Disassembling a Computer – JSS2 Computer Hardware & GSM Repair Lesson Note (First Term)

Disassembling a computer is the careful removal of its parts from the system unit in a set order, and reassembling is putting them back correctly.

Behavioural objectives

1. Define disassembling and reassembling a computer.
2. State the safety rules to follow before opening a system unit.
3. List the tools used to open a computer.
4. Describe, in order, the steps for taking a computer apart.
5. Identify the motherboard, RAM, CPU fan, CMOS battery and power supply.
6. Reassemble the parts and troubleshoot a computer that will not start.

Why do we disassemble a computer?

We open a computer to clean it, repair it or upgrade it.

• Cleaning: remove dust from the fans and the motherboard.
• Repair: replace a faulty part such as a hard drive.
• Upgrade: add or change a part, for example more RAM.

What safety rules must you follow before opening a computer?

Shut down, unplug, discharge and ground yourself before you touch any part inside the case.

• Static electricity: a small electric charge on your body, like the shock from a doorknob. It can damage computer parts.

1. Power down: shut down Windows and unplug the power cable from the wall.
2. Drain power: press the power button once after unplugging to release leftover electricity.
3. Ground yourself: touch a metal part of the case or wear an anti-static wrist strap.
4. Organise: keep screws in a small bowl or on a magnetic mat. A lost screw can rattle inside the case.

What tools are used to open a computer?

The main tools are a Phillips screwdriver, an anti-static strap, a small brush and a screw container.

What are the steps for disassembling a computer?

Disassembly has four steps, and we always work from the outside to the inside.

Step 1: Open the case

• Side panel: find it on the side of the system unit.
• Screws: there are usually two large screws at the back. Remove them.
• Slide off: slide the panel away from the case.

Step 2: Unplug the cables

• Rule: unplug the cables before you remove any big part.
• Power cables: they come from the Power Supply Unit, the big silver box.
• Data cables (SATA): usually thin flat cables joining the hard drive to the motherboard.

Step 3: Remove the RAM and expansion cards

• RAM: push down the clips at both ends of the slot. The stick pops up.
• Handling RAM: lift it by the edges. Never touch the gold pins with your fingers.
• Expansion cards: unscrew them from the back frame and pull them straight up.

Step 4: Remove the storage and power

• Hard drive: unscrew it from its bay, which is its shelf in the case.
• Power Supply Unit (PSU): unscrew it carefully, because it is heavy.

What are the main parts you should identify?

After removal, you should name each part and say what it does.

How do you reassemble a computer?

Reassembling means doing the disassembly steps in reverse order.

1. Motherboard first: make sure the motherboard is screwed in tightly.
2. Big parts: put the Power Supply and hard drive back in their places and screw them in.
3. Expansion cards: push them straight down and screw them to the back frame.
4. RAM (the click rule): push the RAM into its slot until you hear a click.
5. Cables: plug the power cables and SATA cables back in. Power connectors have a latch that clicks when secure.
6. Double check: look for loose screws or wires that could catch in the fans.
7. Close and test: refit the side panel, plug in the power and switch on.

What should you check if the computer does not turn on?

Check the RAM, the main power cable and the PSU switch first.

• RAM: is it pushed in all the way? This is the most common mistake.
• 24-pin cable: is the big 24-pin power cable plugged into the motherboard?
• PSU switch: did you flip the switch at the back of the Power Supply to on?

Class practical activity

• Observation: watch the teacher show how to handle a RAM stick.
• Identification: point to the SATA cable and the Power Supply.
• Practice: in groups of four, open the side panel and identify the parts without moving them.

Teacher’s note

• Never open the PSU: students must not open the Power Supply Unit, the silver box.
• Reason: it can hold high voltage even when unplugged, which is dangerous.

Evaluation

1. Why should we touch a metal object before touching the inside of a computer?
2. What is the very first thing you should do before opening a system unit?
3. How do you know that a RAM stick has been properly installed?
4. Why is it important to keep screws in a container?
5. State three things to check when a computer will not start after reassembly.

Assignment

In your notebook, list the four steps of disassembling a computer in order, and write one safety rule for each step.