CurtPalme.com Home Theater Forum

[telecine]

I'm in the middle of setting up my Barco 808 with an HD Fury and Sky Hd Box (I'm in the UK). Up until now I've been watching upscaled satellite via a Lumagen Vision Pro at about 864p50, and the same with SD DVD's.

Using the component Y signal from the Sky box into the G input of port 3 for the time being (I have an HD Fury problem which won't give me anything above 576p, but that's another story in another thread). This at least gives me something to set up while I'm waiting for HDMI to DVI cables to sort out my other problem.

Anyway, the active picture area in 720p50 or 1080i50 is tiny with respect to the raster. ie. the front and back porch intervals are huge.

This has all been documented before, and the general concensus of opinion was to use a Scaler to sort out the timings.

This isn't an option in my case, and I'd like to max out the width in other ways.

When I was using the Lumagen, I simply opened out the raster until the active picture area was within a couple of mil. of the tube edge. I've been running that way for about 3 years now with no problems, and no shattered glass either!

Has anyone opened up the scans even further using "stock" 720p50 timings to almost fill the tube face?

I was never worried with upscaled 625/50 because the porches were reasonable. With 720p50 however, there's going to be quite a lot of overscan off the tube face. The tube will be well and truly cut off as previously during this period, but has anyone actually done this?

I'm inclined to think that as the beam current is very small, in fact cut off during re trace, that this will be okay.

What do you guys think?

All the best.

[Ile]

It's impossible to get good hd picture without raster overlapping tube face in Barco. These like big porches and this wont do any harm to projector, just keep active picture 2-7 mm inside tube edge. With 1080 raster need to overlap quite much, otherwise picture size would be like stamp in the middle of tube face. Ofcourse you can use few mm porches, but you get bad raster ringing to left edge of picture and that would burn to your tubes. Chance porches bigger until there is no ringing. Adjusting active picture to the right edge of the raster helps to get it working with as small porches as possible, that makes picture little sharper and stress less h-deflection board.

I tend to blank overlapping unused raster.

[telecine]

Hi,


That's pretty much what I thought. Unfortunately It's going to mean re aligning all of my previous memory blocks too, as I have run out of H width and will need therefore to turn up the master width on the SMPS to get 720p "right". Hopefully there will still be enough range on the remote to shrink everything else (ie 864p via the lumagen etc.) back down again!

Since I'm not using a scaler to adjust the front and back porch (I don't have an HD scaler), I guess there will be a bandwidth compromise, and as I am using the infamous 75Mhz RGB amps maybe I'm asking too much.

I keep meaning to do your ABL mod, but I'm not sure my eyes are still up to it! Everything was so much easier in the old days before surtace mount components!



Thanks for your reply!

[telecine]

Today I tried to increase the the width of the scans to fill the tube face, but unfortunately there comes a point where the line scan will intermittently try to collapse. I guess the power supply is just running out of steam.

Is there any way to get around this?

This is a real shame as it would seem at this point that it's impossible to fill the tube face at 50hz in HD without the use of a scaler to adjust the porch timings.

The best I can do at this point is get within about 15mm of the tube edge, which results in an on scree image that is nowhere near big enough for my current set up.

Any suggestions?

[Ile]

I haven't tested Sky Hd Box, but I remember that it have some problems with porches.
So probably it won't work pretty well without scaler.

[telecine]

Presumably when I get the HD Fury working properly, the analogue outputs from that won't differ timing wise to that from the component outputs on the Sky box? It would be nice if the porches were a little narrower to say the least! I guess that won't happen though as it's probably just an analogue representation of what's coming out of the HDMI port.

That being the case I guess I'm screwed without a scaler. Is everyone using a scaler to do this?

Regarding the "pulsing" of the width when getting to the upper limit. I imaging this is a protection circuit coming into operation?

Thanks for your help so far!