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cliffbernard
Joined: 07 May 2007
Posts: 6
Location: Sydney
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| Posted: Mon Nov 05, 2007 9:50 am Post subject: yellow patches on all white screen |
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Hi all,
I'm not exactly a newbie. In fact, thought I knew a bit until I started browzing these forums. Now what I don't know could fill Nevada. So forgive me if this is too simple a question. I've got a Sony 1292, and recently had three factory new tubes installed--old stock from an HT buiness that went belly up. The tubes are fine, but on an all white screen, patches of the screen show as a dirty yellow rather than white. The tubes now have 700 hours on them and the problem is no better and no worse. If you project each tube individually, the color looks even, but put them together to make white, and parts of it look like snow where the huskies go. Any ideas?
Cliff
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dochlywd
Joined: 25 Apr 2006
Posts: 346
Location: Saint Louis, Missouri
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| Posted: Mon Nov 05, 2007 12:07 pm Post subject: |
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Other than wear on the tubes, I'm not really sure. You should contact Graham Johnson. He is considered the 1292 expert on all the forums. Oh, and the best thing................
HE'S AN AUSSIE MATE!!!!!!!!!!!!!!!!
Here's his contact info:
grahamrjohnson@yahoo.com
He should be able to help.
Doc
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Stonefool
Joined: 24 Dec 2006
Posts: 253
Location: Sweden
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| Posted: Mon Nov 05, 2007 12:09 pm Post subject: |
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Have you looked at the tubes without the lenses, while the pj is on? (I think this is the easiest way to see if the phosphor actually is 100% ok.)
_________________
Trying to get everything to work.
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garyfritz
Joined: 08 Apr 2006
Posts: 12088
Location: Fort Collins, CO
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| Posted: Mon Nov 05, 2007 1:10 pm Post subject: |
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Yellow = red + green. That suggests the blue is weak in the yellow areas. Are you sure of the condition of the blue tube?
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Elaine Benes
Joined: 25 Apr 2006
Posts: 1416
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| Posted: Mon Nov 05, 2007 1:30 pm Post subject: |
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Does the 1292 have zone contrast modulation for each color to achieve proper color at edge blends ? If so, did you zero out all zone contrast modulation settings for all colors ? If you didn't, that is likely your issue, and its the blue that is adjusted in a non-linear manner...
that's my guess anyway...
If you don't have zone contrast modulation, then I'd bet you have bad phosphor in your blue tube(which is why the splotches are yellow...of course).
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audimushroom
Joined: 25 Jun 2007
Posts: 44
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| Posted: Mon Nov 05, 2007 1:32 pm Post subject: Re: yellow patches on all white screen |
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Hello there
The 1292 has LC coupling and also has Glycol in front of each tube, its possible that you have fungus in the glycol and that would explain the random patches, when the tubes were installed was the glycol flushed and replaced with fresh?
Its amazing how cloudy that stuff goes over time, I woul expect it get worse though over time.
| cliffbernard wrote: | Hi all,
I'm not exactly a newbie. In fact, thought I knew a bit until I started browzing these forums. Now what I don't know could fill Nevada. So forgive me if this is too simple a question. I've got a Sony 1292, and recently had three factory new tubes installed--old stock from an HT buiness that went belly up. The tubes are fine, but on an all white screen, patches of the screen show as a dirty yellow rather than white. The tubes now have 700 hours on them and the problem is no better and no worse. If you project each tube individually, the color looks even, but put them together to make white, and parts of it look like snow where the huskies go. Any ideas?
Cliff |
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Curt Palme
CRT Tech
Joined: 08 Mar 2006
Posts: 24396
Location: Langley, BC
TV/Projector: All of them!
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| Posted: Mon Nov 05, 2007 1:58 pm Post subject: |
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With NECs I've found that you can minimize/get rid of the yellow patches by playing with the focusing zones. There's less blue light output in the yellow patches so while it could be text wear that you can't see even with the lenses off, I'll bet the focus adjustments will do it.
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
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| Posted: Tue Nov 06, 2007 2:28 am Post subject: |
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That's one reason why blue tubes are generally slightly defocused a bit as setup from the factory. I'll wager that the yellowish areas are
places where the blue tube is better focused then either red or green.
As a matter of fact, I look for that EXACT effect when fine-tuning the focus on my Marquee 9501LC. I do the final focusing of the blue
tube on a white screen. I try to make the screen uniformly yellow and then I drop the drive of red and green or boost it on blue to
get the white balance back to where it should be according to my colorimeter.
CJ
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cliffbernard
Joined: 07 May 2007
Posts: 6
Location: Sydney
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| Posted: Wed Nov 07, 2007 4:49 am Post subject: |
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| Stonefool wrote: | | Have you looked at the tubes without the lenses, while the pj is on? (I think this is the easiest way to see if the phosphor actually is 100% ok.) |
Thanks--yes, I have looked. I took the tubes out of their original boxes when they wre delivered. They were clearly brand new, and after 700 hours, theyre still pristine.
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cliffbernard
Joined: 07 May 2007
Posts: 6
Location: Sydney
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| Posted: Wed Nov 07, 2007 4:51 am Post subject: |
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| Curt Palme wrote: | | With NECs I've found that you can minimize/get rid of the yellow patches by playing with the focusing zones. There's less blue light output in the yellow patches so while it could be text wear that you can't see even with the lenses off, I'll bet the focus adjustments will do it. |
Thanks. Will consult the manual and try it. I'll let you know.
Cliff
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cliffbernard
Joined: 07 May 2007
Posts: 6
Location: Sydney
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| Posted: Wed Nov 07, 2007 4:53 am Post subject: |
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| Nashou66 wrote: | Off topic question. the new tube you got , did they have all the magnetics on them or did you swap thyem from your old tubes?
Athanasios |
Tubes were bare. I used the existing yokes. Culd there be something electronic causing the blue values to vary across the raster surface?
Cliff
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cliffbernard
Joined: 07 May 2007
Posts: 6
Location: Sydney
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| Posted: Wed Nov 07, 2007 4:56 am Post subject: |
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| cmjohnson wrote: | That's one reason why blue tubes are generally slightly defocused a bit as setup from the factory. I'll wager that the yellowish areas are
places where the blue tube is better focused then either red or green.
As a matter of fact, I look for that EXACT effect when fine-tuning the focus on my Marquee 9501LC. I do the final focusing of the blue
tube on a white screen. I try to make the screen uniformly yellow and then I drop the drive of red and green or boost it on blue to
get the white balance back to where it should be according to my colorimeter.
CJ |
Hey, thanks for the adivce. You're the second to suggest blue focus, and it looks like that might be the cuplrit. The tubes are pristine. I preume you mean EM focus? I've never fiddled with this, so is it possible to focuse separate areas of the screen?
Cliff
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cmjohnson
Joined: 03 Apr 2006
Posts: 5180
Location: Buried under G90s
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| Posted: Wed Nov 07, 2007 9:12 pm Post subject: |
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Not having played with a 1292, I'm not 100 percent sure if you have multi-zone EM focus or not. If you do, you can make some
adjustments in various zones to see if you can iron out the problem.
On a Marquee, you'd have nine focus zones plus the contrast modulation function to play with as well, which would allow you to
achieve a very even image all across. Or severely screw it up. 
You could either adjust for even yellow and then boost the blue drive a bit, or defocus a bit for even white instead. Being the
super-retentive type, I'll adjust for tighest possible focus and then adjust drive to balance out the colors.
CJ
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Chuchuf
Joined: 11 Mar 2006
Posts: 548
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| Posted: Thu Nov 08, 2007 2:26 pm Post subject: |
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| cmjohnson wrote: | That's one reason why blue tubes are generally slightly defocused a bit as setup from the factory. I'll wager that the yellowish areas are
places where the blue tube is better focused then either red or green.
CJ |
Uneven focus in the blue will cause areas of the screen to be yellowish. So your goal in setting up the B Focus should be to initially get the best even focus you can across the entire screen. Then defocus from the center position (which should evenly defocus the entire screen) as needed to correct the top end and grey scale.
The reason for defocusing B is to give you a flatter more even grey scale.
Terry
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