AVS Forum banner

Status
Not open for further replies.
1 - 20 of 20 Posts

·
Registered
Joined
·
18,501 Posts
Discussion Starter #1
This is a new one on me. I had a customer pick up an XG 110 from me today. It was here on consignment, and had 1680 hours on it. I put about 50 hours on it to ensure proper running. Very light green wear, all original NEC tubes.

\\

He used the Nokia test pattern from his laptop that I haven't used in the past, and ran various resolutions on the set. Something came up that I haven't seen before. In the focus test pattern, where there are concentric sqaures in the middle of the image and one in each corner, the vertical sides of each square looked reddish. It did it on all resolutions and all refresh rates.


We didn't see it on the LCD monitor on his laptop, and all other test patterns and video image/desktop patterns looked just fine, as did icons and anything else we displayed.


I'm posting more for curiosity's sake rather than a cure. Is this normal when using the Nokia test pattern, unique to NEC's, or is there some tiny fault in this set that isn't seen other than on this test pattern?


Thanks!
 

·
Registered
Joined
·
299 Posts
Curt, I use this all the time on my XTRA and have not noticed that. It could possibly be caused by the VGA output on the laptop.
 

·
Registered
Joined
·
12,571 Posts
I just checked on my monitor and it didn't have the problem. I will check later on my laptop hooked into the pj to see if it exhibits itself there. Kal and Ray are probably correct.


Ericglo
 

·
Premium Member
Joined
·
2,101 Posts
I have used both nokia versions on very regular occasion (daily sometimes!)


never noticed that on any pj.



could a high screen gain cause this?
 

·
Registered
Joined
·
18,501 Posts
Discussion Starter #6
It's not the screen, I'm guessing the source. The customer knows about this thread and hopefully will post the outcome.


Thanks!
 

·
Registered
Joined
·
6,141 Posts
That artifact is not visible on my computer. And this monitor is about as good as they get!


(21" Sun Microsystems premium model, intended for CGI authoring. Made by Sony.)


CJ
 

·
Registered
Joined
·
1,425 Posts
Not ever seeing that pattern before I can only guess that the area of interest is made up of thin vertical lines, close together? If so it could take high video bandwidth to reproduce. If the three video outputs don't have the same response strange things like descibed can happen.
 

·
Registered
Joined
·
10 Posts
I just hooked the video output of my laptop up to a scope, here are the results:


The first image below shows the red output when displaying alternating white/black vertical lines one pixel wide. The second image shows the same except the lines are two pixels wide. Resolution was 1400x1050 @ 60Hz, out of a Mobility Radeon 9700, with a 75ohm termination resistor on the scope.


The high and low pulse widths seem very similar, so I don't think the problem is with the computer. My best guess is that the red amplifier has a longer fall time than rise time for some reason, causing the average video level to be too high. This doesn't cause any noticeable problems for normal video, though.


I'll try to get a picture of the problem soon. You can find the test app I used by googling "nokia monitor test"



David

 

·
Registered
Joined
·
1,425 Posts
Nice pictures. It will take the best of the projectors to properly display the one on one off pattern. Video BW > 100MHz.
 

·
Registered
Joined
·
10 Posts
I finally got the PJ setup properly today, and I took a picture of the problem.


The attatched pic was taken at 1280x720 @ 72Hz. The problem is not due to misconvergence or aliasing with the camera's CCD. Bandwitdh on the XG110 is 120MHz, so that's not the problem.


On other resolutions, like 1400x1050, the problem shows up on all colors.


Nothing really to worry about, but interesting.
 

·
Registered
Joined
·
6,141 Posts
I've seen enough variances in video card performance to easily account for that.


If you have access to a really excellent CRT monitor like a 21" professional Sony, you will be

able to use it to determine just how clean the video card's output is.


I found that my ATI Radeon 9600 Pro has a very clean output, while an NVidia FX5200 has a sloppy output in direct comparison, with shadowing, ringing, and even a bit of chroma delay evident in its output. It was bad enough that it made text hard to read at high resolutions.


CJ
 

·
Registered
Joined
·
10 Posts
I just tried it on a Dell P1110, a rebadged Sony 21" monitor. The problem still occurs, but this time it's too dark on the vertical lines, instead of too light. Based on this and the scope screenshots above, it must be the monitor/projector. I can't see how the card could output a signal that would be light on one device and dark on another.
 

·
Registered
Joined
·
10 Posts
That seems logical, but I don't know of any way that a bad signal would appear light on one device and dark on another.


I have to conclude that either both the PJ and the monitor have a problem, or there's somthing I'm missing here.
 

·
Registered
Joined
·
515 Posts
Is it safe to assume that convergence with the internal test patterns are spot on, but convergence with nokia is off?


I ask because I converged my XG spot on with the internal test patterns, but the nokia pattern being 1px and finer, were slightly off. So I had to fine tune again.

Ok so maybe they aren't spot on with the internal patterns, but the lines were so thick I couldnt tell.
 

·
Registered
Joined
·
10 Posts
Convergence was done with Nokia patterns, and is as good as I can get it. This isn't realated to convergence, as the same increased brightness shows up when the camera is out of focus, averaging the brightness out, and with only the red tube on.
 

·
Registered
Joined
·
6,123 Posts
Reduce the contrast and see if it effects it.


Chip
 

·
Registered
Joined
·
1,425 Posts
Silly question maybe, but are the R, G, and B coax cables between the video card and projector the same type of coax and the same length? Are the BNC connectors hooked to the wire good? Not like mine where I have to twist the red just so to get the picture right?
 

·
Registered
Joined
·
6,141 Posts
Is the focus as good on red as it is on green or blue?


Accept that the test patterns don't have the anomalies in them that you're seeing. The anomalies are therefore coming from any part downstream, be it the video card, the cables, or even the input circuitry on the PJ.


CJ
 
1 - 20 of 20 Posts
Status
Not open for further replies.
Top