2.1 Disassembling of various equipment and appliances

Disassembling electrical and electronic equipment requires careful attention to detail, knowledge of device construction, and adherence to safety protocols. Each type of equipment presents unique challenges due to variations in design, component placement, and complexity. This section explores the disassembly processes for ten common devices encountered in Kenyan electronics repair workshops, emphasizing practical techniques and safety.

2.1.1 Disassembling a Radio

Radios remain widely used in Kenya for information dissemination, especially in rural areas. Proper disassembly is vital to access internal components without causing damage.

Identification of External Fasteners and Panels

Radios typically have screws securing the casing, often located on the back or bottom. Some models include snap-fit plastic clips holding the front panel.

• Screw types: Commonly Phillips or flat-head screws; some older radios may use slotted screws.
• Clip detection: Gently applying pressure to edges reveals if clips are present.
• Labeling fasteners: Marking screw locations prevents confusion during reassembly.

Safe Removal of the Outer Casing

After removing screws, carefully pry open the casing using a plastic spudger to avoid scratching or breaking the plastic.

• Avoiding damage: Excessive force can crack the casing or damage internal wiring.
• Static precautions: Grounding oneself prevents electrostatic discharge that could harm sensitive circuits.

Handling Internal Components

Inside, the circuit board, speaker, and tuning mechanisms are exposed.

• Disconnecting wiring harnesses: Use small pliers or fingers to gently unplug connectors.
• Avoid pulling on wires: Pulling cables instead of connectors risks breakage.
• Inspecting for corrosion or damage: Corrosion on contacts is common in radios stored in humid environments.

Organizing Removed Parts

Keeping screws and small components sorted in labeled containers or magnetic trays facilitates smooth reassembly.

2.1.2 Disassembling a Television

Television sets, especially flat-panel models, are complex and require careful disassembly to avoid damage and electrical hazards.

Preliminary Safety Measures

Before disassembly, unplug the television and allow capacitors to discharge, as residual charge in power supply circuits can cause shocks.

• Use insulated gloves: When handling power boards.
• Discharge capacitors: Shorting terminals with a resistor if trained and equipped.

Removal of the Back Cover

The back cover is usually secured by multiple screws and clips.

• Screw locations: Around the perimeter and near ventilation slots.
• Plastic clips: Use a flat pry tool to release without cracking.

Accessing the Internal Boards

Once open, the mainboard, power supply board, and display panel connectors are visible.

• Disconnecting ribbon cables: These flat, delicate cables require lifting locking tabs before removal.
• Labeling connectors: Essential to avoid confusion during reassembly.

Handling the Display Panel

The LCD or LED panel is fragile.

• Avoid pressure on the screen: Causes permanent damage.
• Static precautions: Use anti-static mats and wrist straps.

2.1.3 Disassembling a Refrigerator

Refrigerators combine electrical and mechanical systems, requiring knowledge of both for safe disassembly.

Unplugging and Defrosting

Before disassembly, unplug the refrigerator and allow frost to melt to avoid water damage and electrical hazards.

• Water containment: Place towels to absorb dripping water.
• Door removal: May be necessary for full access.

Removing Panels to Access Electrical Components

Electrical components like the thermostat, compressor relay, and control board are behind panels.

• Panel fasteners: Screws or clips.
• Careful removal: Avoid damaging insulation or refrigerant lines.

Disconnecting Electrical Wiring

Identify and label wiring harnesses before unplugging.

• Use insulated tools: To prevent short circuits.
• Avoid pulling wires: Disconnect at connectors only.

Accessing Mechanical Parts

For compressor or fan motor inspection, remove protective covers.

• Note placement of mounting screws: For accurate reassembly.
• Check for refrigerant leaks: Avoid releasing refrigerant gases.

2.1.4 Disassembling an Electric Kettle

Electric kettles are common in Kenyan homes and offices, often requiring repair of heating elements or switches.

Removing the Base and Body

Most kettles have a detachable base connected to the power cord.

• Unscrew base fasteners: Usually located underneath.
• Separate body from base carefully: To access heating element terminals.

Accessing the Heating Element

The heating element is typically located at the bottom inside the kettle body.

• Remove protective covers or seals: To expose element terminals.
• Check for scale buildup: Common cause of failure.

Disconnecting Wiring and Switches

Switch assemblies and wiring are connected to the base.

• Label wires before disconnection: For correct reassembly.
• Inspect switches for mechanical wear: Switch failure is a frequent fault.

Safety Precautions

Avoid damage to waterproof seals that prevent water ingress into electrical parts.

2.1.5 Disassembling an Instant Shower

Instant showers are popular in Kenyan households for rapid water heating.

Isolating Power and Water Supply

Before disassembly, ensure power is off and water supply is shut to prevent electrical shock and water damage.

• Test with a multimeter: Confirm absence of voltage.
• Turn off water valves: Prevent leaks during work.

Removing the Outer Casing

Typically held by screws and plastic clips.

• Use appropriate screwdriver sizes: To avoid stripping screws.
• Pry gently: To release clips without breaking.

Accessing Heating Elements and Thermostat

Inside, the heating coil and thermostat are visible.

• Disconnect wiring carefully: Avoid pulling on wires.
• Check for signs of overheating or corrosion: Common fault indicators.

Inspecting Water Inlet and Outlet Connections

Ensure seals and connections are intact to prevent leaks.

2.1.6 Disassembling an Air Conditioning System

Air conditioners integrate electrical controls with refrigerant systems, requiring specialized handling.

Safety and Preparatory Steps

Disconnect power and ensure refrigerant is properly recovered before disassembly.

• Use refrigerant recovery equipment: To comply with environmental regulations.
• Wear protective gloves and goggles: Refrigerant can cause frostbite.

Removing External and Internal Units

Separate the indoor evaporator unit and outdoor condenser unit.

• Detach mounting brackets: Using appropriate tools.
• Label electrical and refrigerant connections: For accurate reconnection.

Accessing Electrical Controls and Circuit Boards

Control boards are often behind panels.

• Remove panel screws: Carefully to avoid damage.
• Handle circuit boards with anti-static precautions.

Handling Refrigerant Lines and Compressors

Avoid damaging refrigerant piping.

• Inspect for leaks or corrosion: Using leak detection sprays.
• Do not puncture lines: Refrigerant loss is costly and harmful.

2.1.7 Disassembling a Washing Machine

Washing machines involve electrical, mechanical, and water systems, demanding careful disassembly.

Disconnecting Power and Water Supplies

Ensure the machine is unplugged and water valves closed.

• Drain residual water: To prevent spills.
• Remove hoses if necessary: To access components.

Removing Outer Panels

Panels are secured by screws or clips.

• Identify panel types: Front, top, or back for specific access.
• Use proper tools: To avoid stripping fasteners.

Accessing Motor, Timer, and Control Boards

These electrical components are typically behind panels.

• Label wiring before disconnection.
• Check for signs of wear or damage.

Inspecting Drum and Mechanical Parts

Remove components to access the drum bearings and belts.

• Note alignment and tension: For correct reassembly.
• Inspect for debris or damage.

2.1.8 Disassembling a Mobile Phone

Mobile phones are compact with delicate components requiring precision tools.

Removing the Back Cover and Battery

Many phones have removable backs; some require heat or special tools.

• Use plastic pry tools: Avoid scratching or cracking.
• Disconnect the battery connector carefully: To prevent short circuits.

Accessing Internal Circuit Boards

After battery removal, screws securing the motherboard and screens are removed.

• Keep track of screw sizes and locations.
• Disconnect ribbon cables with care.

Handling Screen and Digitizer Assembly

The screen is fragile and often glued.

• Use heat guns or hair dryers: To soften adhesive.
• Avoid bending or applying pressure: To prevent damage.

Removing and Replacing Small Components

Includes cameras, speakers, and buttons.

• Use tweezers and magnification: For precision.
• Avoid static discharge: Use wrist straps.

2.1.9 Disassembling an Iron Box

Iron boxes are common household appliances with simple construction.

Removing the Bottom Plate

Typically secured by screws.

• Use the correct screwdriver: To prevent damage.

• Avoid losing screws: Store safely.

Accessing the Heating Element and Thermostat

Inside the soleplate, the heating element and thermostat are visible.

• Check for burnt or broken wires.
• Inspect thermostat for continuity.

Disconnecting Wiring and Switches

Wiring to the temperature control and power cord must be carefully disconnected.

• Label wires for reassembly.
• Inspect insulation for wear.

Safety Considerations

Ensure no damage to the soleplate surface and that all seals remain intact.

2.1.10 Disassembling a Set Top Box

Set top boxes are electronic devices that decode television signals.

Removing the Outer Casing

Usually secured with screws.

• Identify hidden screws under labels or rubber feet.
• Pry gently to release clips.

Accessing Internal Circuit Boards

Once open, main circuit boards and connectors are visible.

• Handle boards with anti-static precautions.
• Disconnect cables carefully.

Inspecting Power Supply and Tuner Modules

Modules are often separate PCBs.

• Check for bulging capacitors or burnt components.
• Test fuses and connectors.

Organizing Components for Reassembly

Keep screws and small parts sorted.

Chapter Summary

This chapter covers the essential processes involved in inspecting and testing electrical and electronic equipment and appliances. It begins with detailed guidance on disassembling various devices such as radios, televisions, refrigerators, electric kettles, instant showers, air conditioning systems, washing machines, mobile phones, iron boxes, and set-top boxes. The importance of sorting screws during disassembly is emphasized to ensure efficient reassembly and prevent damage. The chapter then addresses the inspection and testing of faulty equipment and appliances, highlighting common issues and diagnostic approaches. Various tests on power supply systems are explored, including voltage input tests, short circuit tests, and open circuit tests, each critical for verifying system integrity. Troubleshooting methods specific to different types of equipment are presented to aid in identifying and resolving faults effectively. Safety considerations during the testing of power supply systems are stressed to protect both the technician and the equipment. Finally, the chapter outlines relevant IEE regulations that govern safe and standardized practices in electrical testing and repairs.