CurtPalme.com Home Theater Forum

[gjaky]

I have an interesting problem with my 6PG xtra.
With a full white picture the middle line on the red tube is darker than the others and it is seemed to be independent from input source. You can say the red tube is burnt, but there is absolute no visual wear on red tube, and here is an other thing: the same line on the blue tube is lighter at the middle than the others (also no visual tube wear), nothing strange on green. Because of the behavior of the blue tube I don't think it is tube wear, but what?
I also have a 9PG xtra to swap boards, but there are 20km between them -not to mention that sometimes I noticed this issue on that too...

[draganm]

sounds like banding from too much point convergence.

[gjaky]

No point board in this set...

[CIR Engineering]

What source are you using?

I have seen this with a few sat boxes and also an improper Radiance configuration.

If it is the source, try another, if it is a Radiance do a factory reset (menu-0-9-9-9) and see if it goes away... Though I doubt you are using a Radiance on a 6PG

craigr

[Tom.W]

Kind of sounds like this from the Baco FAQ.

Quote:

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.

[kschmit2]

excessive keystone or linear balance can also cause this

Kai

[gjaky]

Thanks!
I'll check out!

(I'm using it directly from HTPC and do not have Radiance )

[jarseneau]

I think there's also a pin-balance to check.

[benny]

99.9% certainty it will be caused by excessive use of vertical linearity balance on the red and the blue. It is a common issue on PG's and usually stems from a poor physical alignment to the screen and/or incorrect centreing of the raster on the tube face.

The lighter line on the blue is caused by the top and bottom half being pulled apart, and conversely, the red is having its halves overlapped slightly at the midpoint.

Null out the values for both red and blue, then revisit the linearity controls for the green. There will be a bit of to-ing and fro-ing to get all 3 tubes behaving uniformly.

If you still can't get satisfactory results, recheck your physical alignment and raster alignment.

Cheers,

Russ