One of my older CRT TVs does not have a built-in degauss button and after sitting in the corner of the basement for a couple of years, it somehow got magnetized pretty badly. The top two-thirds became totally disclorored with the “rainbow” effect.Since the TV works excellent otherwise, I decided to fix the screen magnetization issue with a degaussing coil.
The basic operation principal of a degaussing coil is using a strong and gradual fading magnetic field which has an initial magnetic field many times stronger than the magnetization within the tube (typically in the shadow mask or the supporting frame). To produce such a strong magnetic field, we would need a very strong electromagnet. The simplest way is to find a pre-wound spool of magnetic wire and connect it to an AC source.
I bought a spool of 28 AWG magnetic wire which is roughly 1000ft. The spool has an inner diameter of roughly 1 inch. To increase the inductance of the coil and make it suitable for use with 110V main power, I added a steel rod as the core (the steel rod came from a used printer which was just a tad thinner than 1 inch). Here’s a picture of the degaussing coil I built:
To test the coil, you will have to be careful about the maximum current the magnetic wire coil can carry. Excessive current can cause the coil to melt and possibly burn! If you are unsure about the inductance of the coil, you probably want to use an autotransformer (Variac) and a AC current meter to determine what is the optimal operation voltage for your coil. Or, if you don’t have such tools, you will at least want to add a 100W light bulb between the coil and the power to limit the maximum current. If the light is dim when you power on the coil, then it indicates that your coil has sufficient inductance to operate using 110V AC power. If the light is very bright, you will have to adjust your design (i.e., adding a core with higher permissibility or add more turns to the winding).
If your construct is the same as mine, then the coil can operate at 110V AC with no overheating issue (current is at roughly 0.35 A when connected).
When degaussing, connect the power and move the coil slowly away from the TV screen to a few feet away in a gradual and circular motion.
