CurtPalme.com Home Theater Forum

Untuned · Joined: 03 Dec 2011 Posts: 93 Location: Pooler, GA

I'm going through the process of setting up my Runco-933. According to the setup manual for the NEC 6PG Xtra, the throw distance for a screen 80" wide should be 116". However, in order for me to fit the width of my projected image on the screen, the pj is something like 86" away! What gives? Is my raster too big? What am I missing? Also, is it normal not to be able to focus the blue as sharply as the green or red?

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Throw the throw distance calculator out the window and do the hands on way ! Wink

First maximize the raster on the Tube face leaving about 4-5 mm to the edge of the tube.

Once you have that done position your PJ in a floor mount position for now if you plan on celling mounting it.

Put up an grid pattern from the source you plan on using( EX blu ray player) and then move the PJ to a position where it
fills the screen .

Then you will have your position. If ceiling mounting transfer the measurements of the mounting holes to ceiling and that is where you will mount it.

But do geometry and centering of the patterns on the floor position.

There are some good guides, one is Guy Kuo's focus guide. I'll look for the link and post it here.

Blue should be a little de focused anyhow to get greyscale right .

Nashou

CasetheCorvetteman · Joined: 09 Nov 2008 Posts: 6326 Location: Australia

Youll probably want to leave abit more than 4 or 5 mm on an NEC... Id be going more like 7-10mm...

See what Macgyver and Curt say before you go that close, just to be sure...

**kal** · Posted: Sat Jan 14, 2012 2:15 pm Post subject:

+1 to what Nashou said.

Kal

Untuned · Joined: 03 Dec 2011 Posts: 93 Location: Pooler, GA

Wow, thanks for all the replies! I do intend to do a ceiling mount, but I'm doing the initial setup from the floor. I've read "Definitive CRT Projector Setup Guide", the article "CRT Projector Focus & Mechanical Aim" by Guy Kuo, and to keep confusion to a minimum, I've been following the "NEC PG Series Mechanical Setup Procedure". But really, 86" throw distance for an 80" wide image? That really buggers my intended ceiling mount in the family room...

After putting all the settings to zero, I thought the raster was pretty well centered. I thought it was wide, so I tried the amplitude setting to decrease it's width, but the change was so little, I put it back to neutral.

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

CRT's have a much shorter throw than Digitals. It is something many digital to Crt converts are surprised about.

Athanasios

**kal** · Posted: Sat Jan 14, 2012 7:42 pm Post subject:

You need to get the throw right otherwise you'll burn out the tubes much faster than intended because you have to crank the contrast to get the light output you want. Less tube surface area used means less brightness.

See here for an example of a poorly installed set (installed too far back): http://www.curtpalme.com/TubeCondition_PoorInstall.shtm

Kal

Untuned · Joined: 03 Dec 2011 Posts: 93 Location: Pooler, GA

Thanks Kal. I want to install it correctly, but the throw distance is quite off what the manual states. My raster is centered and it does not go off the tube face. Maybe once the convergence is done, the image will not be distorted and I'll be able to adjust the final distance. Any tricks for the astig adjustments???

**Curt Palme** · Posted: Sat Jan 14, 2012 8:01 pm Post subject:

Nashou66 · Joined: 12 Jan 2007 Posts: 16171 Location: West Seneca NY

Untuned · Joined: 03 Dec 2011 Posts: 93 Location: Pooler, GA

**kal** · Posted: Sun Jan 15, 2012 1:38 am Post subject:

Untuned · Joined: 03 Dec 2011 Posts: 93 Location: Pooler, GA

I think I spoke too soon on the throw distance. Since the geometry has not been corrected yet with blue being wide on it's opposite side, ditto for red, I thought things were way out of wack. Once I correct geometry, then I think the throw distance will make more sense.

I was reading the Guy Kuo document on mechanical set up, and he talks about Scheimpflug: is that what the lens rings are for? Do I need to do anything else for that?

Also, is there a simple and accurate way to square up the pj to the screen? It is not as simple as I thought it would be and obviously affects my adjustments. How far do I go setting up on the floor before I hang it on the ceiling in final position? The document on astig adjust was helpful for understanding which rings did what; I just have to do it now...

**Curt Palme** · Posted: Tue Jan 17, 2012 6:05 pm Post subject:

The lens types are on a sticker under the top cover. Should be HD-145s.

You really need to start on page 1 of the manual. It sounds like you're jumping around, and are jumping to conclusions. Guaranteed that will result in a mess. (no offense). Start on page 1 of the manual, and work through it. If you get stuck, then post as you go along. The manual covers the lens rings, and everything you need to know, and it's written in the order that you need to do it. If you jump around, you'll miss a crucial step, and you'll end up frustrated.

Untuned · Joined: 03 Dec 2011 Posts: 93 Location: Pooler, GA

Ok Curt, no offense taken. I did start at the beginning of "Mechanical Setup Procedure" for the Nec PG series, but I also read "The definitive CRT projector setup guide" and "Focus and Mechanical aim basics" (Guy Kuo write-up). It was Mr Kuo's discussion on Scheimpflug that caught my attention since it did not appear to be emphasized in the procedure I was following. I did not realize that was what the rings were for. Anyway, I started at page 1, and I got stuck at the astigmat part, and that's where I'm at still.

About optical focus: I understand that the blue should be slightly out of focus, for reasons I do not full understand, but Mr Kuo says that blue optical focus should be accurate, it's the electronic focus that should be a little out. Notwithstanding, with the cross-hair pattern, I cannot get the blue line as sharp as the green or red: the line always stays fatter and looks slightly fuzzy. Is that normal?

**Curt Palme** · Posted: Wed Jan 18, 2012 5:30 pm Post subject:

What he means is that optically, the blue tube is no different than the R and G. Same lenses, etc. So optically your focusing ability should be the same, but the blue will appear to be a bit less focused due to the phosphor and nature of the blue tube itself. If you can't see a halo sticking out of the edges of the R and G image, caused by the blue tube, I think you're fine.

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

Untuned · Joined: 03 Dec 2011 Posts: 93 Location: Pooler, GA

Draganm: I would say that is what my tube face looks like except my raster sides look closer to the tube edges. The gap between image and raster is very small top and bottom, and much wider on the sides.

When I am adjusting geometry, do I use the amplitude control to ensure that the grid pattern shows squares and not rectangles? Or do I just verify that the height vs width ratio is correct? It seems like a strange question, but I have a 4:3 screen (that came with the pj) but I am setting up for widescreen material.

draganm · Joined: 08 Mar 2006 Posts: 8990 Location: Colorado

Untuned · Joined: 03 Dec 2011 Posts: 93 Location: Pooler, GA

I actually picked up a DVDO Iscan HD. I needed to convert to the VGA output, and I thought it was a good idea until I realized I'd have trouble with the HDCP bit. Theoretically, my Blu-ray player will put out 720p and 1080i via component with a blu-ray disc (as long as nothing is plugged into the HDMI port). Supposedly the iscan will passthrough to the vga out. Anything that is not high-def will leave the player as 480p and be upconverted by the iscan to 1080i. In theory...At least having a constant output sounds like a good idea.