Degaussing ACRT Monitor

Manual Degaussing involved using a degaussing coil, which was held perpendicular to the screen a few feet away from the screen (and credit cards) ,energized , rotated parallel to the screen, slowly brought to the screen, moved around the screen, and progressively drawn away from the screen and rotated perpendicular again before being de-energized. Almost all CRTs? had a degaussing circuit built in, which would activate when the unit was turned on, and later CRT monitors had a degauss function, accessed from an on screen menu or a front panel button.

A degaussing coil is just an strong electromagnet running on alternating current; you can make one with a small transformer and a simple coil of (enough) wire (100 feet or so). Connect the low-voltage/high-current output from the transformer to the two ends of the spool of wire, and plug it in. If the fuse/breaker does not blow and the spool does not get too hot to handle, you have a degausser.

Degaussing was needed when the (often heavy) metal frame inside the CRT monitor became magnetized and produced a field which would discolor the screen image. Sonetimes it was also needed when the monitor was rotated with respect to the earth's magnetic field.

This is not true in the field of broadcast where CRT monitors are still heavily prefered for their far superior colour representation. Manual degaussing is commonly used to repair these expensive CRTs?.