I don’t know if this is in the right forum or not. If it’s not, I apologize. Anyway, here it is:
I bought a new RCA 27" television last Sunday. Last night, when I shut it off, I noticed that a faint blue dot toward the right side of the screen. I figured it might fade after a bit, but it didn’t. I thought it would go away if I pulled the plug, but it didn’t. I wanted to see if it was gone this morning, but my girlfriend had already turned it on when I woke up, and ti was there again when I shut it off. The question is, does anyone know what would cause this? I know it was giving off light since it was easier to see in the dark. It also looked like, in the dark, that there was a greyish-green crescent shape to its left. So, any ideas? (Aside from the sarcastic Poltergeist response.)
You remember that Twilight zone episode where people where being watched by Fedral Government through their t.v sets ?
Be afraid, be very afraid.
I’ve had a similar experience with a TV. The corner was discolored and would maintain a glow for a little while when the TV was shut off. Turns out there was a strong utility magnet resting on the housing of the TV right above that area of the screen. Moving the magnet would move the area of discoloration.
If there is an audio speaker or a telephone or any other kind of magnet near the discoloration, the magnetic field might be doing it. The interior of the picture tube is coated with electroluminescent material, if I’m not mistaken. No idea of the validity of this theory.
Hope this helps!
what you should do is stare for a very long time at the center of your screen. if you think you’ve stared long enough your wrong, just keep staring. when you no longer see the blue dot, just keep staring.
soon, you will be enlightened.
I’ve had an experience similar to Stoli’s. I bought a TV when I went off to college, and, because of a lack of space and of electrical outlets in our dorm room, I rested my answering machine on top of the TV. I only did this for about two or three days before I realized that this was causing a discoloration in the top right hand corner of the picture (reds were green, blues were purple). So I removed the answering machine and made sure there were no other appliances nearby.
However, the discolored spot never went away. The TV has been in three dorm rooms, two houses, and three apartments in the last six years, and has even been put in storage for more than a year, but when you plug it in and turn it on, the discolored spot is still there. Further, there is a little whitish spot in that corner which lingers for a few minutes after the set is turned off. The spot does disappear after about two-three minutes, though. I don’t know whether this helps or not, but could your TV have been exposed to electrical appliances/magnetic fields in the store? It doesn’t seem that the presence of the magnet or whatever has to be ongoing for the spot to continue to exist.
Magnetic fields can cause distortion in tvs and computer screens. Computer screens are almost always equipped with a handy dandy degausser that either goes off automatically when you start the monitor or can be triggered by the monitor controls (it’s that bWOWP! noise you hear when you turn it on). The degausser clears the magnetic distortion and returns the screen to normal. However, if the field that originally distorted it is still there, the distortion will come back.
The latest TV models might have a built in degausser, I’m not sure. However, if it doesn’t, you can schlep it down to a TV repair shop and say “hey, degauss this sucker for me”.
Not all distortions can be fixed by degaussing. It’s possible to permanently “kill” the pixels on a computer screen (and I assume a TV screen as well). On a long ago tech support call, I talked to a guy whose physics professor thought it would be really nifty to put a five inch magnet against a 17" monitor and hold it there for a couple of minutes as a class demonstration. He ended up killing the pixels directly against the magnet, and I had to tell this poor guy that his $500 monitor was now a piece of junk no longer covered by warranty.
But the spot is very small and only a few inches off the center of the screen, and there is no noticable discoloration when the set is on. As for being exposed in the store, I guess it’s possible, but there would have been several inches between the TV and the magnet while it was still in the box. I’ve seen the effects magnets have on TVs and monitors, but this doesn’t look the same. Maybe it’s just the color guns cooling down. I’m going to have a look when I get home today, and see if it’s still there after several hours. If it is, then I guess Big Brother really is watching. 
Physics is not my area of expertise but having been in electronics and tvs I may give some idea.
When your telly is working there is a huge voltage differance between the screen and the guns in the neck of the tube.
This is generated in several stages and is commonly over 24kV .This huge potential helps accelarate electrons fron the guns to the screen. The electrons being both particle and wave acquire kinetic energy which is given up as photons when they strike the screen.Phosphor os used as the coating inside the screen as this glows is the visible light spectrum.
When you switch of your tv this high potential remains but the supply of electrons is cut off and so is the disharge path.The only way for the screen to discharge is to give up the energy it has stored, it is now very similar to a capacitor.
The charge the screen has will find some path to leak away but those high energy electrons stored still have to give up their energy as photons.This discharge path may have a very high resistance(high voltages require good insulation )Even plastic will conduct a minute amount of current.The higher the resistance the discharge path has the longer it will take for those electrons to leak away.
They will alays leak away through the path of least resistance and that glowing spot on your screen is where that path is located.You can drag the electrons around with a magnet.