What year did the tv white dot dissapear. Ie; when you switched off the tv a white dot would appear and get smaller?
Exactly. As the capacitors discharged, the cathode ray would continue to emit electrons although no longer being controlled horizontally or vertically.
I haven't seen it on a CRT produced since the 80s. I assume they added technology to eliminate the white dot after then.
They found that the spot could cause discolouration of the phosphor on the tube face. A "spot swallower" circuit was added to bias the tube fully on when the power was turned off, dissipating the EHT charge quickly.
When I was growing up, we had a TV that showed a black dot smack dab in the middle of the picture all the time. My Dad said it was discoloration from the white dot when you turned it off. We all really learned to tune it out & not notice it, except when hockey was on. Then it was very distracting.
I remember a color Zenith we had in the early 80s. If you turned it on and then quickly off, as soon as a full image appeared, a ghost of that image would slowly fade from the picture tube.
What I remember is having a pair of pliers sitting on top of the TV ready to be used to change the channel. If you are of a certain age you know what I'm talking about ...
Though I was sad to have to do so, I literally threw away (as in took the thing in for e-waste recycling) my previous TV even though it was still in good working order. No one wants CRT TVs any more, even 32" HDTV CRTs.
I was in the same boat with my Sony Trinitron (in perfect working condition). I couldn't even give it away to a charity - they weren't interested!
When I was in college, we had both the pliers as well as a shim to jamb behind the tuner wheel to keep it on a channel!