[johnd393]

Is there any reason to degauss (demagnetize) a crt projector?

 

[KBK]

Degaussing has to to with the metal grid at the front of a tri-color single tube CRT. these grids are made of ferrous materials. So, these devices can need degaussing, to be sure the grid has no residual magnetisim. Magnetism will shift the beam.. (as it tries to go through the proper holes for each color) creating color shifts, or color spots.


The tubes in a Projector have no grid (they are actually called 'electron masks', or 'shadow masks').

 

[stefuel]

Than why does an NEC projector offer this option in it's menu? Inquireing minds want to know.


Chip S.

 

[micj]

Any residue magnetism in the surrounding metals of the CRT tube will effect the path of the electron beam. The strength of any magnetism drops off at power of 3 rate I believe, so it's only the closeby metal to the tube that would have much effect. Over time, the earth's magnetic field and that of the projector's coil will tend to create some magnetism in the metal of the projector.


The degaussing ring runs along the top of the projector (if sitting on the floor) just under the top circuit board on an NEC PG. They recommend degaussing when ever changing position of the projector.


Regards,


Ira