Shimmering and screen replacement on a Sony KL-W9000 (long) - AVS Forum
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post #1 of 1 Old 02-01-2000, 09:34 PM - Thread Starter
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I received my KL-W9000 last December
and have been very happy with the unit. I
do not have any fog problems but do have
a bit of a color uniformity problem (a bit of
a red hotspot in the upper left of the
screen). Its fairly minor and you have to
look for the problem to see it. My guess is
that this may be an LCD panel orLCD lens
issue. A good cleaning might solve it.

One thing that has bothered me with the
unit to the point of doing something about
it has been the screen shimmering.I'm
using a Home Theater PC with a Creative
Labs Blaster TNT driving the display and
WinDVD to play movies. I enjoy DVD's
and regular TV on this unit to the point
where I'm very into the movie (many DVD's
look 3dimensional -- like looking through a
window) and then I see the screen
shimmer during a pan or bright scene and
it takes that 3dimensionality out. So this
past weekend I decided to mess around
with screen replacement. I did some
research online and looked at various
screen sites as well as retailers for info
and pricing on rear projection screens. I
found that DNP (http://www.dnp.dk) makes
the best in the world. They are also the
most expensive. The best price I could find
was about $625 shipped for a 72" high
gain, high contrast 4:3 ratio screen from
them. I would have to cut this to the
appropriate KL-W9000 screen size to
make it work. The drawback to this
approach was that I would be wasting a lot
of screen after cutting as well as potentiall
$625 if it didn't work out. Another option
was a new type of screen from The
Chicago Screen Works
(http://www.thescreenworks.com/New_Products/new_products.html).
This is a new one piece screen and looks
promising. They can custom manufacture
a screen for the KL-W900 and the price
was $600. I wasn't able to get samples
and due to the price, I decided it was a bit
risky. Both the DNP and Screen Works
screens have dot pitch sizes of about .25
mm (much lower than the .7 or so of the
KL-W9000) so this should improve the
image sharpness as well as shimmering..
Their focus distances are over 3 feet so
this would be a problem with the
KL-W9000. I took my screen off and
measured the distance from the lens to
mirror to screen to be about 28". Due to
the prices and risk, I decided to not go with
these options.

My third option was doing some research
on current HDTV rear projection screens. I
came across Mitsubishi and Pioneer.
Mitsubishi uses DNP screens for their
Wide Screen HDTV. I'm not sure what
Pioneer uses. Mitsubishis's screen is 55"
diagonal 16:9 ratio and has a dot pitch of
.52. I called up their parts department and
got pricing. Their lenticular portion was
$180 shipped and the fresnel lens part
was about $200 shipped. The Pioneer is
also .52 dot pitch but the price is about
$40 more than Mitsubishi for each screen
part. I decided to get the lenticular part
from Mitsubishi and cut it to KL-W9000
size. It was pretty low risk for the price. The
fresnel would not be as good a fit since the
focal length is longer on the Mitsubishi than
the KL-W9000. So what are the results you
may ask. Well.. success and failure.
Success on the shimmering side. The
shimmering was reduced to a much more
acceptable level ( a finer pitch screen will
probably do even better). The Mitsubishi
lenticular part also has a darker tint than
the KL-W9000 lenticular part so the black
levels and contrast were much better after I
installed it (much closer to a CRT than I
have ever seen on the KL-W9000). But
overall this excercise was a failure
because the Mitsubishi screen after it was
installed caused vertical rainbow and
banding effects on the screen. I tried all
sorts of experiments.. reversing the
screen, not using protective layer,
reversing the fresnel part but none of these
combinations removed the banding.
Moving the screen further or closer to the
mirror caused the bands to get bigger or
smaller so I'm guessing that this banding is
a result of some interaction with the fresnel
portion and the lenticular portion. I was
thinking that this may be an issue with the
LCD but the LCD is an on/off device and
not like a CRT so there is no frequency or
harmonic that may be causing this (I could
be wrong here). The banding turned out to
be more distracting than the shimmering. I
put the screen back with the original
KL-W9000 lenticular part and will have to
live with it for now. I'm trying to see if there
are any cheap fresnel lenses anywhere.
Maybe something from an old/broken
RPTV that can be cut to KL-W9000 size. If
I find something cheap, I'll give it another
shot. My guess is that it will be quite
difficult to find a fresnel lens with a small
focal length since most RPTV's are mich
bigger than the KL. If anyone knows of any
such parts that can help, I would
appreciate it. I would like to get this
Mitsubishi combination working since the
black levels were much better and the
shimmering was reduced so there is
definate benefit here and its definately
worth it for $180.

I guess one good thing about all this is that
a red spot/splotch that I had on the middle
right of the screen has disappeared. I
bought a can of compressed air and gave
the light assembly a good flushing after I
took the KL-W9000 apart. The light
assembly is not very tightly contained. Dust
can easily get into the system and cause
spots/splotches. The lenses/LCDs also
had a dusty film on them but that would
involve a lot more work to clean. This may
be the cause of the minor red hotspot I
have on the screen but I think the risk to
remedy that is more than I'm willing to deal
with (for now http://www.avsforum.com/ubb/smile.gif)

-- John
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