Equipment can malfunction for many different reasons. Mechanical contacts and parts can wear out; wires can overheat and burn open or short out; parts could be damaged by impact or abrasion; etc. Equipment may operate in a way far different than it had been designed to, or not work at all.
Typically, when equipment fails there does exist a sense of urgency to get it fixed and operational again. If the faulty equipment is a part of an assembly line, the entire assembly line could be down causing unexpected "time off" and lost revenue. If you are at a customers site to repair equipment, the customer may watch you, knowing that they are paying for every minute you spend fault finding and repairing their equipment. Either one of those scenarios - and you can find more, can put a great deal of pressure on you to solve the problem quickly.
So, what is troubleshooting? It is practise of analyzing the behavior or operation of a faulty circuit to work out what is wrong with the circuit. It then involves identifying the defective component(s) and repairing the circuit.
Depending on the particular equipment, fault finding can be a very challenging task. Now and again problems are easily diagnosed and the problem component easily visible. Other times the symptoms as well as the faulty component is often difficult to diagnose. A defective relay with visual signs of burning will be easy to spot, whereas an intermittent problem attributable to a high resistance connection can be much tougher to find.
What makes an expert Troubleshooter? One trait of expert troubleshooters is they are able to find virtually any fault in a reasonable quantity of time. Easy faults, complicated faults, they find them all. Another trait is they typically replace only the components which are defective. They appear to have a knack for finding out exactly what is wrong. No trial and error here. So what is their secret?
You might believe that an individual who has a very good understanding of how the equipment works, ought to be able to fault find it effectively. Being good at fault finding requires a lot more than this.
Expert troubleshooters have a good understanding of the operation of electrical components that are used in circuits they are familiar with, and even ones they are not. They use a system or approach that permits them to logically and systematically analyze a circuit and determine exactly what's wrong. They also understand and effectively use tools like prints, diagrams and test instruments to spot defective components. Finally, they have had the opportunity to develop and refine their troubleshooting skills. If you ever wish to fault find like the pros you will need to develop your skills in each of these areas.
You would need to be able to work out how the circuit works under normal conditions and what effect changing one of the circuit inputs has on the circuit operation. One example is, what happens to the overall circuit operation when a push button is pressed; which relays energy, which lights illuminate, does the pump start or stop, etc. You also need to be able to work out what effect a faulty component might have on the circuit operation.