Consumer Electronics and Appliances Servicing
Consumer Electronics and Appliances Servicing is examined through safe fault diagnosis in TVs, washing machines, refrigerators, microwave ovens and small appliances.
What the exam tests
Servicing questions test systematic fault-finding in LED TVs, washing machines, refrigerators, microwave ovens, mixers, fans, inverters and SMPS-based appliances. The exam favours safe isolation, symptom-to-block diagnosis, component checks and correct replacement ratings over board-swapping.
Core rules
- SMPS: mains → EMI filter → bridge rectifier → reservoir capacitor → chopper → transformer → secondary rectifier/filter → feedback. The primary side is live; bulk capacitors hold dangerous charge after unplugging.
- LED TV: no picture but sound often points to backlight, LED driver or panel; no sound and no picture points to power supply or mainboard; check standby voltage first.
- Washing machine: fills but does not agitate → lid/safety switch, belt, motor capacitor, motor winding or control board; does not drain → drain pump/filter or pressure switch.
- Refrigerator: compressor not running → thermostat, PTC relay, overload, winding or supply; sealed-system faults need gauges and recovery equipment, not guesswork.
- Microwave: magnetron, high-voltage transformer, HV capacitor and HV diode. The capacitor can retain lethal voltage; discharge it properly.
Worked example
A washing machine fills normally but the drum does not turn in wash mode. The inlet and water level are therefore working. Check the lid switch, then the belt for slipping or breakage, then the motor run capacitor for bulging or loss of capacitance, then motor winding continuity, and finally the control board output. The reasoning is to follow the energy path and eliminate proven-good blocks, not to replace the board first.
Traps that cost marks
Working on a live SMPS primary; assuming a no-power TV needs a new panel; fitting a motor capacitor with the wrong capacitance or voltage rating; bypassing a lid switch; opening a microwave without discharging the HV capacitor; diagnosing a sealed refrigeration system without pressure measurements.