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What Makes a TV Capacitor Go Bad?

Capacitors are common components used almost every kind of electronic device, including computers, radios and TVs. In a circuit, capacitors store electric charge, making them useful as noise filters in power supplies, and in television signal-generating and control applications. As with any manufactured component, TV capacitors can go bad, from age, manufacturing defects or damage from power surges.
  1. Description

    • The physical makeup of capacitors varies by type and capacitance value, though they all consist of a pair of metal plates or foils electrically separated by an insulator. Connected to a circuit, electric charges flow into the plates until they become full. The capacitor releases the charges at a later moment, slowly or rapidly. A capacitor can go bad a few ways. The insulator can break down and begin to conduct, ruining the capacitor̵7;s ability to store charge. The insulator can conduct with low resistance, forming a dead short in the circuit. The capacitor̵7;s connecting wires can break, preventing any charges from flowing into the component.

    Age

    • Aluminum electrolytic capacitors have a tendency to fail through age. They contain a chemical electrolyte paste that dries out after 15 to 20 years, especially if capacitor is in a hot environment. A dried-out capacitor loses its ability to store charge but usually does not cause a short-circuit. In a power supply, a capacitor removes low-frequency electrical noise from the voltage that runs the TV. If it dries out, that noise remains as an audible buzz or hum.

    Heat

    • Electronic components are notoriously heat-sensitive, and capacitors are no exception. Capacitors can work trouble-free for decades at room temperature, but, especially above 65C, the thin insulating layer deteriorates and fails in a few years. An overheated TV capacitor may fail suddenly, emitting a puff of foul-smelling, though not toxic, black smoke. Your TV likely has vents to allow air to circulate through the insides, keeping them cool. Make sure these vents are not blocked; otherwise, capacitors and other components will overheat.

    Defects

    • An improperly manufactured capacitor will fail prematurely, by losing its capacitance or by shorting the circuit. For an electrolytic capacitor, the manufacturer must formulate the electrolyte to an exact specification or risk this kind of failure. Other kinds of capacitors can also fail from poor materials or damage caused during the circuit-building process. These types of failures are uncommon; when they occur, they tend to affect a whole batch of manufactured parts.

    Voltage Surge

    • Every capacitor has a maximum voltage rating beyond which it suffers damage. The thin insulator will break down under excess voltage and begin to conduct, causing a short circuit. The normal voltages in the TV are well within a capacitor̵7;s safe zone; however, lightning strikes and other voltage surges in the household power may damage a TV̵7;s capacitors. It is a good practice to plug your TV into a power strip with surge protection to prevent this kind of problem.


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