Review of GSM Hardware – SS2 Computer Hardware & GSM Repair Lesson Note (Second Term)

A GSM phone is made up of four main hardware sections: power, display, audio and network. Each section has key components and common faults. Knowing the part that does each job lets a technician identify a fault and choose the simplest fix, such as cleaning or replacing a plug-in part.

Class: SS2

Subject: Computer Hardware and GSM Repair

Behavioural objectives

By the end of the lesson, students should be able to:

• compare the parts of a mobile phone to the parts of a human body;
• name the key components of the power, display, audio and network sections;
• describe the common faults of each section;
• suggest a simple fix for a given fault.

How is a mobile phone like a human body?

A mobile phone is like a human body. It has a skeleton (the frame), a brain (the CPU), a heart (the battery) and nerves (the circuit tracks).

In SS1, we learned about the different parts that make up a phone. Today, we will recap those parts and look at the most common “sicknesses” (faults) they suffer from. If you can’t identify the part, you can’t fix the fault.

What does the power section do? (The “heartbeat”)

This section makes sure the phone turns on and stays on.

• Key components: battery, battery connector, power IC and charging port.
• Common faults:
  1. Dead phone: The phone won’t turn on at all. This is often a faulty battery or a broken power IC.
  2. Charging problems: You plug it in, but nothing happens. This is usually a dirty or broken charging port (USB port).
  3. Battery drain: The phone turns on but dies in 30 minutes. The battery is likely “swollen” or old.

What does the display and light section do? (The “eyes”)

This is the part we interact with the most. It includes the LCD (Liquid Crystal Display) and the touch screen (digitiser).

• Key components: LCD screen, LED backlight and display connector.
• Common faults:
  1. White screen: The phone is on (you hear sounds), but the screen is plain white. This means the data isn’t reaching the LCD properly.
  2. Cracked touch: The screen looks fine, but it won’t respond when you tap on apps.
  3. Dark screen: You can see icons if you hold the phone under a bright lamp, but the screen has no light of its own. This is a “Light IC” or “coil” failure.

What does the audio section do? (The “mouth and ears”)

This section handles all the sounds: the music you hear and the voice you send.

• Key components:
  • Ringer/loudspeaker: for music and speakerphone.
  • Earpiece: for hearing the person calling you.
  • Microphone (mic): for sending your voice to the other person.
• Common faults:
  1. One-way audio: You can hear the caller, but they can’t hear you. This means the microphone is bad.
  2. Muffled sound: The music sounds “scratchy”. Usually, dust or iron filings are stuck in the speaker magnet.

What does the network section do? (The “signal”)

Without this section, a smartphone is just an expensive calculator. It connects the phone to the mast (base station).

• Key components: antenna, network IC (PA) and SIM card slot.
• Common faults:
  1. “No Service”: The phone is working, but it can’t find a network.
  2. “Emergency Calls Only”: The phone sees the network but isn’t allowed to connect.
  3. “Insert SIM”: The phone doesn’t recognise that a SIM card is inside. This is often caused by bent pins inside the SIM slot.

Recap table of sections, faults and fixes

Teacher’s “golden rule” for SS2

“Always start with the easiest fix first. Don’t pull out the hot air gun to heat a chip if the only problem is a dirty charging port! 90% of GSM faults are solved by cleaning, tightening, or replacing a simple plug-in part.”

Evaluation

1. Name the four main hardware sections of a GSM phone.
2. List the key components of the power section.
3. A caller can hear you only faintly…