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Discussion Starter · #1 ·
I've noticed more and more that when I put a 1080i source into my TW56x81, the image seems to vibrate slightly. This is particularly noticeable when I bring up a menu text or even in the service convergence grid.


Is this just a symptom of the higher output of the crt's to put out 1080i? Should I be worried? The vibrating isn't really noticeable when watching program material.
 

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I have noticed the same thing on mine ever since I have had it. I bought mine in Feb 2000.


It hasn't seemed to have caused any problems and like you said, it is not noticable while watching programming.


Scott
 

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I have a TW40X81 and the effect is very pronounced when I bring up the convergence grid. I have not noticed anything when I have a real program source. I had thought it might be a power supply problem.
 

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Quote:
I have a TW40X81 and the effect is very pronounced when I bring up the convergence grid
Same here. But 1080i image looks stable when watching actual HD programs.
 

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I had the same / similar problem - when i'd pull up the menu in certain modes / with certain source signals, the menu would "shake" / "tremble" / "vibrate" (pick one). I had the set (65H80) serviced, and now it looks like it's gone. So a service call might be in order. I'm "glad" to hear others have the problem too - justifies my complaining about it to the techs http://www.avsforum.com/ubb/smile.gif


Good luck getting it fixed


Gertjan
 

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Discussion Starter · #6 ·
I'm not thrilled about having a service call, since my previous experience with my local technician is that he'll do more harm than good. The only reason I'm likely to call for service anymore is if the thing simply doesn't work at all.


Seems like it's affected other sets, not just mine (and h80's as well as x81's), and doesn't really cause a problem with PQ. Any technicians out there have a suggestion? If I can tell the tech where to look, that would be helpful.


Do you recall what they did to your set to fix this problem? (I already had a flyback transformer and green crt replaced)
 

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OK - I'll bite. I'm surprised no one has answered this one.


The "vibrating"/"shimmering" is normal - there is nothing wrong with your set. It's an artifact of interlacing, the "i" in 1080i.


I hope I'm not telling you something you already know, but here goes:


Interlaced displays (like NTSC, PAL, or SECAM televisions, or older color computer monitors like CGA or composite monitors for old Apple II or Commmodore computers) use interlacing to increase the apparent vertical resolution of the display by having the electron gun (the cathode ray of Cathode Ray Tube) trace out every other horizontal line of picture information on each pass. For NTSC (with 480 lines of picture information), the odd(?) numbered lines are painted first, then the even numbered lines are painted on the next pass.


It's very noticeable on any horizontal edges on the screen, especially menues and text, like sports scores, channel logos, or tickers. On normal video images, especially those with lots of movement, it's not a problem. Except, of course, football or basketball with the score in a corner of the screen and tickers at the bottom for scores of other games!


Two phenomenon trick the eye into combining the two passes, or fields in video lingo, into a single image - or frame.


The image information on the retina takes a bit of time to "decay". This is called Persistance of Vision. This is why 24 frames per second of film (or 30 fps of TV) appear to be continuous motion instead of individual still pictures. Or why those stick drawings on successive pages of a pad of paper appear to run across the page!


The second phenomenon is phosphor decay in a CRT, though it's less noticeable, especially in today's progressive scan monitors. When the electrons strike the phosphor on the CRT face, it takes a bit of time to decay. So when the gun makes the second pass to fill in every other line of the picture, the pixels excited by the first pass are still glowing, although somewhat less dim than freshly lit phosphors. This trick was used in the early days of computer monitors. Long-persistance phosphors were used to make the flicker less noticeable, which was fine for text displays. But when GUI's with video images came on the seen, it tended to make moving images blurry or ghosted (like trails on you mouse cursor in Windows...).


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[This message has been edited by jonlgauthier (edited 08-01-2001).]


[This message has been edited by jonlgauthier (edited 08-01-2001).]
 

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Thanks for taking the time to post such an extensive explanation, Jon. However, this is not what i was talking about. My menu would really shake up and down, not just "shimmer" from interlacing. The shaking also was irregular.


From what i was told, the entire guts (meaning all electronics excluding the CRTs) of my TV was replaced, so i couldn't tell you which part was responsible for it. (There were several other problems with my set that they probably couldn't pinpoint, and i guess they did not want end up having to go back and forth many times between the shop and my house replacing a part at a time.)


Cheeers,

Gertjan
 

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The problem here is definitely not due to interlacing. There is definitely some mechanical vibration that is causing the convergence grid to move up and down. I see it happen every now and then when I enter the convergence menu.

Also, the other day I tripped close to the set and ending up kicking it slightly. When I turned on the set the convergence was just way, way off.

On the convergence issue, how often do people converge their sets? I usually have to fine tune the convergence everytime I change aspect ratios. Changing one usually affects the other. This is a little annoying!
 

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Discussion Starter · #11 ·
I did full convergence and geometry workups with the templates just to get everything where it ought to be.


Now, I touch up convergence about once a month, and usually it's not that bad at all.
 
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