Revision of Practical Work SS3 Computer Hardware & GSM Repair Lesson Note

Subject: Computer Hardware and GSM Repair 

Class: SS3 

Topic: Hands-on Review of Key Practical Skills 

The Power of Your Hands

In ICT and GSM maintenance, “Knowing” is different from “Doing.” You can read a book about how to swim, but you only learn when you get into the water. The same applies to tech. This lesson is a final “Refresher” of the most important physical tasks you have learned over the last three years.

As you prepare for your final exams and your career, remember: A technician is only as good as their last successful repair. Let’s walk through the “Big Three” practical areas one last time.

Hardware Identification & Testing

Before you can fix a machine, you must be a “Master” of your tools. If you use the wrong tool, you will damage the device and lose the customer’s trust.

The “Big Three” Tools:

1. The Digital Multimeter: This is your “Eyes.” You use it to see electricity.
   1. Revision Tip: Always check your “Continuity” (Beep) mode first. If you touch the two probes together and it beeps, your meter is ready.
   2. Image of a digital multimeter showing the continuity and voltage settings
2. The DC Power Supply: This acts like a “Perfect Battery.” It tells you exactly how much current a phone or laptop is “drinking.”
3. The Hot Air Station (Blower): Used for removing chips.
   1. Revision Tip: Never keep the nozzle in one spot. Always move it in a small circle to spread the heat evenly.

The GSM Repair “Golden Steps”

Most phone faults follow a pattern. If you follow these steps, you will find the problem 90% of the time.

• Step A: The Visual Inspection. Open the phone and look for anything “ugly.” Is there green crust (corrosion) from water? Is a chip burnt or cracked?
• Step B: The Power Test. Connect the motherboard to the DC Power Supply.
  1. Reading 0.00A: The “Path” is broken (Open circuit).
  2. Reading >1.00A instantly: There is a “Short Circuit” (a component is touching ground).
• Step C: The “Short” Hunt. Use the Rosin Method. Coat the board in white smoke, inject power, and watch which part melts the smoke first. That is your “Villain.”

Computer Maintenance & Networking Practical

For computer systems, the most common practical tasks involve “Speed” and “Connectivity.”

Internal Cleaning & Upgrades:

• RAM Cleaning: If a computer beeps and refuses to show a picture, the first thing to do is remove the RAM and clean the golden “teeth” with a soft white eraser.
• Thermal Paste: If a laptop is getting too hot and shutting down, the “Paste” on top of the CPU has probably dried up. Clean it with alcohol and apply a small pea-sized drop of new paste.

Networking (Cable Crimping):

You must be able to make a Straight-Through or Cross-Over cable using an RJ45 connector and a Crimping Tool.

• Color Code (T568B): Orange-White, Orange, Green-White, Blue, Blue-White, Green, Brown-White, Brown.
• The Secret: Make sure the copper wires go all the way to the very end of the plastic plug before you “Squeeze” the tool.

Safety & Ethics in the Lab

As we revise, we must not forget the “Human” side of our work.

• ESD (Static) Protection: Your body carries enough electricity to kill a 200,000 Naira motherboard. Always touch a metal surface or wear an anti-static wrist strap before you touch a board.
• Data Privacy: If you are testing a repaired phone, do not open the gallery. Testing the camera does not mean looking at the customer’s family photos.
• Workshop Cleanliness: A professional leaves their workbench cleaner than they found it. Put your screws in a magnet tray so they don’t fall on the floor.

Summary: Your Practical “Cheat Sheet”

If you feel confused during a practical exam, stop and breathe. Follow this logic:

1. Identify the symptom (What is it doing/not doing?).
2. Isolate the fault (Is it the Battery? The Screen? The Software?).
3. Measure (Use your Multimeter or Power Supply to confirm).
4. Replace/Repair (Soldering or Swapping parts).
5. Verify (Test it three times before you say it is “Fixed”).

Review & Hands-on Practice

1. The Multimeter Challenge: Set your meter to Diode mode. Find any “Scrap” board and see if you can find a capacitor that is connected to the Ground.
2. The Current Reading Quiz: If a phone draws 0.05A and stops when you press the power button, is the problem Hardware or Software? (Answer: Usually Software/Bootloader).
3. The Crimp Test: Take a piece of CAT6 cable and see if you can arrange the 8 colors in the correct T568B order in under 60 seconds.
4. The Diagnosis Case: A laptop turns on, but the screen stays black. List three things you would check first.