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>I'm wondering if other video projector users have had yellow spots 
>develop in their images over time.  We've particularly had problems 
>with Sony projectors, including two of the VPL-FE40 units in our SoS 
>installation and an older VPL-PX40 we took out of service a few 
>years ago because of the spots.  (We don't have experience with any 
>other brands, so I don't know if they have similar problems.)

I've seen it as a problem with LCD projectors, never with DLP 
projectors. We usually see it as a blue haze forming around the 
periphery of the projected image which eventually spreads across the 
entire image like a cataract (primarily with Viewsonic projectors 
(PJ1172, which are really rebranded hitachis)).

I have the unique case of being at higher altitude than most other 
people (we're about a mile above sea level) and I think the 
underlying issue is one of heat. At altitude, we just have less air 
to move around to cool off the projectors (and lower end projectors 
don't have a secret altitude setting in firmware). Every LCD 
projector I've used eventually has problems with the screen closest 
to the heat source in the projector. The problem is definitely 
compounded if the projectors are being used outside of the 
recommended angles and positioning of the manufacturer.

I've talked with Sony, Hitachi, and Panasonic reps and I've never had 
a consistent answer so the above is a bit of conjecture. But, for 
stuff that we're using in exhibits and where airflow may be a 
potential issue, we're using DLP projectors exclusively.

-bw.
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Bruce Wyman, Director of Technology
Denver Art Museum  /  100 W 14th Ave. Pkwy, Denver, CO 80204
office: 720.913.0159  /  fax: 720.913.0002
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