How to check if the switch socket on the appliance is faulty

Update:10-02-2020
Summary:

When our appliance fails, the first thing to suspect is […]

When our appliance fails, the first thing to suspect is the failure of internal parts, such as whether the socket is normal, whether the connector is normal, and whether the connector is normal. How to judge its failure? We can judge by the following four simplest methods:
1. First look
Observe with your eyes whether the various switches, buttons and knobs of the appliance are placed in the correct position, whether they are missing or damaged, whether the display and indicators on the display are normal, and whether the appearance of the machine is damaged. Disassemble the appliance, and check whether the internal connectors and wires are coming off or loose, and whether the printed circuit board is broken or damaged. Whether the components such as resistors, capacitors, transistors, and integrated blocks are scorched, cracked, damaged or broken, or de-soldered. Are any sensors, detection lights, adjustment switches, etc. damaged or displaced? Whether the transmission belt and gear are deformed, aging or falling off. Whether the transport mechanism, transmission link, etc. are displaced, deformed, and damaged, and whether the moving parts are flexible. Is there any ignition and smoke in the machine after the test is powered on? Whether the head is broken or dirty.
2. Sniff
Smell the appliance for scorching or other odors.
3. Hearing
Turn the appliance upside down and shake it, and listen for any loose or falling parts in the machine.
4. Manual
Use your hands to gently pull the wires, plugs, sockets, and components to see if they come off. Pull the relevant parts and try their tightness and flexibility. After power on, touch the power transformer, pass tube, integrated block or other related components to see if there is overheating.