Common Problems and Symptoms

No Wi-Fi networks detected

Bluetooth missing

Weak wireless signal
Monitoring and Diagnostics

BIOS detection

Device Manager

Driver verification

Antenna cable inspection
Replacement Techniques
Replacing a wireless card involves removing the card and reconnecting antenna cables correctly.
Example
A laptop detects Wi-Fi but has very weak signal strength. This often indicates loose antenna
cables.
6. Physical Privacy and Security Components
Biometrics
Description
Biometric devices include fingerprint readers, facial recognition cameras, and iris scanners used
for authentication.
Common Issues

Authentication failure

Sensor not detected

Dirty or damaged sensor
Replacement
Biometric components may be modular in laptops but are usually integrated in mobile phones.
Near-Field Communication (NFC)
Description
NFC enables short-range contactless communication for payments, access control, and device
pairing.
Key Characteristics

Very short operating range

Low power usage
Replacement
NFC components are often integrated into the motherboard or antenna assembly.
7. Wi-Fi Antenna Connector and Placement
Description
Wi-Fi antennas improve signal strength and reliability.
Common Problems

Weak signal

Frequent disconnections
Important Notes
Incorrect antenna routing or loose connectors can cause poor wireless performance even when
the wireless card is functional.
Example
A laptop only connects to Wi-Fi when close to the router. This suggests an antenna issue.
8. Camera and Webcam
Description
Cameras and webcams are used for video calls and authentication.
Common Problems and Symptoms

Black screen

Poor image quality

Camera not detected
Monitoring and Diagnostics

Operating system camera tests

BIOS diagnostics

Driver verification
Replacement Techniques
Webcams are typically located in the display bezel and connected via ribbon cables.
9. Microphone
Description
Microphones capture audio input and may be single microphones or microphone arrays.
Common Problems and Symptoms

No audio input

Distorted or low-quality sound
Replacement Techniques
Microphones are often integrated with webcams or charging port assemblies rather than being
standalone components.
Example
Audio works with a headset but not with the internal microphone, indicating an internal
microphone fault