I've been testing and adjusting my old motorola 7vt5 since the re-cap and It's looking much better with a functional focus control ;)

After about 20 minutes of watching i shut it off and headed back to my bedroom. When leaving I turned off the lights and noticed a flashing at my workbench. Looking at the tv in the dark I saw some flickering on the tube face. About every 10-20 seconds, what looked like watching a lightening storm through clouds briefly appeared on the screen. It did this for what must have been 5 minutes before the tube face was completely dark again.

I was just facinated. I've never seen such a thing before. Keep in mind the set was unplugged and away from any power source. I wish I coulda cought it on video (might have been too dark) I thought it was cool.

Anybody else who has an electrostatic set seen this before?

I have seen old b/w sets that weren't electrostatic do this. I don't think I've ever seen one carry on for 5 minutes.

John

Call the Ghostbusters! :D

Actually, I would say that it's stray electrons in the tube striking the still-charged face. That TV probably has no high voltage bleeder, and has no aquadag coating on the tube. So the high voltage just sits in there for awhile with no path to ground except through striking the phosphor. Kind of a miniaturized Ball-Lightning phenomenon.

Charles

My Motorola 9VT1 is an 8" electrostatic set and it does this all the time in the dark. It is normal for this type of set. It is rather strange because you can watch it slowly build up to a bright flash. I'm glad my wife has never noticed it because she would be convinced there's a ghost in it.

...

I haven't run my single electrostatic set in some time so I can't remember what kind of show it put on. The longest I've seen is from a 12" round Philco which flashes for many minutes. The prettiest light show is from a 68 Zenith color console which puts out a psychedelic kaleidoscope that lasts a few seconds.

Ah yes, the 68 zenith I sold Adam did the same thing. Soon as you turn it off, it gave out this neat circle of colors for a few seconds.

I always liked some of the sets that would simply have the picture shrink until it turned into a little bright dot when you turned them off. i wonder how many small kids were facinated by this after watchin the tube, and if it was ever harmful to the CRT to have that bright dot....

Hell, Jordan, that was half the fun of watching an old set...Watching the little white dot get smaller, & finally go away...I always wondered if the program was still "playing" in the little dot...Kinda on the same line of thinking if the light stays on in the fridge after you close the door...I was a WEIRD kid, worrying about stuff like that...And I ain't got any better as time went on...<grin>-Sandy G.

Hell, Jordan, that was half the fun of watching an old set...Watching the little white dot get smaller, & finally go away...I always wondered if the program was still "playing" in the little dot...Kinda on the same line of thinking if the light stays on in the fridge after you close the door...I was a WEIRD kid, worrying about stuff like that...And I ain't got any better as time went on...<grin>-Sandy G.
Sandy, as a kid, I shared the same fascination. (Loved that rainbow effect too!) :yes:

I'm not technical enough to know electrostatic from non, but my 10" Admiral bakelite set with original CRT does this same thing. The flickers seem to be in random "corners" of the screen but mostly the bottom right, they vary in brightness and there can be a few to several seconds between them. The set has to have run for a while before it will do this after shutting down. If I turn it off after only 5 or 10 minutes I will get a white dot but no flickering.

Growing up the sets I watched as a kid did more of the shriking to a dot routine and I don't remember any flickering like my Admiral makes.

With my rudimentary knowledge I was figuring it was a situation of left-over electrons like Charles describes above. Glad to read here that this doesn't appear to be a sign of any pending trouble.

My Motorola does exactly the same thing with the flashing.
I've also noticed, although I've only tried it with electromagnetic B&Ws, is if you turn the brightness down for a while before turning it off, the dot is brighter and lasts longer. I've always liked those sets where the picture settles down into a horiz line first before collapsing into a single dot.

Adam, you should try to keep the dot to a minimum, it could eventually burn a spot into the phosphor.

Someone mentioned once how to stop it, possibly a bleeder resistor on the HV or something, anyone know?

My brother's mid 80's Zenith has such an agressive natural glow to the CRT, you can cearly see it in the dark.

Even worse is my tek 545A scope. The screen *glows*. Hasn't been on for months but glows anyway.

Had an RCA HiLite 21FJP22 that did the same thing, but really dim. Just enough to notice it. Spooky to wake up at 2am and see that roundie outline just abut glowing...

In sets that show the dot or line at shut down, it's OK, or the manufacturer would have had to do something to prevent eating a lot of burned picture tubes. I saw this happen at Motorola on one early model of ttansistor B&W chassis. I can't remember the exact cause, but if you turned it off with the on-off switch, the tube was discharged enough before the raster shrank.. HOWEVER, the first factory run had the last person on the line pulling the line cord, and the video drive would go to cutoff immediately, with a spot appearing and burning the tube a long time after. Well, they were pulling the plug, putting the set in the box, and the burn would happen when the set was out of sight. When the box was opened, there was a burned tube! They had to put in a zener that pulled down the video drive as soon as the B+ died, causing a bright flash as the raster was collapsing but not yet down to a dot.

Another thing on those flashes - I vaguely recall seeing something similar around the edges of magnetically deflected tubes, maybe on turn on when the HV comes up before the filaments??? I wonder if there is any static buildup on the bezel - I'd be tempted to try running my hands around the face after turning it off to see if I could cause the flashing.

The prettiest light show is from a 68 Zenith color console which puts out a psychedelic kaleidoscope that lasts a few seconds.

Yup, here too!

Had an RCA HiLite 21FJP22 that did the same thing, but really dim. Just enough to notice it. Spooky to wake up at 2am and see that roundie outline just abut glowing...

Wow, same thing here. I used to have a roundie in my bedroom when I still lived w/my parents. It was creepy to see only that roundie "eye" glowing in a totally dark room.

We also had a Sony Trinitron 13" set, from about 1980 that would glow pretty bright for a long time...

My brother's mid 80's Zenith has such an agressive natural glow to the CRT

Since we've mentioned Zenith & Sony, might this have something to do with a high-quality CRT?

""Even worse is my tek 545A scope. The screen *glows*. Hasn't been on for months but glows anyway.""

I have one of those and it does exactly the same thing. It worried me for a while, I would unplug it and then still see it glowing. But then I read something somewhere about some of these old scope tubes having two layers of phosphor, the outer one of which is light-sensitive. So I took a flashlight and shined a focused beam of light at only part of the screen, and sure enough after I took the light away the screen glowed brightly where the light hit it and nowhere else. I also have a 515A that is the same way.

My '59 Motorola 21" B&W floor model used to do the dot in the middle of the screen. It would take roughly 5 minutes to slowly fade away. I just figured it was normal since I remember sets doing this when I was a kid.

This was when I first got it... and the set didn't play correctly anyway. Took me a long time to find the little bug causing the bad picture... it was one of those peaking coils... and it was well hidden in a little can. This was my first experience with Moto's failure-prone coils (I remember many people here spoke of them often).

After I changed the coil, the picture was perfect. Later, after I finished playing with the set for the day, I turned it off and quickly noticed that the little dot went away quickly... within a couple of seconds. Never again did that dot hang around. I don't know what difference the new peaking coil could have made for the dot, but, it apparently did something. That was the only thing I ever changed in this set, so, I have no other parts to blame it on.

I have a late 60's Truetone portable 21" b&w that does the same exact thing... bad picture and the dot when you turn it off. Will be interesting to see if it has a bad peaking coil... and if replacing it fixes both the bad pic AND the dot.

I was in the hospital in march of 2003, in the ICU, but I was alert...
I had a tv that when "OFF" at night I could STILL see program reception.
I thought I was NUTS for a while....

Couldn't SAY anything about it, I was intubated and on a ventilator..
Just imagine trying to get THAT across using charades or on a written note....

Until I finally got a remote in my hands and started turning the thing on and off and actually following program content after my eyes adjusted to the dark... on programs I had never seen before, switching across cable channels.

Turns out off really wasn't zero power. leakage?? circuitry??? hv shutdown?? :dunno:

It's not ghosting as in the rest of the thread, so sorry for the hijack.

Mark: If you're seeing a normal-size image, it's almost sure everything is running except that the video has been biased (almost) off

Charlie, I bet that peaking coil carries DC that bleeds off the video supply, and if it's open, the bleed can only happen through the CRT. [Just a guess -if you think I KNOW what I'm talking about, I will now explain Einstein's relativity.....] :)

Just a guess -if you think I KNOW what I'm talking about, I will now explain Einstein's relativity.....

Hey, no worries! I have a friend that would actually blame it on the flux-capacitor! :lmao:

I was in the hospital in march of 2003, in the ICU, but I was alert...
I had a tv that when "OFF" at night I could STILL see program reception.
I thought I was NUTS for a while....

Perhaps it was a telescreen, and Big Brother really WAS watching you ;)

#14, you mentioned that pulling the line cord rather than using the on/off control was causing problems.

I have my Admiral bakelite set hooked up to a VCR for tuner (remote control) purposes only, but the VCR doesn't have a switched outlet. I've tried to find an old analog cable box with a switched outlet without success. So I've put an in-line switch on the power (extension) cord for the TV, and this is how it gets turned on & off. Does anyone know if I'm asking for trouble with this practice?

here is what rca says. afterglow is a condition where some portion of the screen remains lit for a period of time after the set has been turned off. the duration of afterglow dedends on on the high voltage bleed off rate at the second anode of the picture tube. the bleedoff rate tends to be slower in a low leakage tube. hence a better than normal tube may exhibit more longer afterglow. the brightness and contrast setting at turn off the bleedoff rate will be faster.

this condition is quite normal and picture tubes exhibiting this condition are not eligible for warranty concerderation.

I'd say if anything this would be a better arrangement since there is less wear & tear on the power switch. Oftentimes they are none to sturdy.

#14, you mentioned that pulling the line cord rather than using the on/off control was causing problems.

I have my Admiral bakelite set hooked up to a VCR for tuner (remote control) purposes only, but the VCR doesn't have a switched outlet. I've tried to find an old analog cable box with a switched outlet without success. So I've put an in-line switch on the power (extension) cord for the TV, and this is how it gets turned on & off. Does anyone know if I'm asking for trouble with this practice?

If it hasn't burned the tube, then it's not a problem with this design. The Motos that had the problem had some sort of complicated multi-pole power switch to provide instant-on capability, IIRC. And as another post says, you are saving the switch in the set.

Perhaps it was a telescreen, and Big Brother really WAS watching you ;)


With all the tubes and wires, they didn't need to see me to know what I was doing... :D
Occasionally with a visitor, a nurse would come in and tell my visitor that unless some particular reading got back where it should be, visiting hours were over...... :nono:

Just tonight I was finishing up on the 630TS & had the 10BP4 out & face up in my lap so I could clean it. Yep, I saw some small but distinct flashes on the edge of the screen while I was holding it. I thought maybe static related but I could not duplicate it.