Eliminating device for colour killer band

A cathode ray tube may utilize a focus mask color-selection structure. The focus mask structure is susceptible to localized, transient short circuit events, or breakdown events. These events may be caused by conductive particulates that become free within the cathode ray tube and provide a short circuit between first and second layers of the focus mask. The breakdown events are undesirable because they may result in cross-strand currents causing mask strand magnetization that can interfere with a video image on the screen of the cathode ray tube. A rapid degaussing operation is initiated during the next subsequent vertical blanking period following detection of the breakdown event.