Amplifiers: test controls, jacks and switching before faults become intermittent

Periodically move controls through their normal travel and test inputs, channels, loops and switching functions that are used less often.

If noise appears, note exactly when it occurs: while turning a control, touching a jack, on one channel only or after several minutes of operation. This information is far more useful than a general description such as “it makes noise”.

Avoid spraying products randomly into potentiometers; both product and procedure must be suitable for the component.