If you are using a tube amp, the tubes will eventually need to be replaced. Amplifiers use two types of tubes: power tubes and preamp tubes. Power tubes propel the adjusted signal out of the amp's speaker. Preamp tubes boost and shape the initially low incoming signal. When a tube begins to die out, you may notice inconsistencies in the sound coming out of the amp or an overall reduction in volume or quality. Replacing the tubes is as simple as pulling out the old ones and plugging in the new ones. It is important to exercise caution when handling tubes; if the amplifier was on recently, the tubes may be dangerously hot.
Both instrument amplifiers and car stereo amplifiers contain fuses. The purpose of a fuse is to protect components in a circuit from being damaged by sudden spikes in current. Fuses are designed to break if the current through them exceeds a certain amount. This opens the circuit and prevents it from functioning. Shorted components and power supply issues can cause a fuse to blow. If a fuse has blown in your amplifier, simply replace it with one of equal rating. However, it may be the case that some component of your amplifier is shorted.
The output end of the amplification process is the speaker. Speakers are separate from amplifiers, but many music amplifiers include built-in speakers. Hence, if something is wrong with your amp, it may actually be the speakers. When a speaker blows, this is often because the inductor coil that moves to produce sound becomes overheated and defective. This happens when the inductor receives a distorted or clipped signal from the amplifier.
All amplifiers include a number of other electric components, often in the form of capacitors and resistors. Solid-state amplifiers include transistors or integrated circuits instead of tubes for the amplification of signals. Capacitors can blow, causing a circuit to cease to function. Typically, a capacitor will blow if it receives a current that exceeds its maximum voltage for an extended period of time. Transistors can also fail over long periods of use or extreme conditions.
Any amplifier circuit involves countless wires and connections between its constituent parts. Sometimes, the failure of an amplifier is merely a failure of one or more connections. This can be in the form of a bad wire or a bad solder joint. The difficulty of fixing connection problems varies depending on the location and complexity of the connection. For example, input and output jacks with faulty wiring are very accessible and involve fairly simple wiring configurations.