Final Project LI – JSS3 Computer Hardware & GSM Repair Lesson Note (Third Term)

The final computer project is a full repair task in which you open a faulty desktop computer, find the fault, fix it and test it.

Behavioural objectives

1. State the safety rules to follow before opening a system unit.
2. Carry out a pre-repair check by asking the right questions about a faulty computer.
3. Clean the inside of a computer and renew the CPU thermal paste.
4. Troubleshoot a “no display” fault by cleaning the RAM and checking the CMOS battery.
5. Reassemble, test and write a short report on a repaired computer.

What is the final computer repair project?

The project is a practical task in which you find the problem in a faulty desktop computer and make it run smoothly again.

• The goal: take a non-working or faulty desktop, find the fault, fix it and test it.
• The focus: full disassembly of the system unit, diagnosis and reassembly.
• The idea: many computers that “stop working” are not dead. They are dirty, overheated or need one small part repaired.

Tools and materials needed

• Screwdriver set: for opening the case and removing the cooler.
• Anti-static wrist strap: protects the parts from static electricity.
• Blower or compressed air: removes dust.
• Soft brush: loosens dust that air cannot move.
• Pencil eraser: cleans the RAM contacts.
• Isopropyl alcohol and tissue: remove old thermal paste.
• Thermal paste: goes between the CPU and the cooler.
• Spare CR2032 battery: replaces a dead CMOS battery.
• Cable ties: keep wires tidy.

What safety rules must you follow when repairing a computer?

Safety rules protect both you and the computer parts from harm.

• Switch off and unplug: shut the computer down and remove the power cable before opening the case.
• Control static: wear an anti-static wrist strap, or touch the bare metal part of the case before touching the motherboard.
• Do not open the PSU: the Power Supply Unit can hold a dangerous charge, so only clean its outside and fan area.
• Handle parts by the edges: avoid touching chips and gold contacts with your fingers.
• Work in a clean, dry place: keep liquids away from the open system unit.

What should you check before opening the computer?

The pre-repair check is a short set of questions, asked of yourself or the owner, that points you to the likely fault.

How do you clean the inside of a computer?

Internal cleaning is the removal of dust from the system unit so that heat can escape.

Why is dust dangerous to a computer?

• Traps heat: dust acts like a blanket over the parts.
• Damages chips: too much heat shortens the life of computer chips.
• Blocks fans: clogged fans spin badly, make noise and cool less.
• Nigerian setting: dust is a common cause of faults here, especially in the dry season.

Step 1: The blow-out

1. Switch off, unplug and take the computer to a well-ventilated place, such as a balcony.
2. Open the case and put on your anti-static strap.
3. Use a blower or compressed air to clean the PSU fan area.
4. Blow dust from the CPU heatsink (the metal fins over the processor).
5. Blow dust from the motherboard ports and slots.
6. Use a soft brush on dust that stays behind.

Step 2: Servicing the CPU thermal paste

Thermal paste is a special cream between the CPU and the metal cooler that passes heat from the chip to the cooler.

• Problem: after a few years the paste dries up and becomes like chalk.
• Effect: heat no longer passes well, and the computer runs hot and slow.

1. Switch off, unplug and gently remove the cooler.
2. Wipe off the old dry paste with a tissue and a drop of isopropyl alcohol.
3. Let the surfaces dry.
4. Apply a small pea-sized drop of new paste on the centre of the CPU.
5. Refit the cooler firmly and reconnect its fan cable.

How do you fix a “no display” fault?

A “no display” fault is when the computer is on and the fans spin, but the monitor stays black.

• First check: confirm the monitor is on and its cable is firmly connected at both ends.
• Next check: clean the RAM, then check the CMOS battery.
• Common cause: dirty RAM contacts are one of the most frequent causes of this fault.

Cleaning the RAM (“gold teeth”)

1. Unclip the RAM stick from the motherboard slot.
2. Rub the golden contacts (the “teeth”) gently with a pencil eraser until they shine.
3. Blow away any eraser crumbs.
4. Click the RAM back into the slot until both clips lock.

Checking the CMOS battery

The CMOS battery is the small silver button battery (CR2032) on the motherboard that keeps the time and BIOS settings.

• Sign of a dead battery: the computer forgets the date and time, or shows start-up errors.

1. Switch off and unplug the computer.
2. Use a small screwdriver to pop out the old battery.
3. Fit a new CR2032 with the same side facing up.
4. Reset the date and time when the computer starts.

What are common computer faults and their likely causes?

How do you reassemble and test the computer?

Final assembly is putting every part back neatly, then testing that the computer runs well.

Step 1: Cable management

• Keep wires tidy: do not let cables look like a “plate of spaghetti”.
• Use cable ties: tie wires away from the spinning fans.
• Reason: a wire touching a fan makes a loud noise or stops the cooling.

Step 2: The software health check

1. Check the temperature: use a simple monitoring program to see that the CPU is cool.
2. Listen: the computer should run quietly.
3. Check the antivirus: make sure it is working and updated so the computer does not get “sick” again.

What must the project report contain?

The project report is a short written record of the repair, and you must submit it to pass the project.

• The fault: what was wrong when you started.
• The action: what you did, for example “cleaned RAM” or “replaced PSU”.
• The result: whether the computer works now.

Qualities of a good technician

• Patient: checks one thing at a time without rushing.
• Clean: keeps tools, parts and the work area tidy.
• Honest: reports the real fault and the real result.

Evaluation

1. Why is dust dangerous to a computer motherboard?
2. What is the use of thermal paste?
3. If a computer beeps repeatedly when you turn it on, which part should you check first?
4. How do you protect computer parts from static electricity when you work on a motherboard?
5. List the three things a project report must show.

Assignment

A desktop computer runs very slowly, feels hot and makes a loud grinding noise. Write a short project report with the fault, the action and the result. List the steps you would take.