CurtPalme.com Home Theater Forum

gnnash · Joined: 10 Jul 2013 Posts: 216 Location: Lake Elmo, MN

I'm having an issue on my DTV-1100 where there is a horizontal line roughly across the middle of the screen with a sudden brightness shift, I think this may be banding? I tried to capture it as best as I can with my cell phone (admittedly not very well, but hopefully you get the idea).

The line is visible in all colors, but most apparent in green, and worst on the right. It is NOT burn, the line moves with the raster when I shift the raster around. I am aware I have some major (and small) 4:3 wear in there as well, I hope to try leveling it out a bit, although I wanted to fix this issue first, so I don't burn in the banding pattern.

I've tried changing linearity and vertical size as far as they will go without spilling off the tube face, and the banding persists, though it moves around with linearity as one would expect. Source is a Lumagen HDQ, and using a laptop directly as a source results in the same issue. Again, the line does move with raster shift. It is visible at any range of resolutions, from 480p to 1080p.

Any thoughts on what this could be? I do not see the issue at all during the all white warm-up screen, but there aren't any other all-white built-in test patterns that I know of that I could try. The issue is very apparent in an all-white screen, as well as blue skies in movie material.

Thanks in advance for any suggestions!

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

I cant see it, but are you sure its banding and not noise?

ElTopo · Joined: 07 Nov 2006 Posts: 1640

When you're using a ceiling setup you should be good and the line is not visible.

Unfortunately the floor setup gave me the same result in the past. It seems to be a common Barco issue.

You can try what is written here:

http://www.avforums.com/threads/barco-faq.757690/

Section:
Q: I have an odd horizontal line visible at times, what is it?

cheers

opv · Joined: 18 May 2010 Posts: 202 Location: Emek Hefer,Israel

It's called "Line of coincidence", a known Barco issue.
The line usually appears when you're driving the geometry setting to high (when the projector isn't mounted perfectly).
You can read more here:
http://www.avsforum.com/t/677762/barco-1209s-thin-dark-scan-line-cause-fix

gnnash · Joined: 10 Jul 2013 Posts: 216 Location: Lake Elmo, MN

Thanks all for the insight. I was under the impression that the line of coincidence was a 2-3 scanline-thick horizontal line, not a sudden change in brightness between the top and bottom of the image like I am seeing here.

Hopefully if I get a chance tonight, I can set all of my geometry settings to 49 one at a time, and see when/if the issue goes away.

I know I do have a slightly askew red deflection coil that I haven't straightened out yet, but I only really had to adjust the red skew any significant amount, not the green... There is some amount of keystoning going on due to the floor setup though.

fragzero · Joined: 30 Aug 2012 Posts: 344

In my experience with a 808s and 1208s it's a combination of geometry and convergence. Straightening the deflection coil and readjusting convergence might fix the problem!

**Curt Palme** · Posted: Thu Jan 09, 2014 3:11 pm Post subject:

Do a 'set to midposition' in the service menu and see if it goes away. (or pull the convergence tray out). If so, it's the line of coincidence.

gnnash · Joined: 10 Jul 2013 Posts: 216 Location: Lake Elmo, MN

opv · Joined: 18 May 2010 Posts: 202 Location: Emek Hefer,Israel

You can set all the projector into midposition in the service menu and you can undo the operation. you don't need to pull out the convergence tray for that.

gnnash · Joined: 10 Jul 2013 Posts: 216 Location: Lake Elmo, MN

As usual, you guys hit it right on the head. Resetting to midpoints eliminated the problem immediately, and a bit of trial and error showed that backing my top keystone up to 49 eliminated it as well. Looks like I have some more work to do with my mechanical setup! Good thing it's still on the ground...