CurtPalme.com Home Theater Forum

antorsae · Joined: 16 Jul 2006 Posts: 297

Does somebody know what causes banding in a Marquee? I understand too much random green convergence correction causes it, but I would like to know the technical explanation as to why it is caused.

Anybody knows?

Tips to minimize it?

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

This is the mystery.... I dont even think TSE has figured out how to solve it but he may have the theory to why its caused.
But I know for one thing if you use no bow at all you have the best chance of no banding.
Also perfect magnetic set up helps. The less you have to converge the blue and red to green the better, and the best way for that is to have all three grids
magnetically lined up as best as possible. Also having the width coils on the HDM set so each grid width is equal will help with less convergence.

I have always did the magnetics as best as possible , then used the online guide for mechanical set up. After i do that i forgo the
geometry and go straight to convergence of all colors with no geometry. Then i do the convergence on Green(interpolated) trying to use no bow and checking a full white field every so often to make sure no banding has come up. It usually comes up for me when converging quadrant 1 if you split the grid into 4's with one at the top left as Q1. If you notice banding press the * key to go back and check the full field after each return. After your done here, go and touch up with random. Again checking full field but this time after each convergence, if banding comes move to a different area that needs convergence touch up and go back to the spot that banding was introduced, converge and check. if it keeps coming back then I scrap the whole thing by pressing 0 and do guided convergence instead of Interpolated. usually the interpolated and random work for me. its a long arduous process , but it helps.

Athanasios

Tim in Phoenix · Joined: 21 Oct 2006 Posts: 4409 Location: Phoenix

Hello

It is bunching and spreading of scan lines caused in the way the convergence system operates in zones. Terry and Gregor offer some tips how to minimize the problem: http://www.etechvideo.com/techtip10.htm

.

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

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

There must be something besides bow affecting it. I just tried ramping my BOW up & down. The banding definitely got worse as you got farther from 50, but even at 50 it's just noticeable on a white field. I tried ramping the vertical S & C LIN up & down and didn't notice any change from that.

Fortunately the banding is slight enough that I can ignore it -- I doubt anybody but me will notice it -- but it would be nice to get rid of it completely...

perisoft · Joined: 29 Aug 2007 Posts: 2920 Location: Ithaca, NY

I'm glad you Marquee guys are around... reminds me how much I love my Barco... Twisted Evil

**Curt Palme** · Posted: Mon May 11, 2009 2:12 pm Post subject:

Top and bottom pin usually does it. Ditto with interpolated green convergence adjustments.

I did an 8500 install this weekend, that showed none whatsoever at any point while converging. THe 9500LC shows some, but I minimized it by tweaking the top and bottom pin, center bow and then going back into the interpolated menu.

Peri, Barcos still have that line of coincidence that I get emailed about regularly.. Twisted Evil

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

So are you saying to un-do the top/bottom pin until the banding goes away, then use green geometry to correct for it, or...?

**Curt Palme** · Posted: Mon May 11, 2009 2:56 pm Post subject:

It's a combination thereof, seems to vary from set to set. Make sure you see no banding at a full initialization (if so, you have problems in the chassis or with the screen), then do a basic geometry setup in the geometry menu, then go to the all white (all green) screen to check for banding. If none is seen, then go to the interpolated green convergence, toggling back and forth between the crosshatch and all green screen to see if any adjustment adds banding. If so, then back off that setting a bit, and so on.

Continuous checking of the all green screen for banding will prevent you doing 2 hours of setup, only to have to start over...

jkruger · Joined: 24 Oct 2007 Posts: 2435 Location: Carlsbad, CA

**Curt Palme** · Posted: Mon May 11, 2009 3:49 pm Post subject:

Nope, same solution as the Marquee, keep checking for it while doing the geometry/setup.

WTS · Joined: 08 Mar 2006 Posts: 1276 Location: Calgary

Peri, Barcos still have that line of coincidence that I get emailed about regularly..

Curt, what is this you talked about, where is this line?

jkruger · Joined: 24 Oct 2007 Posts: 2435 Location: Carlsbad, CA

On my 1209s it's a vertical line right in the middle of the screen. I also have some vertical lines on the left side. None of them are really noticeable to anyone in the room but me.

joatmon · Joined: 17 Mar 2009 Posts: 127 Location: Ottawa, Ontario

May I ask a question? I am a newbie (I own a PJ but haven't set it up yet because my basement is a WIP)...

What is banding? Can someone show me a photo of what it looks like?

perisoft · Joined: 29 Aug 2007 Posts: 2920 Location: Ithaca, NY

**AnalogRocks** · Posted: Tue May 12, 2009 3:27 pm Post subject:

garyfritz · Joined: 08 Apr 2006 Posts: 12088 Location: Fort Collins, CO

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

my LCD monitor must suck cause I cant see the bands your trying to emulate.

Athanasios

perisoft · Joined: 29 Aug 2007 Posts: 2920 Location: Ithaca, NY

Heh, I think he changed it.

I guess it would really suck for a music lover to have that problem - they'd always be watching their two least-favorite bands...

*gets coat and heads for door*

WTS · Joined: 08 Mar 2006 Posts: 1276 Location: Calgary

Hi jkruger,

Is that a horizontal line you're talking about. I have seen that and by adjusting the geometry you can get rid of it. It seems the more bang on the goe is then the line shows up. I just offset a couple of the settings until it went away, that's not to say that I had to offset it where it was noticable though.

Perisoft,

As far as the convergence not being fine enough, I had that problem in a few areas of the screen so I just changed out a few resistor valves on the converg board to give me a finer step - problem solved.