Part of what he says is true. If a Trinitron's aperture grille is genuinely warped, it will never be the same again and you might as well pitch it. However, a warped grille is not the same thing as colour purity issues like the OP is having, and you will not necessarily cause a warped grille just by using a deguassing coil. The primary danger that a grille has is in part due to its nature of fine wires as opposed to a slot mask in conventional CRTs. When the television is subjected to stress, it is not impossible that these wires can bunch together. I've even seen stabilizer wires and frames of the grille get dislodged in places, causing a curved, or a "warped" picture, and it's a real shame to see because when it happens typically the rest of the image on the screen is fine. I'll always wonder what happened to the first PVM that I owned, because it had this problem. I continued to use it for years, but the upper right inch-and-a-half or so was always curved.
Anyway, while I suppose that it could happen from degaussing manually, by way of a particular set of wires becoming more or less permanently magnetized, I doubt this was anybody's fear when faced with colour purity problems and the need to degauss in order to fix it. Indeed, the risk of trading one issue (colour purity) for another (warped image) are rather low, and as some colour purity issues do come along with warped screen images, due to the nature of magnetization, you have little to lose by fixing the problem by way of manual degaussing. It is a fix that is not for the faint of heart, and absolutely not a thing to advise a consumer to do without experience if you are working for a company like Sony (they would much rather make a few more bucks by charging for the service anyway), but it is not something that cannot be done safely and properly. See here
. Yes, that is a FLAT Trinitron screen. Also works fine on the older, horizontally flat Trinitrons
, see the TV on the top.
Edit: I took a closer look at this PDF. It's no surprise they are telling you not to use a hand degausser. "The following adjustments should be made when a complete realignment is required or a new picture tube is installed."
The scenario is nothing like the OP's situation and closer to factory setup. Fixing colour purity doesn't require a complete realignment or a new picture tube.Edited by LiquidSnake - 1/10/14 at 8:42am