[graveyard85]

Me and my brother just bought a BG800. Who intended to have this as a ceiling mounted front projector. together with the PJ we got a screen(SW:206 SH:154cm). Using the lens program from Barco we learned that the BG had to be mounted 292,7cm from the screen. But we cannot mount the BG in that position. It has to be mounted approximately 15cm further from the screen. My question i therefore. Can it be mounted 15cm further back , using the same screen size without damaging the tubes. If it is possible to shrink the image enough at all on the tubes to get it inside the screen. The lens program tells me that the phosphor will be reduced to 10,8 cm. Will that damage the tubes.


I hope someone can answer my questions. and help me solve this problem.


confused:



Best Regards


Graveyard85:

 

[mysphyt]

You can do this, but as you indicate you will use less of the phosphor area. This will have some negative impact on the picture brightness and resolution, but 15cm shouldn't matter too much. Long term, if you later move the projector closer and use the full raster area the new phosphor you will be using may be visible as areas of different brightness on the screen.

 

[DarrinLinders]

Sir,


As Chris mentioned, this is not a big difference; However, why give away perfectly usable phosphor if you don't have to? These units have great blanking capability, so you should be able to make use of a large part of the tube face by decreasing the throw distance below that recommended by the lens program (unless the previous user(s) have already used the phosphor in a smaller sized area to a point where the wear would be too apparent). If the position the projector must occupy is not negotiable, is it possible to mount the screen a bit closer? This is what I have done with my setup on a similarly sized screen, and it has resulted in a bright, sharp picture. I have mounted the screen closer than specs, and increased the size of the image to occupy nearly the full width of the tube face. I have done this, knowing that: The raster becomes a bit weird and non-linear as you approach the edge of the scan, so convergence is a bit less than perfect at the very edge (2cm) of the image left and right. AND I am protecting the sides of the tube by ensuring blanking is properly set for each memory to ensure the raster is NEVER painted onto the area outside of the tube face (allowing this to occur WILL result in premature tube failure, as the edge of the tube is not structurally engineered to cope with the heat of the electron stream bombarding it continuously).


Hope this helps!


Darrin