Which component should be checked first if there is no voltage in the circuit?

In troubleshooting a circuit that is not receiving voltage, the contacts are typically the first component to check. This is because contacts, such as those found in relays or switches, can become dirty, corroded, or mechanically faulty over time. If the contacts are not making a proper connection, this can prevent voltage from flowing through the circuit, leading to the issue of no power being present.

Checking the contacts first allows the technician to assess one of the most common sources of failure in electrical circuits. If the contacts are functioning correctly, it would then be appropriate to move on to testing other components like the capacitor, thermistor, or transducer, which could also contribute to circuit issues but are generally less likely to be the immediate cause of a complete lack of voltage.

In contrast, while components like capacitors, thermistors, and transducers have their own roles within the circuit, they usually don't directly interrupt the flow of voltage like faulty contacts do. Thus, evaluating the contacts first streamlines the troubleshooting process, ensuring that the most likely culprit is addressed immediately.