CurtPalme.com Home Theater Forum

Cube · Joined: 06 Dec 2009 Posts: 77 Location: IL, USA

At the top of my 1272's projected raster there's a strange white scanline. It appears on everything, even the internal test patterns, and blanking won't get rid of it. I mean, I can try lowering the top blanking area but the line just stays there. It's just above the black AKB line (which thankfully doesn't show up), right at the very edge of the raster. What is this? Is there any way to get rid of it?

Here are photos looking into the green lens. For another example check out this guy's post.

Jeremy112 · Joined: 28 Sep 2006 Posts: 2649 Location: Fond du Lac, WI

My old 1272Q had the identical scan line, use the blanking to hide it once the projector is setup, you wont see it then.

Cube · Joined: 06 Dec 2009 Posts: 77 Location: IL, USA

I tried that already... the blanking doesn't make it go away. If I advance the top blanking area down the screen it starts covering the video but the white scanline at the top is still there glaring at me.

I'm going to try messing with the V-Shift thing later and see if that does anything.

ecrabb · Posted: Thu Aug 12, 2010 9:43 pm Post subject:

That's the AKB line (or ABG as some call it).

You have two options:
1. Turn off AKB and deal with the G2/brightness issues that result manually, or...
2. When you do geometry, set it up with the test pattern a fair bit larger than what you'll want for your actual image area, then use RGB SIZE to make the active image smaller (moving the active image away from the AKB line).

I went with 1 on my G70, but 2 on my 12xx. On my 16:9 screen, I could get the AKB line to fall on the black wall behind my screen where it was just barely visible, and then only during full fades to black.

Also, on a 12xx, once your happy with your physical setup, you can always just mask off the offending part of the CRT so the line doesn't show up on the screen/wall - call it "manual blanking".

SC

Zebu Fellenz · Joined: 21 Dec 2006 Posts: 2567

It doesn't look like it's in the image area and the 1272 is an AC machine, I would take masking tape to the tubes and mask it off.

Erik

Cube · Joined: 06 Dec 2009 Posts: 77 Location: IL, USA

Oh, so that's the AKB line. There's a dark line I can RGB Shift the image through and that's what I thought the AKB line was for some reason.

I would go with the masking tape option but I'm using a 4:3 screen with variable aspect ratios. I could just avoid using 4:3 content on the pj or let it be stretched out I guess, but I'd rather just live with the line if it comes to that. Or I could go with AKB off but it seems like more trouble than it's worth (since you have to get at those touchy knobs whenever the black level needs adjusting...).

Here's another idea. When I'm projecting 4:3 the line falls off the edge of the screen and you can't really see it on the wall, so that's no big deal. For widescreen projection I could add a moveable black curtain type of thing (like a window dressing) to the top of the screen for the line to fall on.

ecrabb · Posted: Fri Aug 13, 2010 5:42 am Post subject:

blange · Joined: 12 Aug 2010 Posts: 16 Location: Germany

I do have the same line(s) on my 1271. Mine were at the top and left of the image, before setting up the projector. Now, with a good setup and the help of blanking horizontally and vertically, the lines are gone. So i think, when you're setting up the projector properly, they should go, too. Do you have experimented with the move/shift button or changed the input signal?

As i already said, for me the lines have gone after the setup.

Cube · Joined: 06 Dec 2009 Posts: 77 Location: IL, USA

The AKB line can't be removed with blanking. However, it's not very noticeable after gamma adjustment and turning down the contrast. I'm happy with my setup now.

CIR Engineering · Posted: Fri Aug 27, 2010 11:01 pm Post subject:

Masking

https://www.curtpalme.com/forum_archived/viewtopic.php@t=21688.html

craigr