Happened across a very nice tube TV left behind at a rental property today. Brought it home, and the picture is gorgeous -- on the bottom 75% of the screen.
Near the top, there's this line -- you can see a clearly delineated single line each of red, green, and blue when the screen is blank, and when there's a picture onscreen that section resembles the "pinch" effect in Photoshop, like everything is squeeze together around that line. And then the top portion of the screen is blank.
Had that problem with an old TV once; that was definitely a magnetism issue. So I suspect that may be the case here, too. On the other hand, this seems like a late-model enough TV that it should degauss every time it's powered on, and repeated cycling hasn't made a visible difference.
Most of the talk I've seen online about manual degaussing involves pictures with discoloration, though it's mentioned that picture distortion can occur as well. I haven't seen this exact symptom described in the material I've read, though. And there are other things that can fuck up a TV picture, like crossed wires -- which is why giving a TV a good whack really DOES fix picture issues sometimes. (Tried it; no luck. Don't want to whack it TOO hard. Saw a couple people suggest a rubber mallet; don't have one onhand.)
There are cheap Chinese degaussing coils on eBay; I'm tempted to throw down $10 for one of those and see what happens. Alternately, I could just try a refrigerator magnet -- consensus seems to be that this is a bad idea but also that if you're just going to get rid of the set anyway then it's not like you've got anything to lose (and anyway any damage done with a permanent magnet can be undone with a degaussing coil later, provided you don't actually get it close enough to the TV to actually start ripping components out).
Anyone have any experience with this stuff? This is pretty much the perfect TV for retro gaming -- 20", lightweight, flat screen, and it's even got component video. It beats the hell out of the 20" screen I've been using. Or it would, if I could fix the issue with the top of the screen.
Should I buy a cheap degaussing coil, start by trying with a refrigerator magnet and THEN decide whether I want to buy a cheap degaussing coil, or am I barking up the wrong tree entirely and could this be caused by something completely separate from fucking magnets?
The best guide I've found so far is at
repairfaq.org. If anyone knows of a better one I'd be interested in hearing about that too. (I've no intention of actually taking the thing apart. This is a sweet screen but not worth the hassle of disassembly or the risk of electrocution. And while I took a couple EE courses in college, that was a long time ago and I'm by no means an expert.)