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TOPIC: White color in film is shaky on screen

White color in film is shaky on screen 06 Jan 2005 11:35 #22089

  • puzzlegut
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This is going to be hard to explain but here is a problem we are having with one of our projectors (I think it's a Simplex). For a few weeks, we have noticed that when the projector is first turned on in the day, the white colors in the film (like the title on the green background previews) will look like they are raising. Before, they would normally go away after 15 mins and it would be good for the rest of the night. However, now it seems like it takes at least 30 mins before it goes away and it even seems like it does it everytime the projector is started. Does anyone know how to solve this problem? Any help would be appreciated.
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Re: White color in film is shaky on screen 06 Jan 2005 15:40 #22090

  • outaframe
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Sounds like you are having a shutter problem... When "cold" there seems to be enough lash in the gearing or bearings to cause this, and when the projector warms up the parts expand and the problem goes away... The cure may be as simple as adjusting the shutter, or may involve some parts replacement... Be certain that the shutter bearings and gears are getting lubrication, and try the adjustment first... White lettering on a colored (or black) background is the ideal situation to test for this problem...
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Re: White color in film is shaky on screen 06 Jan 2005 15:43 #22091

  • rodeojack
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Initially, it sounds like shutter ghosting, which would be a simple timing issue that you could fix fairly quickly.

However, being that your shutter is gear-driven, there shouldn't be anything in the mechanics that could shift enough to cause (or eliminate) what you're seeing.

Now that the problem seems to stay, I'd check the timing. Also, since you didn't identify the model of projector, check to make sure that whatever locks your shutter to its drive shaft is screwed down securely. If the shutter is moving around on the shaft, the resultant timing errors could cause the bleeding you see to drift.

It's a place to start!


Jack

ps... Outaframe's idea could be possible too, but I'd think you'd need either serious wear, misalignment (in the gear lash) and/or a shutter that's shaved or adjusted very near the point where timing would be pretty critical. That would indiate other problems in your projector that might have been in the making for a while. While you're looking into it, make sure the machine is properly lubed. If what Outaframe suggests is true, you could have some heat buildup in there. To cause that kind of expansion, you might notice something binding up (more stuff to check up on).

With the machine off, check to see if you have much/any play in the shutter shaft. Without moving other gears in the projector, the shutter shouldn't be able to move much at all. Offhand, 1/4" or so would be about as much as I'd think you'd want to see in there, if that much. The comment regarding the shutter being locked down should be verified first, though.

[This message has been edited by rodeojack (edited January 06, 2005).]
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Re: White color in film is shaky on screen 06 Jan 2005 16:30 #22092

  • John Pytlak
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It sure sounds like travel ghost, where the shutter is not in proper sync with the film pulldown by the intermittent. Could be as simple as a loose coupling, that tightens/loosens as the projector runs, or some binding of the mechanism as it changes temperature. Again look for any "play" between the shutter and the gear train driving the intermittent, or any "tightness" in the mechanism as you turn it over by hand.

At best, it is as simple as tightening the shutter hub on its shaft. At worst, you may have some worn gears or bearings.

John P. Pytlak, Senior Technical Specialist
Customer Technical Services
Entertainment Imaging
Research Labs, Building 69, Room 7525A
Eastman Kodak Company
Rochester, NY 14650-1922
Telephone: +1 585-477-5325 Cell: +1 585-781-4036 Fax: +1 585-722-7243
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Website: http://www.kodak.com/go/motion
John P. Pytlak, Senior Technical Specialist
Customer Technical Services
Entertainment Imaging
Research Labs, Building 69, Room 7525A
Eastman Kodak Company
Rochester, NY 14650-1922
Telephone: +1 585-477-5325 Fax: +1 585-722-7243
E-Mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Website: http://www.kodak.com/go/motion
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Re: White color in film is shaky on screen 06 Jan 2005 23:59 #22093

  • 4thGen
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This same thing happened with my Century projector head a few years back. Turning the shutter adjustment knob on the front of the projector did not eliminate the ghosting. We ended up replacing the vertical shaft in the back of the projector head and this solved our problem.
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Re: White color in film is shaky on screen 09 Jan 2005 20:18 #22094

I have run into the same problem today while working on the Art house booth. The shutter was getting out of time enough that it would almost fix it by the time you reach the end of adjustment with the timing knob. I reset the knob to middle settng and retimed the shutter on the shaft. After about 30 minutes of play the shutter was working its way back out of time. I think it is a worn gear on the vertical shaft or loose coupling in the shaft I will dig into this at a later point and let you know.

Simplex PR1050 Projector by the way.


[This message has been edited by GTEntertainment (edited January 09, 2005).]

[This message has been edited by GTEntertainment (edited January 09, 2005).]
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