CurtPalme.com Home Theater Forum

[9kids]

I have read a lot about how important it is to get the raster perfectly centered and maximized. I think I have done a pretty good job of centering and maximizing, but after doing the geometry I noticed that because of the effect of the Keystone adjustment (smaller width at bottom than at the top), that I could move the raster down some more and then increase the raster size even more. So before keystone adjustment I would have all four corners of the raster almost touching the corners of the tube, and after keystone the top corners are still almost touching, but the bottom corners far from the edges of the tube. So if I move the raster down, I can increase the size of the raster quite a bit more.

So my question is, is it more important to have the raster center top to bottom or is it ok to move it down and maximize the phosphor use. I am guessing it is probably better to keep it centered (seems like it might be easier on the electronics). I am guessing that during Guided Mechanical Setup, when you are moving the raster’s around on the tube face that it is actually the static convergence that you are using to move them.

Thanks

John (9kids)

[Nashou66]

I maximized phosphor usage on my 8000 just like you said and have no problems with anything, convergange wise or other heat issues on the electronics. you might get some banding(different shade across the screen) but some marquees will and others dont.

Athanasios

[Joust]

nothing is written in stone.
If you can, you can. its a matter of going through the setup and the going through it again.
you can go through it a 100 times and still make minor adjustments, i know someone that does that.
Your first time through will result in a usable image.
It all depends on how anal you are.

[draganm]

if your really using that much Keystone such that your raster is a big Trapezoid you might want to reconsider your set-up? If your shooting up from the floor at an angle to a 16:9 widescreen then the machine was never really designed to do that. It was made to sit either on a low table or hang from the ceiling. roughly, the bottom the machine whould be within 12" of the bottom of the screen for floor.

[Tim in Phoenix]

Guys!

The other key alignments include having the scan yokes level to the tube faces and each other; and to match raster heights and widths for the least load on the convergence section.

[deronmoped]

Suppose ably you want as little keystone as possible so the image uses a much tube face as possible, giving you the same resolution top to bottom. Also suppose ably you want the image projecting through the center of the lens to give you maximum resolution. It may be a trade off either way you go, the image will be not in the best spot no matter which way you go. Less keystone or centered on the lens, I have not seen anyone test which is better.

Deron.

[9kids]

[garyfritz]

Are you actually running a 4:3 raster? I generally center my raster with a 4:3 (because it's easier to see it's centered with a full-size raster), then I squeeze it down to a 16:9 raster for actual setup. And with 16:9 you can run it a bit larger because you don't run into the corners.

[igroucho]

On a Marquee with linearity controls you really should center the center of the #-hatch on the tubeface, not the edges of the raster to the edges of the tubeface. Done properly the raster will always stay centered even after adjusting linearity.
The main reason to having the center of the raster at the very center of the tubeface and not move it because it's possible due to keystone-geometrics is that the picture will always be at its sharpest at the center, due to properties of the optics and spot sharpness/shape, at which point the eye focusses and the action for the overwhelming part takes place.

[cmjohnson]

Check the PJ's point of aim as well. Use the slots down the side panels as a reference. They should point directly at the vertical
center of the screen. And your setup angle should be under 10 degrees, with (I think) an absolute max of 15 degrees as
that's all that the Scheimpflug and geometry are intended for.


Do your setup at 4:3 and then shrink vertically to 16:9 for viewing. (Unless you're viewing 4:3 content.) And as Gary noted, you can
get more width out of a 16:9 setup because the picture doesn't get into the corners of the lenses.

igroucho makes a good point. You CAN use the linearity adjustments (if equipped) to adjust crosshatch centering, but this may
negatively affect linearity.

But there is another way.

If you've got your mechanical, magnetic, and electronic centering as well set up as you possibly can make it, and the crosshatch still
isn't properly centered, you may need to adjust the master centering of the crosshatch via an option in the supersecret factory
service menus. I would avoid this unless you're SURE that you have to do that adjustment.

One final check I make is to ramp focus from one end to the other. The crosshatches should NOT move in relation to each other or
the screen. Focus should change, NOT position. If it does, it's not set up correctly.



CJ

[garyfritz]

Chris, that "ramp the focus" test only checks proper magnetic alignment, correct?

[Gino]

[igroucho]

[cmjohnson]