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How do I reduce the "halo effect" and glaring on my TV?


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9 replies to this topic

#1 of 10 OFFLINE   Dave H

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Posted September 08 2001 - 05:21 PM

I own a year and a half old Sony KP-61V80 (61") TV. While my picture is good, I notice a halo effect in dark scenes of DVD movies. Even more distracting is the glare lines that come from smaller brighter objects in dark scenes. Does this make sense? They are almost like light rays being omitted from bighter objects.

What can I do to reduce these? My TV has been carefully adjusted with Avia. Is an ISF the answer?

#2 of 10 OFFLINE   Guy Kuo

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Posted September 08 2001 - 06:22 PM

Probably the two most likely things to help your situation are to clean the optics and line the interior of your RPTV. Both of these require removing the front screen and may void the warranty if that is an issue.

The following information is applied only at your own risk. It's best to have someone who has done this type of thing before help. You should be cautious and must take care to avoid damaging your display or injuring yourself. There are dangerous voltages inside and the optics are easily scratched.

Removing a RPTV front screen usually requires removal of the front speaker grill and then the screen fastening bolts holding the bottom of the screen. Then the screen swings out slightly and is lifted off its mounting hooks which secure the top of the screen to the cabinet. Careful, sometimes there may be wires attached between the screen and the cabinet.

Once opened, inspect the mirror and lenses with a flashlight. An RPTV can attract a surprising amount of dust and grime. This scatters light and creates a hazy or haloed image. I don't smoke, but even so I needed to clean my lenses about every 6 months. A CRT is basically a big high voltage dust collector. The attached optics share in the bounty.

The lenses and mirror are very fragile and easy to damage during cleaning. Front surface mylar mirrors should NEVER be sprayed or wiped down as they will probably be damaged. Use a soft, clean brush to lightly waft off dust on such a mirror, but do NOT use any liquid cleaners on a mylar mirror.

A camera lens dust blower should be used first on the lenses. That removes some of the dust. Canned air is okay if it has been dehumidified. Do NOT use compressed gas cleaners which are not air. If you spray them improperly, the liquid may come before it has a chance to vaporize. If the propellant hits the lens in liquid form, it will mar the lens surface.

Once as much dust is removed as possible, see if a very gentle wipe of a fresh microfiber lens cleaning cloth will do the trick. Use a virgin portion of the cloth with each pass. Remember, once scratched, the lens will never be quite the same again.

If a microfiber cloth is insufficient to clean the lens, then resort to a cleaning liquid. Stay away from ammonia containing glass cleaners as they can strip away a lens antiglare coating. I like Lens Crafter's lens cleaning solution as it does not dissolve antiglare coatings. Their lens cleaning tissue is also lint free and less prone to scratch a lens. It is best to spray the liquid onto your lens cleaning tissue rather than directly on the lens. Otherwise, you risk excess fluid going inside the lens assembly. Use lots and lots of tissues so every stroke is with a clean section of wadded tissue. I prefer to start and lens center and work outward. During the stroke, I roll my hand so the soiled portion of the tissue is lifted off the lens surface. This reduces the amount of grinding that the grit does to a lens and also brings a dry portion of the tissue into contact with the cleaned area to wipe it dry. If you don't end up with a pile of used lens tissues, you probably are not changing tissues often enough. Seems wasteful, but so are scratched up lenses.

The last note to know about lens cleaning is that you should expect cleaning to eventually scratch a lens. That is why it must be done very carefully and only when necessary. If just dusting with a blower is enough, don't wipe down the lens.

Sometimes the concave lens at the bottom of the lens assembly is coated with dust. That necessitates removing the lens for cleaning, but doing that almost always means your convergence will be thrown off so I don't recommend that be done unless one is willing to reconverge a display.


Regular tissue paper is NOT a suitable cleaning paper unless you like lint and scratches. Use a CLEAN microfiber cloth to wipe the lens very gently.

------------------
Guy Kuo
www.ovationsw.com
Ovation Software, the Home of AVIA DVD
Guy Kuo
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#3 of 10 OFFLINE   Dave H

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Posted September 09 2001 - 10:33 AM

Thanks for the info., Guy. I am seriously thinking of going out and getting the materials to do this. How much would it cost to have someone come in and do it?

#4 of 10 OFFLINE   Dave H

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Posted September 10 2001 - 03:38 PM

Guy,

I bought some materials and took a look at the inside of my TV. I opened it from the back of the TV - not wanting to try taking off the front or screen. Using a flash light, I was pleasantly surprised to see there was little dust on the lenses. I did take the microfiber cloth to remove the little that was there. Taking a look up at the mirror - again, little dust was there. I didn't even try removing it because of the sensitivity of the mirror coating. I tried taking a hair dryer (on colder temp) to remove what little was there, but it didn't seem to matter - the little particles didn't leave. But, as stated, little dust on the mirror.

Unfortunately, the result of cleaning the lenses was negligible.

What next?

Thanks

[Edited last by Dave H on September 10, 2001 at 10:40 PM]

#5 of 10 OFFLINE   Guy Kuo

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Posted September 10 2001 - 04:12 PM

Were you able to look inside the lenses or just the upper surface? The deepest element of the system may be dirty, but if the top element is clean, the bottom is probably in good shape. The less cleaning you do the better if it isn't dirty with flashlight inspection.

The next maneuver is coating the interior of the lightbox with Duvetyne. You should be able to find some info with a search on this forum. I'm afraid that will be more than you want to do.

One thing I didn't think about is whether or not this is a focus issue rather than an optical halo problem. Tough to differentiate unless you already know what each looks like.
Guy Kuo
Director - Imaging Science Foundation Research Lab

#6 of 10 OFFLINE   Dave H

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Posted September 15 2001 - 08:37 PM

Guy,

What do you recommend I do? Should I call someone out? I know my TV is still under warranty - I don't know if this could be covered? It is getting a bit distracting.

Thanks,

#7 of 10 OFFLINE   Dave H

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Posted September 17 2001 - 09:10 AM

Come on guys....

I need some advice! Someone must have experienced this problem before.

#8 of 10 OFFLINE   Guy Kuo

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Posted September 17 2001 - 11:13 AM

Dave, it really does look like you've reached the limit of what would be prudent for your technical level. I think it would be best to have someone come out and examine the set. A normal service technician may be helpful, better yet would be a service technician who is also ISF certified - an unfortunately difficult combination to find.

There is a laundry list of items to check....

a. Optical clarity.
b. Optical focus
c. Beam focus
d. Beam astigmation
e. CRT cutoff function
f. Video amplifier function
g. Light box scatter reduction

I'm hesitant to have you go down these roads by yourself. An experience hand is probably the most prudent thing to obtain.

------------------
Guy Kuo
www.ovationsw.com
Ovation Software, the Home of AVIA DVD
Guy Kuo
Director - Imaging Science Foundation Research Lab

#9 of 10 OFFLINE   Dave H

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Posted September 17 2001 - 12:38 PM

Thanks, Guy.

Anyone out there know a good technican in the Detroit, MI area?

#10 of 10 OFFLINE   Guy Kuo

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Posted September 17 2001 - 08:51 PM

You might try Jeff at jbryngelson@bignet.net

If he doesn't work on your model display, he may be able to point you to someone reliable in the area.

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Guy Kuo
www.ovationsw.com
Ovation Software, the Home of AVIA DVD
Guy Kuo
Director - Imaging Science Foundation Research Lab




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