degausing

Overtime, magnetic field builds up aroung the CRT affecting the colors of the CRT. Degausing neutralizes this magnetic field.

In the early days of TV, then Colour TV, you could not move the TV set's position while it was working, because altered magnetic field of the Earth or nearby magnetic materials caused odd patchy results generally in the corners of the TV screen, in the case of Colour TV's there were strange patterns of colours, also mostly in the corners.

The solution was a coil which was wound around the front steel edge of the picture tube, and at the instant of switch-on, gave a pulse of AC through that coil.

The AC pulse automatically decreased within a second or two, leaving the Monitor steel edge frame fully demagnetised and now in the new position.

Likewise, the same was introduced into Computer Monitors,and most have automatic degaussing on switch-on, plus a manual one, in case of movement of monitor or adjacent magnetic metal items close by, while the monitor is being used.

In WW2, degaussing coils were wound around warships, to counteract the steel ship's magnetic effect on a magnetic mine.

The system worked quite well, and some 45 years ago, I used some of that highly flexible multicore cable, removing the sheath to obtain individual cores as high-current test leads in a Test Laboratory.

Kind Regards....