Film-Tech Forum ARCHIVE: Christie CP2220 red/green blemishes

This is topic Christie CP2220 red/green blemishes in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Christian Hove (Member # 6743) on 10-31-2016, 07:46 AM:

One one of our CP2220s we are experiencing static red/green colored blemishes near the center of the image.
The blemishes are pink on white test pattern and green on black image.

Changing the lamp does not solve the problem.

White test pattern:

Black:

Anyone got a clue what is going on?
I've made the original pictures avaliable here:
https://www.dropbox.com/sh/uswksfsosacdnr9/AADiqU9B7NPhYZ998usCR_uha?dl=0

In the shared dropbox folder, there is also a video recorded during lamp alignment - The video shows that the shape and intensity of the blemished changes with the lamp position in the mirror.

Thanks,
Christian

Posted by Steve Guttag (Member # 268) on 10-31-2016, 10:12 AM:

Generally, when you have colored blemishes, that indicates an obstruction on one or more of the colors. When you put up just green do you find that blemishes are where the magenta ones were but now they appear "black?" That would indicate that those parts of the green imager are being obstructed (dirt).

Posted by Carsten Kurz (Member # 5396) on 10-31-2016, 02:59 PM:

I'd say, call a tech in for cleaning.

- Carsten

Posted by Marco Giustini (Member # 4544) on 10-31-2016, 03:41 PM:

Are there techs (besides Mark) who can clean the engine one site?

Posted by Steve Guttag (Member # 268) on 10-31-2016, 04:52 PM:

I think it depends on the projector as to what one can do, on site. NEC is the most open and affords one the best chance at cleaning (then again, it s more likely to get dirty too).

Posted by Christian Hove (Member # 6743) on 11-01-2016, 06:53 AM:

Thank you all for your replies.

Yes Steve, with green test image, the blemishes turn black:

Posted by Steve Guttag (Member # 268) on 11-01-2016, 05:16 PM:

Well there you have it...you have dust/dirt on your green imager...that is what needs to be cleaned/blown out.

-Steve

Posted by Rex Oliver (Member # 7593) on 11-02-2016, 01:40 AM:

Looking at these problems--so reminds me of doing color purity adjustments on old RCA color TV's!

Posted by Christian Hove (Member # 6743) on 12-13-2016, 08:39 AM:

Just an update:
The blemishes has disappeared by themselves without any cleaning - I am happy but somewhat mystified...

Posted by Dave Macaulay (Member # 813) on 12-13-2016, 09:06 AM:

The light engine has air blown across the DMDs by the "LAD Fan" (Laminar Air Devices?) which should keep dust from sticking on the DMD and prism faces.
I would want to open the top and check there's no water ingress or coolant leaks.

Posted by Steve Guttag (Member # 268) on 12-13-2016, 09:33 AM:

I'm with Dave on this one.

Posted by Mark Gulbrandsen (Member # 72) on 12-14-2016, 10:15 AM:

I'm not a real fan of the laminar air flow system in those to be honest. The filters in the projector are not capable of keeping out moisture or popcorn oil.

Mark

Posted by Marco Giustini (Member # 4544) on 12-14-2016, 03:32 PM:

neither am I. Some minute dust will eventually build up, killing contrast. Unless there is a way to clean that path I rather have a sealed engine.

If your engine requires cleaning, I am told BTW that Christie in some countries are not honouring the warranty for projectors which are NOT operated in filtered-air environments - can anybody confirm?

Posted by Mark Gulbrandsen (Member # 72) on 12-14-2016, 08:07 PM:

Yes, exactly! I can see it might help cool the face of the DMD if you are running large lamps, other than that it's a marketing gimmick. Not sure about booths having to have filtered air. Most do, but only to a minor extent. Filtering air really well in a giant space is very costly.

Mark

Posted by Marco Giustini (Member # 4544) on 12-15-2016, 12:41 AM:

Christie clearly claimed that the LAD is not for cooling the chips, only for keeping them clean.

Posted by Carsten Kurz (Member # 5396) on 12-15-2016, 06:16 AM:

The idea itself is not so bad, as long as you don't have greasy air. It won't keep as clean as it would be after a real cleaning, but it helps to avoid dust buildup over a longer time. If you have greasy air, it's worse. The Sony 51x use the same approach, but they really should have designed better filters for these entries.
It seems Sony designed these to be used within the rooms these projector were actually built in...

- Carsten

Posted by Marco Giustini (Member # 4544) on 12-15-2016, 09:15 AM:

Carsten

There is now a retrofit kit for the 51x series which basically brings R320's filters to the 51x series. It seems very interesting to me.

That said, I like the sealed engine but if that is not possible, then I like Sony's approach where you can clean everything in 45 minutes.

Posted by Sascha F. Roll (Member # 9043) on 12-15-2016, 09:28 AM:

Marco, it's not only very interesting but also VERY expensive (AFAIR 1500 € net) for what it is... Could not convince one customer so far.

Posted by Mark Gulbrandsen (Member # 72) on 12-15-2016, 07:10 PM:

quote: Carsten Kurz
The idea itself is not so bad, as long as you don't have greasy air.

And where in the world is the air not so nasty any more? Some of the places I service which supposedly have such clean air like Jackson, Hole, Wyoming and Ketchum, Idaho actually have the dirtiest air filters out of all the sites I go to. Even Mike Blakesley's theater which has coal trains running back and forth in front of it all day doesn't get as dirty.

Mark

Posted by Marco Giustini (Member # 4544) on 12-16-2016, 05:54 AM:

Based on my experience I feel that the best solution it's to exhaust the air in the room itself and install air conditioners - more than just one unit if course.
That way the air is being reused and dust never gets in. If you cannot afford a proper filtration, that IMHO is the best solution. Just make sure you have two independent AC units.

Posted by Steve Guttag (Member # 268) on 12-16-2016, 07:52 AM:

quote: Mark Gulbrandsen
And where in the world is the air not so nasty any more?

I've found it! We service a museum in Virginia that due to the artifacts, they have VERY clean air. In their 3D theatre, I pulled out filters with over 3000 hours on them since I was last there, they looked pretty much new. In fact, no dust anywhere in site in or on top of anything.

Clearly, not a commercial cinema!

Posted by Marco Giustini (Member # 4544) on 12-16-2016, 09:48 AM:

cool!

I am not an HVAC engineer but it shouldn't be a huge investment to install a fan that brings air in and put a pollen filter on its way. It was critical with 35mm, with Digital your projector will thank you in the long term.

Posted by Mark Gulbrandsen (Member # 72) on 12-16-2016, 02:31 PM:

Steve, I wish all theaters had air systems like that one! Filter companies wold go out of business... Processing/preservation labs almost always have well filtered air sources too...

Mark

Posted by George Germisashvili (Member # 6597) on 12-17-2016, 10:47 PM:

And what regarding the level of cooling liquid in tank of cp2220 ? Did you add cooling liquid anytime ?

Posted by Marco Giustini (Member # 4544) on 12-18-2016, 01:40 AM:

If needed, but there should be no need. If level is low you probably have a leak. After a few years a little top up is OK

Posted by Mark Gulbrandsen (Member # 72) on 01-27-2017, 12:52 PM:

That's not what they told us at training way back in 2005! They claimed that the LAD does help cool the DMD's a bit. And how could it not unless your booth air going in is really hot.

Mark