Old television danger?

[Me]

Danger! Danger, Will Rogers! Danger!

[bud--]

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.

[Jeff Wisnia]

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

[Oren]

Thanks to all for posting!

The rubber cap popped off the tube, so I shorted anything I thought would hold power (several times for my sake).

I have the unit gutted and the tube is in the truck ready for a dumpster run. I will break the back nipple off before I toss it in, but I am tempted hear to explosion....

-- Oren

"My doctor says I have a malformed public-duty gland and a natural deficiency in moral fiber, and that I am therefore excused from saving Universes."

[HeyBub]

NO!

The physics are that you will see an IMplosion.

The broken glass from one side will accelerate toward the center of the tube. By the time the shard moves the ten inches or so, it has reached super-sonic velocity and will keep going until it hits something. You, possibly.

You should have at least 1/8" of steel between you and a disintegrating picture tube.

[Oren]

Toss it into an empty construction dumpster - duck and listen :)

I can't shoot it with a shot gun!

I'll break the tube on the back as mentioned.

-- Oren

"If things get any worse, I'll have to ask you to stop helping me."

[Ralph Mowery]

If you go to the very back of the tube there will be a very small piece of glass. Take something like wire cutters and cut it off. If done correctly you will hear a lot of air rushing into the tube. Be sure to wear some heavy gloves,glasses/goggles and maybe even a coat. wrap the tube in a blanket. You probably will not need any of this, but it is best to be safe. I have cut off 3 tubes over the years and no problems. Also shot two that were still in the sets with a 22 rifle from about 30 feet. Impressive implosion.

[Oren]

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."

[alvinamorey]

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.....

[alvinamorey]

If there is still power in it after many years, let us all know. I'd like to patent that circuit and get wealthy from the eternal electrical storage cell !

[alvinamorey]

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 p*rn videos, and the CRT blew..... (You'll have to use your own imagination).

[Smarty]

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

[bud--]

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--

[Oren]

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..

[alvinamorey]

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.

[mm]

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.

>

[pheeh.zero]

This should be Will Robinson...to quote the robot!