And if so, what’s to be done about it? When it’s on, there’s a bright horizontal bar across the screen halfway down, and only the bottom half of the picture appears, from there down. The top half of the screen is black. It’s a 27" Mitsubishi that’s probably about 15 years old. Is it time to lay it to rest?
It’s almost certainly a bad vertical output stage component. Possibly, the vertical output transistor itself. It could be repaired, but these days, few technicians diagnose problems to the component level, and it might end up costing nearly as much as, or even more than, a new set. If it’s a very good set otehrwise, you could call around and see if any places will at least look at it for little or no cost, and give you an estimate before deciding.
Somebody who knows TV repair may be able to fix it but the labor cost may not be worth the end result.
It sounds like your TV has lost power to the top half of the yoke assembly.
In very basic terms the TV tube needs a magnetic field aroud part it to help aim the electrons to the screen. If part of the electro-magnet assembly loses power you get a section of your TV blank. This stuff is fairly high voltage so I wouldn’t recomend you exploring the inside of your TV to try and fix it.
Just ignore my reply. Q.E.D. usually does better at this than I do. 
We seem to agree that the cost of TV repair is usually not worth the effort.
Thanks to both of you. I took your advice and called a guy. He came, looked at it, said something about capacitors leaking (I think that was the expression), and carried it away saying something about $121, tomorrow. Doesn’t that sound good? It did to me!
Was the picture squished, and looking like a bad letterbox version? If so, it’s called vertical collapse. Hopefully it will come back good as new.
“Mother’s gone too far. She’s put cardboard over her half of the TV screen. We rented Man Without a Face- I didn’t even know he had a problem!”
It’s much less than the price of a new 27" set, to be sure. However, bear in mind that NTSC broadcasts in the US are scheduled to cease in less than a year, in 2006, at which point you’ll either need to purchase a settop receiver to watch HDTV broadcasts on your current NTSC set, or buy a new HDTV television. That, and the fact that your TV is 15 years old, means you probably ought to start shopping around. I expect HDTV-ready and HDTV-capable sets will drop in price once the switch happens and more people begin buying the new sets. I’ve been looking at them myself, and drooling. The picture really is awesome.
I get the gist of what you’re saying, though it’s the first I’ve heard of it (I don’t get out much). NTSC=??? in real words, please?
Oh, sorry. 
NTSC stands for National Television Standards Committee, which is the body responsible for setting televison and video signal standards here in the US. The NTSC format is the current standard for analong television transmission, but is set to be replace by HDTV (High Definition TV) next year. HDTV is a digital format, which will give a sharper, clearer picture without many of the interference problems that plague analog transmissions.
So now everyone will have to buy a new high-def TV?
Add that to the new blue laser DVD players I’ve started hearing about, and I’ll have to pay a few hundred dollars just to keep watching whan I’ve been watching!
Uh, hate to bust your ballon, but for about $45 more:
http://www.walmart.com/catalog/product.gsp?product_id=3312972&cat=136944&type=19&dept=3944&path=0%3A3944%3A172479%3A3996%3A179875
For the most part, TV’s, VCR’s and DVD’s are seldom worth the price of repair anymore. I think that is sad, but true.
Hopefully your repairman will also give you some kind of guarantee/warranty with his repair when he returns it.
Yes and no. If you want all the benefits of High Def, then yes, you’ll have to buy an HDTV set. If picture quality isn’t foremost, you’ll be able to use a settop converter box which looks a bit like a cable box. You’ll be able to receive the HDTV signals on your current NTSC set, but you won’t get the resolution or picture sharpness you will with an HDTV set. On the plus side, you’ll save hudreds of dollars.