Exploding TV — maybe the transformer

Salaam to thee, O Enlightened One! A while ago, a friend of mine, an interior decorator, was hired to redo a living room for a semiinvalid lady who was living alone. The drapes in the room had small holes ripped in them, and bits of debris were embedded in the walls. The owner explained that one evening she turned off her TV set, as usual, but this time the picture stayed on the screen. Frightened, she unplugged the set, but the picture remained. To compose herself, she left the room and settled down in her bedroom to read a while before going to bed. Then came the explosion. My friend tells me she thinks this woman is lucky to be alive. Are you aware of any incidents like this — M. Larson, San Diego

One at a time, yes. As a sort of package deal freak-out, no. Since I have this story thirdhand, I suspect there were some details garbled in the translation. The best my technosources can tell me without more data, there’s probably no connection between the ghostly image and the explosion. Yeah, I had a hard time believing it, too, but apparently the little old lady was just having a remarkably bad TV day.

I’m assuming the picture remaining on the TV screen was a still image, frozen at the moment she switched off the set. (If not, and she claims she was still receiving a moving image after unplugging the thing, well, the TV is the least of her troubles.) The picture we see is created by the selective zapping of the phosphor coating inside the TV picture tube. As the phosphor dots discharge their energy, they glow, producing a visible translation of the signal that entered the back of the TV. It’s apparently neither rare nor dangerous for a still image to be left on a TV screen when the set’s turned off, the result of a slow discharge of voltage from the TV tube.

Only a limited number of things in a TV will explode. One of the most likely is a burned-out transformer, maybe the flyback transformer, which puts out about 20,000 volts. The transformer’s similar to the ballast in a fluorescent light fixture, containing the same black goo that comes out when they blow. This might be part of the debris on the curtains and walls. Yes, the lady is lucky the exploding TV didn’t start a fire.

TV conflagrations in the U.S. are rare. But there was an epidemic in the Netherlands a few years ago — 200 blew up in one week — caused by a manufacturing defect. Warnings were issued in some parts of the Middle East during the Gulf War advising the public that watching CNN 24 hours a day, day after day, could overheat poorly ventilated televisions and cause them to catch on fire. And because exploding TVs in the former Soviet Union are so common (and programming so bad), the national joke is that the explosion is the most exciting thing about owning one. “Cheap parts” is the official explanation.