BARCO Graphics 800 Convergence Problem on Higher Resolutions

DolbySR · 21-07-2009, 1:17 PM

Hello,

I have a Barco Graphics 800 installed in my Home Cinema and when it is fed with normal S-Video Signals, it works perfect but when I upgraded my Videosystem today with a Scaler and a Circuit to convert RGBHV into RGBS, I noticed, that I could not get the red and blue pictures into correct convergence. It only happens when I provide a 720p or 1080p picture over RGBS, with normal 480 it is no problem. Something I noticed as well was, when I try to center the images on the tubes, green works great, red and bluw on the other hand are always at the end of setting range...not normal, eh?
I attached some images below, perhaps one of you can tell me, where to start searching? I really would appreciate that!!!
BTW, I am an electrotechnical engineer, so I could do some measurements or things like that without any problem ;-)

damien55 · 21-07-2009, 2:19 PM

I would use RGBHV at this kind of frequencies.
Last time I tried RGBS I had similar problems with my HTPC.

Damien

DolbySR · 21-07-2009, 2:23 PM

Hello Damien,

Thank you for your reply.
You had similar problems like me? Well, for RGBHV, how can I connect my scaler to my Barco using RGBHV? Using Input 5 over BNCs won't work because it cannot sync to it. Or can I use Port 3 for that? It is a normal scaler which provides VGA Output, well yea, RGBHV Format. Or is there a Sync Converter Circuit anywhere which adapts RGBHV to this negative Sync required by Barco?

damien55 · 21-07-2009, 3:19 PM

I'm not an expert but I think that having seperate syncs would give less problems if you can get it.

What is the name of your scaler. Maybe it is possible to get a negative sync from your scaler to make your BG800 happy. I think that port 3 will not work as it should only accept old ttl signals on the 800 so I'm afraid that port 5 is your only option.

Damien

DolbySR · 21-07-2009, 3:33 PM

I use a SPATZ "Digiscaler" - on the manufacturer's website, there is only the new version of it without YPrPb Inputs but the rest is the same I think.

SPATZ DIGISCALE

I tried again on different resolutions, but BG800 cannot sync to it, only via my RGBHV to RGBS Converter box. Interesting: If I scale everything to VGA, there is no problem. SVGA neither. If I scale it to higher resolutions like XGA, SXGA... the blue raster starts to shrink on the left side and the top left corner of the red raster starts to go higher up...like on the pictures I attached on my first post in this thread.

Roland @ B4 · 22-07-2009, 8:01 AM

Quote:

Originally Posted by DolbySR

when I try to center the images on the tubes, green works great, red and bluw on the other hand are always at the end of setting range...not normal, eh?

1080p on an 800 is pretty hard going and the projector will not be able to reslove this. I would stick to 720p.

Part of your issue is a set up one.
Set your H V raster shift for R & B to their mid electric position.
Then use the brass trim pots on the Horizonatal and Vertical boards to get the rasters centred.
Make sure your R&B images are the same size too.
There are height adjusters on the Veretical board (white an blue pots next to the brass raster shifts and Width coils for the Er width.

That kick up at the start of the picture is not uncommon for the earlier projectors. You could try a mixture of H phase and Green H raster shift to see if it could be reduced

DolbySR · 22-07-2009, 8:57 AM

Quote:

Originally Posted by Roland @ B4

1080p on an 800 is pretty hard going and the projector will not be able to reslove this. I would stick to 720p.

Part of your issue is a set up one.
Set your H V raster shift for R & B to their mid electric position.
Then use the brass trim pots on the Horizonatal and Vertical boards to get the rasters centred.
Make sure your R&B images are the same size too.
There are height adjusters on the Veretical board (white an blue pots next to the brass raster shifts and Width coils for the Er width.

That kick up at the start of the picture is not uncommon for the earlier projectors. You could try a mixture of H phase and Green H raster shift to see if it could be reduced

Thanks for your reply.

Yeah, 1080p is quite hard, I know ^^ but since even the only swiss HD station broadcasts in 720p I will stick to that.

About this kick up...why does this happen at all? I noticed yesterday that on top of the picture, it is pulled to the left...don't know how to describe. It's like on those old tv sets when signal is poor, the top region of the picture is pulled to one side.

BTW, is it possible to feed Input 5 with RGBHV where H/V has simply been inverted? It will be a 5V signal...will it be accepted?

GrahamHodgson · 12-08-2009, 3:15 PM

looking at the images and from what you write I would say that you are using too much adjustment as a rule try to stick between 15 and 85% for best results. Only use fine convergence and not coarse (sorry cant remember if you have both on that modle) as they act against each other. If you have horizontal linearity then too much of this will cause the same effect try to keep between 30 and 70% for this. The left corner is always the worst because of the fly back pulse after you have done your centre line convergence try starting from that corner 1st and working around keeping to the above rules, it might help.