Preventive Maintenance II – JSS2 Computer Hardware & GSM Repair Lesson Note (Third Term)

Preventive maintenance is the regular cleaning and checking of a computer to stop faults before they start.

• Bicycle example: a bicycle with an unoiled chain, soft tyres and rain damage will rust and stop moving.
• Computer: it is a machine too, so it needs routine servicing even when it works well today.
• Cost: repairing a broken computer costs much more than servicing it.
• Files: a computer that fails suddenly may cause us to lose our files.

Behavioural objectives

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

1. Define routine servicing.
2. State the effects of dust on a computer.
3. Clean the monitor, keyboard and mouse correctly.
4. Describe the steps of internal servicing.
5. Name three software housekeeping tasks.
6. Say how often each servicing task should be done.

What is routine servicing?

Routine servicing is the regular cleaning and checking of a computer to stop problems before they happen.

• Aim: to keep the computer cool, clean and working well.
• Prevention is better than cure: stopping a fault is cheaper and safer than repairing it.
• Two parts: hardware servicing (external and internal) and software housekeeping.

Why is dust dangerous to a computer?

Dust is the biggest enemy of a computer because the cooling fans suck it in from the room.

• Overheating: dust covers the parts like a thick blanket, so heat cannot escape and the computer may shut down or be damaged.
• Noise: the fans spin faster and louder to push air through the dust.
• Short circuits: thick, damp dust can carry electricity and cause a spark that can damage the motherboard.

What is external servicing?

External servicing is the cleaning of the outside parts of the computer, done every week.

The monitor

• Cloth: use a soft, lint-free cloth, such as a microfibre cloth.
• Liquid: never spray water directly on the screen, because liquid can seep inside and damage it.
• Screen cleaner: if you must use liquid, spray a tiny amount on the cloth first.

The keyboard

• Shaking: switch it off, turn it upside down and shake it gently to let out crumbs and hair.
• Brushing: use a small brush to clean between the keys.

The mouse

• Bottom: wipe the underside of the mouse.
• Optical mouse: keep the small “eye” (the red light) clear of hair and dirt.

What is internal servicing?

Internal servicing is the deeper cleaning of the inside of the system unit, done every 3 to 6 months by someone trained to open the computer safely.

Steps of internal servicing

1. Shut down the computer and unplug it from the power source.
2. Open the case carefully.
3. Blow out the dust: use a can of compressed air or a small electric blower on the fans and the power supply.
4. Check the cables: make sure all the cables inside (the “veins”) are plugged in tightly.
5. Renew the thermal paste: wipe off the old paste and apply a fresh drop between the CPU and its fan.
6. Close the case and test the computer.

Key points to remember

• Vacuum cleaner: do not use one inside a computer, because it can create static that damages the chips.
• Thermal paste: this is a special paste between the CPU and its fan that helps move heat away from the CPU.
• Old paste: after a year or two it dries out and cools the CPU less well.

How do external and internal servicing differ?

External servicing cleans the outside parts. Internal servicing cleans the inside of the system unit.

What is software housekeeping?

Software housekeeping is the cleaning and care of the programs and files inside the computer.

• Disk Cleanup: a Windows tool that deletes junk files the computer no longer needs, like throwing away old biscuit wrappers from your school bag.
• Emptying the Recycle Bin: files in the bin still take up space, so empty it to free room.
• Updating antivirus: the antivirus is the “security guard”, so it must know the latest viruses.

When should each servicing task be done?

Each task has a set time, shown in the checklist below.

Teacher’s note

• Demonstration: if possible, bring a can of compressed air or a small blower to class.
• Fan safety: show students how to hold the fan still while blowing air through it, so it does not spin too fast and break.

Evaluation

1. Why is it dangerous to spray water directly onto a computer screen?
2. Mention two things that happen to a computer when it is full of dust.
3. Why do we say that “Prevention is better than cure” in Information Technology?
4. What is the use of thermal paste inside the computer?
5. Name two software housekeeping tasks.

Assignment

Draw a servicing timetable with the headings Daily, Weekly, Monthly and Every 6 months. Write two tasks under each heading that you learnt in this lesson.