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Posted: 8/30/2004 7:13:20 AM EST
I posted this in a big-screen TV thread here and it got lost... I'm going to post it here as a quote and see if anyone knows anything about this...

Thanks in advance.


I have a Toshiba 35" TV. It's been good for movies, nice and sharp, and it has component inputs for a great picture... but when I watch my most beloved sport, hockey, two of the networks I watch it on (ABC being the worst culprit, FOXsports almost as bad, and that's where the majority of the games are) the picture of the ice is so bright that it causes a brownish "bruise" call it on the lower right quadrant of the screen - and if I don't change the channel or adjust the brightness, it progresses to purple. I HATE this-- I have looked it up online and the best I can come up with is to either 1: always turn the TV on from the set itself (not the remote) so it "degausses" the screen (this may or may not help I've discovered) or 2: buy a degaussing rig and do it manually (but there is no guarantee it will help for the life of the set).

Any ideas? TIA.



jim
Link Posted: 8/30/2004 7:14:51 AM EST
get a new TV
Link Posted: 8/30/2004 7:17:53 AM EST
probably has a speaker near the screen
Link Posted: 8/30/2004 7:26:56 AM EST

Originally Posted By NoVaGator:
probably has a speaker near the screen



That it does... I have a 5.1 surround sound rig going and the speakers are to the immediate left and right of the entertainment unit... Think this would make the white go to brown/purple? (heck, I should just unplug it and move it to test...)

Think it's permanent?

As to a new TV, this one was probably $5-600 and only purchased like 4 years ago... so not worth it to just get rid of it... but I'm looking into a new bigscreen TV sometime in the next year or so. If it's caused by the speaker I guess I'll ensure they're always a few feet away from the TV set no matter what set it's near.

Good thing there's a World Cup hockey game on tonight for me to test it out on!

Thanks.
Link Posted: 8/30/2004 7:28:57 AM EST
I had a similiar issue with a Toshiba 32".

The top right of the screen would turn yellow when the screen was a white or another bright color.

My solution was to give it away and buy a Sony.
Link Posted: 8/30/2004 8:03:16 AM EST
This is a problem with large screen TV's. They call it a purity problem. It can be caused by: internal/external poorly shielded speakers, steel beam in the wall, even the orientation of the TV itself to the earth's magnetic field, (I know that sounds like BS, but I've seen it). It usually can be fixed by a competent TV guy adjusting the set or taping small magnets to the picture tube. If moving the speaker or degaussing doesn't fix it, find a good TV guy and watch him, and see if he uses the magnet trick. FWIW
Link Posted: 8/30/2004 8:05:55 AM EST
def could be a speaker- MUST have shielded speakers on or near CRT tv's
Link Posted: 8/30/2004 8:19:01 AM EST
I've got an old 35" Mitusbishi TV that has lousy voltage regulation. On "hot white" parts of scenes the image will bloom and instead of white, the area will be exactly as you describe: "a bruise".

However, the fact that you indicate that it turns purple leads me to think that it's your speakers, that you have a localized magnetic disturbance. Has it always been like this from day one or did it just now start?
Link Posted: 8/30/2004 8:22:50 AM EST
Removing the speaker will fix the problem, but it may take a few days for it to get back to normal. The speaker's magnet may have magnatized part of the tube
Link Posted: 8/30/2004 8:27:32 AM EST

Originally Posted By Airwolf:
I've got an old 35" Mitusbishi TV that has lousy voltage regulation. On "hot white" parts of scenes the image will bloom and instead of white, the area will be exactly as you describe: "a bruise".

However, the fact that you indicate that it turns purple leads me to think that it's your speakers, that you have a localized magnetic disturbance. Has it always been like this from day one or did it just now start?



Well, I got the TV during early summer from Best Buy (gack). I set up the speakers a while after that... and didn't notice anything until hockey season. I wound up coming up with a special brightness/contrast/color adjusted preset and just changed it when I watched a game (frequently: it's my favorite sport). On some of the brighter telecasts (the aforementioned ABC) it would "bruise" even with the brightness turned down...

So long story short, it's always been like this and I just messed with the constrast stuff to "fix" it. Now when I go home tonight I'm going to move the speakers away and see if that was the culprit (and keep them away for a while, thanks NoVaGator)

jim
Link Posted: 8/30/2004 8:49:18 AM EST
Link Posted: 8/30/2004 10:38:37 AM EST
Link Posted: 8/30/2004 10:46:25 AM EST
Use an un shielded audio speaker (at least 75 watts) and move it around your brown spot. See if that clears it. Bookshelf speakers work well. I take no repsonsibility if this doesnt werk or worse!
Link Posted: 8/30/2004 10:50:03 AM EST
Ha, I'm just going to move my speakers away, clean the screen, and hopefully in a bit it will go away...

Troy, I have the Avia disc now... Is the one you suggested better? (I don't expect a response, it's more rhetorical than anything)... The Avia settings wound up being kind of strange. The contrast for the TV was too high, and too dark for daily TV viewing. However, it really helped with the setup of the 5.1 components.
Link Posted: 8/30/2004 2:33:31 PM EST
get a bulk tape demagnatizer (about $20 from radio shack, if they still have them) and de-gaus your screen.
Link Posted: 8/30/2004 2:50:34 PM EST
Ok, I only perused the thread, but I will say this. Moving the speaker may not eliminate the result of having the speaker close. Newer TVs(and monitors) will 'auto degauss' when turned on. If the bruise stays after moving the speaker and turning the TV on and off(give it a few seconds or more before turning it back on) a few times, you may need a profession degauss. I was taught how years ago and I saw the results of a pro. I also saw the results that my uncle(Maytag repair man, no, really) had on his TV when he tried 'fixing' his. My advice, if you are gonna try to do it yourself, get(rent) a real degaussing tool. It is a plastic loop that sort of resembles a 'fish tape'. The right tool for the job.


ByteTheBullet (-:
Link Posted: 8/30/2004 3:45:11 PM EST

Originally Posted By cmjohnson:
If the bruise comes and goes, TURN YOUR CONTRAST SETTING DOWN.

What's happening is that full white images draw maximum current and it heats up the internal
component of the picture tube known as a shadow mask, or an aperture grille if it's a Trinitron tube.
This heating causes it to expand slightly, and that causes the electron beam that passes through its millions of tiny holes (or slots) to land partly on the wrong color phosphor.


Your brightness and contrast settings should really never be much above half way. Damage to the picture tube can result.

The shadow mask or aperture grille could be physically misaligned, too. No cure for that but a new tube.

Magnetic distortion is a possibility, too, but trying to manually iron out the bruise with a magnet in your hand is not something you should try. I can do it, but I'm experienced. First, things first...move speakers away from the TV set (and anything else that might be magnetic) and see what happens.


CJ



+1 He knows of what he speaks.
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