RCA CRT TV Question

[Console User]

I will try to explain the following the best I can.

I have noticed that when I turn off my 1986 RCA TV there is always a thin blue line in about the Middle of The CRT. Also, sometimes next to it is a small bluish-green mark. They fade away with time after the CRT cools down.

I was told this is normal is it and if so what do you call this phenomenon?

Also, when I turn the lights out in the room and shut my TV off I get the folllowing. A flash of light and also some little dots here and there on the CRT. I noticed one of the dots/marks flashed a little like a small line or small flame.

Also, I have noticed when the room is dark and you look at the CRT awhile after it has been shut off there is like this appearance of white cloud visible around the bottom or middle center of CRT. It's actually around the area I described with the blue mark. After time passes this goes away and the CRT becomes totally dark.

Also, why can the CRT appear with lightness even though it hasn't been on all evening and you just turn your lights off in the room for the night and this brightness on the CRT appears for a short time? Do CRT's sense room light even when they aren't in use?

One last question. Why when I sometimes turn on my TV with my RCA Converter Box I have no sound? However, if you turn everything off and restart it after a few times then its good to go?

[Console User]

Does any of the above situations described sound like a problem is developing or is it just normal for this type of TV from that Era? I just worry that someday it will go out.

[old_tv_nut]

Answers in BOLD

Originally Posted by Console User

I will try to explain the following the best I can.

I have noticed that when I turn off my 1986 RCA TV there is always a thin blue line in about the Middle of The CRT. Also, sometimes next to it is a small bluish-green mark. They fade away with time after the CRT cools down.


I was told this is normal is it and if so what do you call this phenomenon?

(Sounds like normal discharge of the remaining high voltage on the CRT. Nothing to worry about as long as operation is normal with the set on)

Also, when I turn the lights out in the room and shut my TV off I get the folllowing. A flash of light and also some little dots here and there on the CRT. I noticed one of the dots/marks flashed a little like a small line or small flame.
This may be random discharge of small static charge around the CRT. Again, no worries.

Also, I have noticed when the room is dark and you look at the CRT awhile after it has been shut off there is like this appearance of white cloud visible around the bottom or middle center of CRT. It's actually around the area I described with the blue mark. After time passes this goes away and the CRT becomes totally dark.

More of the same

Also, why can the CRT appear with lightness even though it hasn't been on all evening and you just turn your lights off in the room for the night and this brightness on the CRT appears for a short time? Do CRT's sense room light even when they aren't in use?

TV phosphors are designed for maximum efficiency with electron beam excitation. They are also designed to have short-to-medium decay of the brightness after excitation in order to prevent smearing of motion. However, these phosphors also can absorb a small amount of energy from light in the room (mainly blue or violet light]. The decay of emission, while nominally short, does not suddenly shut off when the excitation goes away - there is a tiny amount of phosphorescence (emission after the excitation is removed) in addition to the fluorescence (emission during excitation). If you have a LED flashlight, you may be able to demonstrate this by shining it on a small part of the screen and then turning it off in a dark room.

One last question. Why when I sometimes turn on my TV with my RCA Converter Box I have no sound? However, if you turn everything off and restart it after a few times then its good to go?
No idea, except that software-driven hardware is prone to glitches, so rebooting may be fixing a glitch. Has anyone else seen this problem?