CurtPalme.com Home Theater Forum

[perisoft]

I've done a couple of run-throughs setting up my 808s, and since I've learned quite a bit I decided to reset to center and do it all again, and see how it comes out.

One thing I had noticed before but which didn't 'catch' for whatever reason is that all three rasters are far too large horizontally - there's barely any unused phosphor, and that only right at the center of the tube on each side. I can't find any electronic controls to change the raster size.

This makes centering the rasters difficult or impossible, and is also a Bad Thing in general if I understand Curt's primer correctly.

Do I need to take the hood off and do some pot tweaking to get the rasters down to size?

Would the oversized rasters have an effect on PQ, aside from the potential for tubal implosion were I to incorrectly set H-size/phase/blanking?

Thanks!

[Zebu Fellenz]

Welcome to the forum Perisoft,

My understanding is that the width of the raster is not important. All that matters is that you make good usage of the tubes with the active image area and the raster that falls of the edges of the tubes should be blanked out.

Erik

[Ile]

Your sources front and back porch settings determines how much there is unused raster before and after picture.
Too big porches decrease sharpness and stress horizontal deflection circuitry and too small cause "raster ringing".
If it's possible to adjust porches from your source, try little smaller settings.

Barco likes pretty big porches with high resolutions and if you decide to adjust rasters so small that those fit to face plate your picture is going to be very small. Do what Erik told...

If you are out of adjustment range for picture width, it can be adjusted from SMPS sub board.
http://www.curtpalme.com/Barco808_Layout6.shtm