Safe Handling, Tools and System Assembly
How do I take a computer apart and put it back together without harming myself or the hardware?
- Apply occupational health and safety (OHS) standards in the computer laboratory.
- Demonstrate correct use of an anti-static wrist strap to prevent electrostatic discharge.
- Select and use the correct tool for each hardware task.
- Perform a systematic disassembly and reassembly of a desktop computer.
Overview
This is the term's major practical unit. Two dangers sit in every service job: the danger to you (mains voltage, stored charge in the power supply, sharp metal edges) and the danger to the hardware (electrostatic discharge, dropped screws, forced connectors). Professional technicians work to a checklist, not from memory.
OHS in the computer lab
Follow these rules every session — they will be assessed as part of your practical mark.
Laboratory safety rules:
- Power off and unplug: Switch off at the wall and remove the power cord before opening any case.
- Never open the PSU or a CRT monitor: They store dangerous charge even when unplugged.
- No food or drink: Liquid on a board is usually fatal to the board.
- Dry hands, dry bench, no jewellery: Rings and metal bracelets short circuits waiting to happen.
- Lift correctly and clear the walkway: Cases and CRTs are heavy; trailing cables cause falls.
- Report damage immediately: Frayed cords and cracked plugs go out of service, not back in the cupboard.
Electrostatic discharge (ESD)
Your body can hold thousands of volts of static — far too little to hurt you, but enough to destroy a chip. Wear an anti-static wrist strap clipped to the bare metal chassis, or touch the chassis before handling components. Hold cards by their edges, never by the gold contacts or chips, and keep spare components in their anti-static bags until fitting.
Toolkit
A basic technician's kit and what each item is for.
Know the tool and its use:
- Philips and flat screwdrivers: Case, drive and board screws — magnetised tips help but keep them away from drives.
- Anti-static wrist strap and mat: Equalise your charge with the chassis.
- Needle-nose pliers and tweezers: Retrieve dropped screws and set jumpers.
- Cable ties and torch: Route airflow-friendly cabling; see into the case.
- Compressed air and soft brush: Remove dust from fans and heatsinks — never use a vacuum inside the case.
- Digital multimeter: Check PSU output and continuity.
Disassembly and assembly sequence
Disassemble in the reverse order of assembly, photographing each step and putting screws in labelled containers.
Assembly order:
- 1. Prepare: Anti-static strap on, case on the bench, PSU fitted into the case.
- 2. CPU: Lift the socket lever, align the corner triangle, drop in — never force — close the lever.
- 3. Thermal paste and cooler: A pea-sized dot, then seat the heatsink evenly and connect the fan header.
- 4. RAM: Match the notch, press both ends until the clips snap closed.
- 5. Motherboard into case: Standoffs first, then I/O shield, then screws — snug, not tight.
- 6. Drives and cables: SATA data and power, front-panel connectors, 24-pin and CPU power.
- 7. Check and boot: Recheck every connector, then power on and listen for a single POST beep.
Practical — Strip and rebuild a desktop
- Work in threes: technician, recorder, safety officer. Rotate roles.
- Complete the OHS checklist and sign it before touching the machine.
- Disassemble the system unit, photographing or sketching each stage and bagging the screws by stage.
- Reassemble in the correct order, then power on and confirm the machine reaches POST.
- Submit the safety checklist, the labelled component list and the boot evidence.
- Why must you never open a power supply unit?
Reveal answer
Its capacitors store a dangerous charge even after it is unplugged.
- How does an anti-static wrist strap protect components?
Reveal answer
It keeps your body at the same electrical potential as the chassis so static cannot discharge into the components.
- Why are standoffs used under the motherboard?
Reveal answer
To keep the board off the metal case and prevent short circuits.
- What is POST?
Reveal answer
The Power-On Self-Test — the firmware check of essential hardware at start-up.
- Why should screws be bagged and labelled during disassembly?
Reveal answer
Different lengths and threads are used in different places; wrong screws can damage the board or drives.
Write a one-page laboratory safety poster for your school computer room and ask your teacher to display it.