Old television danger?

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On Mon, 24 Sep 2007 19:43:39 -0400, "Ralph Mowery"

Right now the end of the very back of the tube still has components (coil and green board). I'll clip the glass when I can finally see the end of the tube's end. Right - I hope....
-- Oren
"If things get any worse, I'll have to ask you to stop helping me."
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On Mon, 24 Sep 2007 19:43:39 -0400, "Ralph Mowery"

Worked like a champ! I used channel lock pliers and snapped it right off at the very end.
Thanks.
-- Oren
..through the use of electrical or duct tape, achieve the configuration in the photo..
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After years not plugged in the charge should be long gone. On the other hand there is another danger. It has a large glass envelop. You want to be careful with it. You don't want to break it with out proper protection for yourself and anyone else around. They are not real fragile, but they can be dangerous.
--
Joseph Meehan

Dia \'s Muire duit
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On Sun, 23 Sep 2007 18:54:43 -0400, "Joseph Meehan"

Breaking the "tube", right? I will use help to take the CRT out. -- Oren
"The voices in my head may not be real, but they have some good ideas!"
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wrote:

I had an big old console TV several years ago that I needed to discard. Since our town only took garbage in regulation-sized garbage cans, I had to break it down into rather small pieces. My biggest worry was the picture tube, since I had heard that the effect of breaking a large tube could be measured on the Richter Scale. I dragged the TV out to the back yard, covered it with heavy quilts like movers use, I dressed in enough layers of clothing to go exploring Antarctica, I wore an army surplus gas mask (to protect my face, not because of any gases), a steel helmet, and a pair of fireman's gloves. If I hadn't been young and impulsive, I probably would have taken the time to prepare my will. Then I reached over from one side so I would be shielded by the wood console, took a pair of pliers, and clipped off the nipple on the back of the picture tube. What happened next was kind of like the sound you get from opening a beer bottle. A brief Pffft, and it was over. If it had happened during modern times, it would be on YouTube now. I used a thick piece of shielded cable and shorted every dangerous looking connection to ground, but didn't get any sparks or other signs of residual voltage. Then I removed and smashed the picture tube and unfastened every screw in sight. It was a bit of work twisting the chassis into a shape that would fit in the garbage can, and I needed a chainsaw to deal with the cabinet, but I eventually got the whole thing into garbage cans over the course of a few weeks. In the end, it was much easier than the washing machine.
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Nick Danger wrote:

Clipping off the nipple at the extreme back end is relatively safe and is a very good idea. Else the tube has 16 pounds pressing in on every square inch of surface.

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bud-- wrote:

14.7 pounds, unless you're a few feet underwater, but who's counting....
Yes, a CRT implosion can be pretty scary. back around 1952 when I was a kid working after school at Bud Fiske's Radio & TV shop in San Francisco I was bringing a big B&W TV console chassis with CRT attached back to the shop in my car.
I just set it on the back seat and when I slammed on the brakes for "whatever" it tipped forward, the neck of the CRT hit the back of the front seat and snapped off, sucking the tube base and gun assembly into the back of the tube so hard it punched through its face.
What a mess! And what a red face I had when I had to explain what happened.
I've never forgotten the boss's words to me when I got back to the shop.
He said, "Jeff, for a smart kid you do stupid pretty good."
Jeff
<snipped>
--
Jeffry Wisnia
(W1BSV + Brass Rat \'57 EE)
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Jeff Wisnia wrote:

Sorry, I was using the new math (probably remembered 1/2 g).

At high school, a couple teachers tossed a 7" CRT into an empty classroom and quick closed the door. There was glass everywhere - on top of lights, on top of window casings.
If they shatter when they break you can have glass shrapnel. I was taught to give a lot of respect to exposed CRTs.
-- bud--
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Good idea...... You never know what tv shows were watched on that tube. If the user watched all sorts of violence, that tube could blow you to kingdom come. If they watched all kids cartoons, you will just laugh when it explodes, and I can not tell you on a public newsgroup, what would happen if that tv set was used to watch porn videos, and the CRT blew..... (You'll have to use your own imagination).
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Oren wrote:

The "Danger" comes from getting zapped and dropping the sucker on your toe!
Other than that, it's no more hazardous than a Taser (actually, quite a bit less).
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wrote:

Voice of a Taser experience? :)
-- Oren
"If things get any worse, I'll have to ask you to stop helping me."
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Like every one else says, I doubt if there is any energy left but if you want to play it safe discharge the high voltage on the picture tube before doing anything. 2 other safety rules taught when I worked for Zenith: when dealing with high voltage always work with one hand in your pocket and never work alone. You never know what may happen with a picture tube.

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The number would be negative. Doing that will charge it up again, if the high voltage circuit still works.
As to tube versus transistor, I think the voltages at picture tube are about the same. The voltage was about 10,000 for B&W sets and went to 25,000 for color sets.
Also big screens, which mean the distance from the electron gun to the screen has to be greater, need somewhat higher voltage.
Most of it is still there when you turn the set off, but slowly leaks back, probably through a high ohm resistor put in there for just that purpose. The big wire on the side of the tube is the anode connector, and the anode is the the inside of the tv screen.
The cathode is in the neck, partly covered by the deflection coils. Turn the coils on a B&W and you can make the image turn upside down. Or you can use a magnet to distort the picture.
On color, it's risky to move anything because it's hard to reposition later. And a magnet can leave it "gaussed" so that the right color beams don't go through the right holes. They all have autmatic degaussing these days, even in 1987, but it takes several or many times turning the set on for it to work.
They used to put the high voltage parts in a metal cage for safety, but to make the sets lighter they got rid of all of that!!!

I broke the neck off a few picture tubes. If you just crack t hem it's fun to hear the noise of the air seeping in, and fun to look at the beautifully designed electron "gun". One 9inch b&w I broke more off and used it for a planter, with topsoil etc. It had drainage of course so I had to be careful not to overwater. The plants did really well and I wondered if it was the phosphorus inside the screen that made the difference.
If you break more than the neck off, especially if it still has the vacuum, I think there is a little, very thin cloud of phosphor that gets dislodge from the blow, but maybe that was just what I expected and it didn't happen. Anyhow, I do this sort of thing outside and I give it time for the cloud to blow away.
And I don't touch the phosphors or I wear gloves.
I especially wanted to see what was in a color picture tube so last summer I broke one of them open. I already had a gun from another one, but this time I wanted the shadow mask. I wanted to see how they made it stay in one place (very important) while being bumped around. It was in their firmly with a very simple design. The shadow mask has to have the same curvve as the inside of screen so the distance from each set of 3 holes is the same. Otherwise, there are color fringes to images.
I do all this after the tube is removed from the set. I want the set light for throwing out, and I don't want to be working with broken glass in the set.
Then the whole picture tube goes in a big garbage can. The trash guys wear leather gloves anyhow, and they don't stick their faces in the trash.

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While you can get a good jolt immediately after shutting off the power on an old tv, espeicially those old tube sets, your fears are over rated. After you unplug it, let it sit during your dinner and it will be safe. Or leave it overnight to really feel secure. The biggest risk spot is the high voltage cable to the CRT (picture tube). Thats a thick wire with a rubber suction cup (looking) thing that is attached to the picture tube itself. If you want to work on the tv soon after unplugging it, just use unsulated plyers to yank that wire off the CRT, then touch the bare end (under suction cup) to the metal chassis. The capacitors terminals are under the chassis. Theres no need to stick your hand down there, but they discharge in minutes anyhow. Neither of these will kill you (with tv unplugged). It will just wake you up and make you say the f-word. It's about the same thing as touching a spark plug wire or electric cattle fence. So, relax.....
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One word of additional advice.....regarding the suggestion below to: "just use unsulated plyers to yank that wire off the CRT"...
The connection you are removing from the CRT is the so-called 2nd anode high voltage connection, and lies beneath a protective insulation 'rubber suction cup' placed there to prevent accidental contact. The actual connection is a spring loaded / springy, flexible contact which has been compressed before insertion into the tube receptacle.
"Yanking it off" adds the very real risk of breaking the glass envelope of the picture tube. The connector was not designed to be yanked, and moreover, the glass contact on the tube is also not designed to withstand very much force / tension. The correct removal technique is to compress the springy contact, causing its' "hooks" to retract", then gently removing it from the glass tube.
I hate to nit-pick other excellent advice such as was given below, but the risk of glass damage and the remote possibility of the CRT imploding are real issues, and perhaps as dangerous as the issue of a shock hazard. I felt I had to throw in my 2 cents.
Smarty
wrote:

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You are correct, I should have been a little more specific on that point. Actually, since this tv is going to the scrap heap except the wood cabinet, that wire could just be cut. Just leave the suction cup part on the CRT. Actually, if cut right at the chassis, take the plyers and touch that cable to the chassis to be sure the CRT is drained. The wire should be long enough if cut in this manner.
By the way, is this an old tube set? If it is, tubes are worth some money to antique rebuilders these days. More than likely most of them are still good. One bad one can kill a tv. I used to work on tvs when I was in my teens, and I saved all the tubes. I have boxes of them. Some day I plan to sell them and I may be sitting on a small fortune. So, if it is, save the tubes.

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On Tue, 25 Sep 2007 01:47:19 -0500, snipped-for-privacy@notmail.com wrote:

You got this right in your second post, but afaict, the sentence above his backwards. Once the wire is off the picture tube, it's not the wire that holds the voltage, it's the picture tube. It's one big capacitor.

I' ve been careful with the tv's off, but one time I was measuring something with the tv on, and my hand didn't slip afaik and I didn think I did anything wrong, but I guess I got about 2000 volts. I ended up on the other side of the room. I guess, because my legs extended, or because of fear. I wasn't hurt but it was scary.

That is, keep it from working. Not damage it.

I plan to sell mine too, but so far, I've asked a couple guys at hamfests who sell them, and they only want new in box tubes. I have all mine tested, on a quality tube tester, and have both ratings on the tubes in wax pencil (and of course, not only can one tube keep a set from working, but in many cases, the set will work even if one tube tests bad, so just having a tube of the right name can be valuable. In fact when tube heaters were in parallel, sometimes a tv would work fine with a tube completely missing. But don't count on that. :) I think they were other than the final amp, and the signal went around the tube socket through other parts.
Anyhow, the two guys I talked to weren't interested. Of course things can be different in other places, and things can change also.
Back in about 1976, my roommate said he was at the incinerator in Queens, NY and he saw loads of tubes lying in the sand there. I went out that night and got about 200, most of them still in the box, and almost all tested good. Plus I have about 200 I've added, minus the ones I've used.

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