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Barco 1209s sudden chromatic aberration.

 
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SPL800




Joined: 10 Nov 2009
Posts: 164
Location: Israel


PostLink    Posted: Tue Feb 18, 2020 8:12 am    Post subject: Barco 1209s sudden chromatic aberration. Reply with quote


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After watching a movie for about two hours, all sorts of color distortions began to appear in different parts of the picture. Mostly in face scene. and mostly on White bright areas.
i would say there is a problem with the brightness level that is very high. and causing this chromatic aberration

Right now I see a situation where I lower the brightness and contrast to zero and still the image is very bright.
black level still remains on the picture but it looks like very high gain of colors is reaching the tube.
you can see in the pictures marked in black the chromatic aberration mostly on faces scene.
G2 adjustment is ok
17.5v is also ok



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Last edited by SPL800 on Tue Feb 18, 2020 2:15 pm; edited 1 time in total
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kal
Forum Administrator



Joined: 06 Mar 2006
Posts: 17850
Location: Ottawa, Canada

TV/Projector: JVC DLA-NZ7


PostLink    Posted: Tue Feb 18, 2020 1:37 pm    Post subject: Reply with quote

What projector?

Kal

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My basement/HT/bar/brewery build 2.0
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SPL800




Joined: 10 Nov 2009
Posts: 164
Location: Israel


PostLink    Posted: Tue Feb 18, 2020 2:16 pm    Post subject: . Reply with quote

kal wrote:
What projector?

Kal


Opss my bad its barco 1209s
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garyfritz




Joined: 08 Apr 2006
Posts: 12024
Location: Fort Collins, CO


PostLink    Posted: Tue Feb 18, 2020 3:06 pm    Post subject: Reply with quote

[pedant]
Being picky, that's not chromatic aberration. Chromatic aberration is the result of lenses bending different colors (wavelengths) differently. It's a fixed property of the lens, so there's no way it could suddenly show up. What you're seeing is something in the video circuitry.
[/pedant]
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SPL800




Joined: 10 Nov 2009
Posts: 164
Location: Israel


PostLink    Posted: Tue Feb 18, 2020 7:13 pm    Post subject: Reply with quote

garyfritz wrote:
[pedant]
Being picky, that's not chromatic aberration. Chromatic aberration is the result of lenses bending different colors (wavelengths) differently. It's a fixed property of the lens, so there's no way it could suddenly show up. What you're seeing is something in the video circuitry.
[/pedant]

So you would recommend to try to replace the RGB board?
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garyfritz




Joined: 08 Apr 2006
Posts: 12024
Location: Fort Collins, CO


PostLink    Posted: Tue Feb 18, 2020 8:00 pm    Post subject: Reply with quote

I don't know. You need somebody who knows that projector -- I don't. I was just clarifying the use of the term "chromatic aberration."
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kal
Forum Administrator



Joined: 06 Mar 2006
Posts: 17850
Location: Ottawa, Canada

TV/Projector: JVC DLA-NZ7


PostLink    Posted: Tue Feb 18, 2020 9:28 pm    Post subject: Reply with quote

Does it happen on all 3 colours or only one? It's hard to tell from the pics. Throw up some test patterns and see. If only one could be something about one of the neckboards that is causing issues at 100% contrast (or close to 100%) with it clipping/oversaturing and not lowering the signal after.

Then I'd try swapping boards in the video chain.

Kal

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SPL800




Joined: 10 Nov 2009
Posts: 164
Location: Israel


PostLink    Posted: Tue Feb 18, 2020 9:49 pm    Post subject: It’s the RGB video board Reply with quote

I replaced the last RGB board that I have from curt (bought 2 in the past lucky me) and problem solved.

Can there be any good reason for replacing 2 board within one week?
Can anyone find what can cause this board to fail so easily?
on the RGB board i disconnected another small board that was attached to it what is this board?



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Hulio




Joined: 15 Apr 2006
Posts: 469
Location: Belgium


PostLink    Posted: Thu Feb 20, 2020 3:01 pm    Post subject: Reply with quote

That is R762745 quad decoder+comb filter, part of Barco's proprietary line multiplier/scaler (LiDo, LiMo, LiMo Pro) in later projectors.
Normally, it is not needed for HD signals, only composite video. So could be the reason of your problems, as the comb filter contains the luminance (your high contrast level problem) and chrominance (your colour shift problem) filters.
Probably failing electrolytic capacitors on it, not 105C degree rated.
On the replacement RGB switcher, is also this board mounted ? Remove it from the old board, and see if you still get the earlier problems after 2 hours video watching.
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