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Marquee 8500 LC Lens Removal

post #1 of 12
11/15/12 at 11:22am
Thread Starter 
Need to take off my CRT lenses to get a picture of the actual tubes underneath for a wear balancing project. Can someone tell me what the size of the three socket allen screws are?
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post #2 of 12
11/16/12 at 8:50am
Thread Starter 
Excuse me, I meant the ones referred to for tightening the lenses - shown here.

I may have accidentally tightened the lower right screw. What does it do and is this anything to worry about? The manual just lists it as factory/service use only.
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post #3 of 12
11/17/12 at 4:59pm
That is for Scheimphluge adjustment, It levels the lens to the screen and tube face to even out the focus on the left, right, top and bottom of the screen. They all are used together to get an even focus across the screen. How many turns did you move it? Do you notice any focus difference across the screen?

Athanasios
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post #4 of 12
11/21/12 at 6:10am
Thread Starter 
Just a few turns, probably not even a full one. I will not be at the apartment until after Thanksgiving so I have no way to test it now. Pretty sure the bottom and top went out of focus, the top right corner specifically. I had never adjusted these before since we do not have the proper tool for it. When trying to adjust it back with the regular lens adjustments, I knew something was wrong. Do you know what is the proper bit size for these screws?

By the way, another question:

When there are very bright white scenes, such as with a cloudy sky, the picture will get streaks or waves that flow top to bottom through the picture. The first thing to do is clearly to isolate the projector on a different power plug and see if this continues, but has anyone else seen this before?
Edited by UncleWill - 11/21/12 at 6:18am
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post #5 of 12
11/22/12 at 4:38pm
Sounds like banding. Can you post photos?
Also what's your video chain look like?
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post #6 of 12
11/22/12 at 5:26pm
Thread Starter 
Here is a very crude video chain poster made for some roommates. Pretty sure this is on all video signals.

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post #7 of 12
11/22/12 at 6:24pm
Those waves might be a too high G2 on some tubes. Or a bad cable in the chain somewhere causing a ground loop. Id say its more of a ground loop with everything you have connected.

Start with just one piece of gear in chain and then keep adding till you find the issue if in fact its not there all along with no Equipment connected.

Athanasios
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post #8 of 12
11/23/12 at 5:50am
Thread Starter 
Perhaps I should throw up some internal test patterns to test out the waves? I think there is a big blank white one in there. Is there a guide to help adjust the G2 for each tube? The only one I ever used was a guide for grayscale calibration that someone on here recommended. I do not remember the page except it was selling CRT projectors and looked very close to this:
http://hometheater1.com/

Also, any word on what size driver I need to adjust the Scheimphluge? Would like to take care of that red tube blur.
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post #9 of 12
11/23/12 at 12:15pm
http://www.etechvideo.com/techtip1.htm
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post #10 of 12
11/23/12 at 12:37pm
Quote:
Originally Posted by draganm 
a standard 5/16ths allen wrench will work but the short end of the wrench will just barely clear the lenses, kind of a pain to adjust. I welded up custom wrenches in the past using stainless steel tubing and I found that 8.5" is a good length. See if you can find a long screwdriver handle style hex wrench to buy, might be hard to find though in that length, go to large hardware store like Harbor Freight.
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post #11 of 12
11/23/12 at 12:40pm
I went to Ace and got some long "T" handled ones, I also have the one Dragan is referring to in his quote. If you have no luck locating one I have one I can send you.
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post #12 of 12
1/11/13 at 9:42am
Thread Starter 
What are the default RGB focus settings in the service menu? Just got back into town and realized my reds were unfocused. The center is okay but the sides are out, particularly the bottom left hand corner. Yes, I've already tried the main focus adjusts.
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