CurtPalme.com Home Theater Forum

[sdumas]

Hi Everyone,

I have a BG808 connected to a HTPC with a Radeon 4850 - DVI to 5BNC via an Extron switch.

I use Powerstrip and I can't get the settings right. The PJ works great at 720p, but I can't make it run "clear" at 1080i or p. I get wavy lines. When I start a video player like Total Media Theater, the whole image is zigzaging sideway making unpredictables waves.

I tried some of the custom settings for 1080i at 24hz - yikes was that flickering. I increase the frequency until about 70hz and it was still quite shaky. I could not go higher as the PJ starts to show darker colours and then suddenly I lose all display.

At 60hz it was kind of OK, but when I start the videoplayer, same thing, totally wavy. When the image is stable (a few seconds at a time) it is incredible, but I would love it to be stable all the time.

Does anyone have a complete Powerstrip timing for a Barco BG808? Of course preferably with a Radeon 4850, but I suspect that any other Radeon should be about the same.

Other issue - I get a very thin horizontal line in the middle of the screen in 720p. It appeared only recently I think with a recent release of CCC. It is very annoying and I don't know how to get rid of it. It is very small and is annoying in a bright background, almost like if the screen is split in two sections. This line only appears on the Barco - I have a regular monitor that I connect to it sometimes and the line is not on it.

Thanks for your help!

[Ile]

Have you set syncs polarity to negative from Powerstrip?

Does your player software have some own sync settings in menu?

Bright horizontal line is different problem.

From
http://www.curtpalme.com/forum/viewtopic.php?p=66485#66485

Q: I have an odd horizontal line visible at times, what is it?
A: At times you may see a horizontal line that fades in the middle of the picture but it quite visible at one end (often the right side), it will be most visible on bright scenes, all white fields or light blues. This is called the horizontal line of coincidence, to some extent it's natural on some models of projector but careful adjustment can remove or at least minimise it. Pause a scene where the line is plainly visible, note which side it shows the most, go to a genlocked pattern and adjust horizontal skew to lower the horizontal centre line on the opposite side to the worst one. Do this by only a small amount, say 4-5 clicks. Now adjust top and bottom keystone to correct the error the skew change introduced. Go back to the picture, is the line less? If it's worse you skewed the wrong way, if it's better carry on tweaking the skew and keystone to minimise or remove the line. You may end up with a horizontal skew error that's plainly visible on the test pattern, it should not be obvious on actual video. Excessive use of horizontal bow may also make the line worse, again it should be possible to reduce the effect by adjusting horizontal bow and correcting the resulting top / bottom bow errors. Removing the line completely may not be possible but you should be able to reduce it to an acceptable level. The line is caused by the projector set-up making several scan line converge as they cross the tube face, result: one large visible scan line.
If deflection coil angles are set wrong or the projector is not mounted flat it will not be possible to remove the line. To check deflection coil angles check the projector is flat with a spirit level, check the screen is flat with a spirit level, sent horizontal skew to 49, delete convergence settings for that block (see this answer). Go to convergence and exactly centre red and blue on green using only the middle zone (actually raster shift). Now check the green horizontal line is parallel with the ground and that both red and blue exactly match green. If anything is wrong you have deflection coil angle problems. Correcting this will require all blocks to be deleted and the projector set to mid point in the service menu. At this point also check raster widths at approximately the scan frequency you intend to use (do this on an internal test pattern), this may save you a lot of convergence problems, including instability.
If you bought your projector from us deflection coil angles are definitely right, we do all projectors on an engineers table. If you seem to have a problem make sure the projector is mounted level. If deflection coil angle was set for a ceiling install and the projector is floor mounted there will be some error, and vice versa.

[sdumas]

Yeap polarity has been set to negative sync.

It's the res I can't get right. It's either extremely flickering, or when the flickering is acceptable, the image will wave when the player is playing.

As for the line of coincidence, I'll read a little more about it. The thing that puzzle me, is that it did not use to be there. I had a Nvidia 8600 and it was fine, I upgraded to a Radeon 2000 and i thought it was fine at first and then during an upgrade of CCC, the line appeared. I switched to a Radeon 4850 and it is still there. I'll try to go back to an older version of CCC to see if CCC is the problem. If it is not, then I'll try the procedure aforementionned.

[tommo2]

Is the cable running to the projector excessively long? The higher the refresh rate and resolution, the more lossy the cables can become. It is interesting that at 24Hz you have a picture, but as you increase framerate, the picture degrades.

Try using a shorter cable to connect from the HTPC to the PJ temporarily. If this helps you need a cable driver or better quality cable, or both.

[sdumas]

I'll try that.

I currently have my PC about 25 feet away from the projector. I use a VGA to 5 BNC cable adapter and then use RG6 from there to the PJ. - The RG6 are about 35 feet long.

[tommo2]

Yeah, just connect the VGA-5 BNC adaptor cable into the projector. If the pic improves, then a cable driver is needed.

I had a problem with poor quality picture before, and it was the long cable that was at fault.

It was fine at low resolutions, but at higher resolutions it would look terrible, and sometimes the picture was scrolling intermittently, as if the sync signals were so low that the projector had trouble "locking on" to the signal.
I used a short component cable from my xbox360 into the projector and all was fine. This component cable came with the xbox so it was good quality. I tried using a short vga cable that only cost a couple of dollars from Hong Kong (ebay) and the picture was terrible. It just goes to show that quality cables are important, even on short runs, especially when using high resolution (and hence higher frequency) signals.

Check out the thread:

https://www.curtpalme.com/forum_archived/viewtopic.php@t=6198.html

I eventually got to the bottom of it myself, and posted the results for everyone's benefit.

[sdumas]

Ok - I spent the past couple of hours testing a bunch of things - here are the results:

1) I move the PC close to the PJ and connected directly to the projector. This enabled me to actually get to 1080p resolution. I could not do that before. By doing this I effectively "bypassed" an Extron Amplifier (PS2 DA2 Plus) that I had, in order to get a standard monitor displaying at the same time as my PJ. But... it did not fix the waving of the image. The amplifier was in fact not allowing me to get the higher resolutions. Removing it from the line is something I need do and has been done now.

2) Since I was able to reproduce the issue close to the PJ, I put my PC back where it was and I did NOT connect the Extron amplifier back. This time I was able to also get 1080p. Basically same quality I had when I was next to the PJ. So I would say that my cables are good.

3) I tried to get 1080i (not 1080p) to sync on the PJ with Powerstrip - what I got, kind of puzzled me. I got split screen on the PJ. Two halves (top and bottom) identical but only showing half the PC screen (only the top part, and repeated on the bottom of the PJ). Each time I tried 1080i with Interlace, I got one of two things: either the split screen or a large "half" of screen; meaning only top half of the Windows screen that would fill the PJ. When I try to resize, it does not show me more then that top half. 1920 x 540p gave me similar results.

4) Back to 1080p I tried to modify the resolution to get it stable somehow. I could not get something that would not flickers or waves.

5) last interesting test. I am using a very stable 720p environment. (1280x720 - 61 hz). I decided to increase the frequency in order to see what would happen. I started to get a wavy image when I got to 72 hz.

I am now starting to think that it may be a Horizontal or Vertical board in the PJ that would be "weak" or defective.

Any comments or ideas on this?

I'd like to find out the following:
a) why do I have those wavy/shaky images at higher res/frequency
b) what can be done to prevent it
c) why do I have two half screens when I use 1080i
d) could it be a bad board?

[tommo2]

see if you can use another source (eg xbox360, ps3, blu-ray player to feed the pj either 720p or 1080i or 1080p.
If the results are the same, then the pj is at fault, and curt will be the best to advise what boards to send in for test/repair.

Im sure someone else here will have a better idea as to what exactly may be wrong in the pj, if it is indeed at fault.