Sometimes for short circuits between the heater and the cathode filament electron emitter of CRT (cathode ray tube), also called: or picture tubes picture tubes, TV or Monitor.

In these cases, the screen lights up intensely with one of three colors (red, green or blue). Sometimes when you turn the device could present a normal during the first few seconds and suddenly the screen goes completely blue, red or green with an intense shine. In some devices, it becomes active protection circuits or limiters X-ray and the horizontal oscillator source or stop working. (more...)