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Posted by Joe Morris (Member # 1553) on 03-05-2003, 04:20 PM:
I have a nice shadow at the bottom of my screen. I had to change the bulb out due to the bulb being bad. The screen was dark along the bottom before i changed the bulb, and it is still dark along the bottom. The shadow goes completely along the bottom of the screen and extends about 6-8 inches into my picture. any ideas?
Posted by Matthew Nock (Member # 1575) on 03-05-2003, 04:35 PM:
Have you adjusted the vertical alignment of the bulb since replacing it?
it sounds as tho this isnt the problem tho because the shadow is straight across the bottom.
Posted by Randy Stankey (Member # 64) on 03-05-2003, 04:54 PM:
Take the lens out or open the turret and project a white beam of light onto the screen. (Don't forget to start the projector motor, lest you burn the shutter!)
What you should see on the screen is sort of a "bullseye" or "starburst" pattern of light. It should be almost perfectly symmetrical and centered on the screen. If not, you'll have dark areas in your picture.
Have a knowledgeable person adjust the lamp alignment and beam spread/focus until it is centered. If these adjustments can't put the picture back in line then you have a problem that a technician needs to look at.
Put the lens back in and take out the aperture plate. Project a white beam on the screen again. You should see an even white "wash" all over the screen. In fact, because the plate's out, you will see light going all over the wall! If you don't see this picture you might have a problem with your lens or with the lens alignment. If you don't know how to align the lens, have your tech do it. A small turn of the screw can make a big mess if you don't know what you're doing.
Finally, put the plate back in. Project a white beam again. If your picture isn't a perfectly white rectangle of light, centered on the screen you have a plate alignment problem. It could also be a maladjustment of your turret. Either way, get your tech to come in and look at it. It's likely just a quick adjustment with a piece of test film and an Allen Wrench. Again, one false move on the tinkerer's part can mess things up royal!
Of course, all this assumes that the projector is clean and there's no junk built up in the gate or aperture plate but, since you're here on Film-Tech, we don't have to worry about that, do we? ![[Big Grin]](biggrin.gif)
Posted by Paul Mayer (Member # 355) on 03-05-2003, 04:58 PM:
You might want to check the height of the lamphouse in relation to the picture head. Also ensure that the douser or any fire or changeover shutters are fully retracted out of the optical path.
Posted by Jack Ondracek (Member # 1466) on 03-05-2003, 05:20 PM:
Definitely check your dowser.
Also, if you're running a Century, make sure the fire shutter is opening all the way. I've had them get sticky in the past & do what you're seeing.
Posted by Joe Morris (Member # 1553) on 03-05-2003, 05:30 PM:
I checked my douser, my shutter, my bulb, my lens, aperature, i've checked it all...and I got the shadow a little smaller by adjusting the spread of the bulb. BTW: I'm using a CFS SX-2000 console...big hunk a junk, and a monee projector identical to the Century JJ's i think...at least the parts are. but my shadow is still there...
Posted by Darryl Spicer (Member # 711) on 03-05-2003, 06:00 PM:
Have you ever had the reflector bowl replaced at anytime that you know of. I had this problem before and had to move the reflector bowl forward torwards the projector in order to get rid of the darkened area.
Posted by Daryl C. W. O'Shea (Member # 1303) on 03-05-2003, 07:56 PM:
Does the light fill the screen without the aperture in?
Does the light spill above the screen with the aperture in?
Is this black area a well defined block with a straight edge?
Posted by Kenneth Wuepper (Member # 1174) on 03-05-2003, 08:33 PM:
Joe,
I have a question for you. Did you try inverting the aperture plate?
It is sometimes possible to invert the plates in the Century type apertures and that can cause your problem if the plate is fitted to cut at the top.
Just a thought!
KEN
Posted by Daryl C. W. O'Shea (Member # 1303) on 03-05-2003, 08:36 PM:
I wondered about that too Ken, but he said he 'checked the aperture'. Not sure what he checked about it.
Anyway, I'll toss in what I was going to add before...
Has someone (accidentally) swapped aperture plates with another machine (not necessarily from the same screen). That, is if you have more than one projector or multiple screens.
Posted by Dave Macaulay (Member # 813) on 03-05-2003, 08:51 PM:
Is the fire shutter or changeover plate not opening far enough?
A straight line dark shadow along the screen bottom is not a lamphouse problem in my experience, lamphouse problems tend to be curved (like the reflector). Most likely an aperture or changeover, or the whole console has shifted.
Posted by Daryl C. W. O'Shea (Member # 1303) on 03-05-2003, 09:15 PM:
I don't know why I missed this before...
Does the problem only occur with a single lens / aspect ratio or does it happen with all of your lenses (flat and scope and others?)?
I agree with Dave that the problem is likely forward of the lamphouse, that's why I asked above if the black area was a straight line.
Posted by Joe Morris (Member # 1553) on 03-05-2003, 09:48 PM:
I have a Vertical lamphouse..i'm thinking that my mirror has been moved somehow...I will have to wait until I'm not showing a movie in there to check. I know it's not my aperature, it happens on both flat and scope prints, with or without the aperature. I haven't had the reflector dish replaced in 14 years...so it's not that. I will check my mirror and see what that does
Posted by Rick Long (Member # 213) on 03-05-2003, 11:18 PM:
Willing to bet that the centrifical-driven fire shutter isn't opening all the way. These things do slip over time. Check the manual for proper adjustment. Only requires a screw-driver.
Posted by Gerard S. Cohen (Member # 994) on 03-06-2003, 10:41 AM:
Rick (above) nailed a problem I had long ago when working replacement at a single-screen in NYC. Lord knows how long the problem existed, but I traced it to a hanging fire shutter, and I was not able to correct it at the time. I reported it to the night manager, who called the Union office, and two men came down and tried to adjust it. The chain owner was alerted. He was a notorius alcoholic, and came down roaring drunk, spouting obscenities and cursing me out. I was trying to run a perfect show, but he didn't appreciate my efforts.
I vowed never to work any of that man's theatres again, and never did.
Posted by Mark J. Marshall (Member # 1409) on 03-06-2003, 11:23 AM:
We have a changeover that doesn't open all the way sometimes. The result is a shadow on the bottom of the screen.
Posted by Joe Morris (Member # 1553) on 03-06-2003, 12:52 PM:
okay, it's the fire shutter, now how do i fix it on a Monee Universal MSP??
Posted by Daryl C. W. O'Shea (Member # 1303) on 03-06-2003, 06:22 PM:
My quick and dirty adjustment is an elastic band to hold it up. There is a way to adjust it though, but having never used a Monee I don't know. Usually it is as simple as turning a screw on the fire shutter unit. If you have a manual for it, it'll surely tell you how.
Otherwise, Rick will know how.
Posted by Randy Stankey (Member # 64) on 03-06-2003, 09:22 PM:
Do you NEED the fire shutter?
You have a console dowser on the lamphouse, no?
The projector has a changeover dowser, no?
The fire shutter is a vestigial part unless you run nitrate. or If you have a "hot" lamphouse and would like to use it to prevent the film from melting so badly that's another reason to keep it. You have a CFS, though. They're not known for their ability to burn film quickly. ![[Wink]](wink.gif)
If your booth isn't nitrate-safe you don't technically need it.
If you're trying to keep your projector in as close to original condition as possible you may want to leave it in. You could carefully remove it and just save all the parts.
Posted by Joe Morris (Member # 1553) on 03-08-2003, 12:04 AM:
thanks guys, I checked on one of my other projectors to see what i was missing. of course, on that particular projector...it was the fire shutter. so naturally checking the other 6 projectors, i figured out there's a stupid set screw that slipped down the vertical main drive shaft. thanks for all the help guys! ![[thumbsup]](graemlins/thumbsup.gif)
Posted by Steve Guttag (Member # 268) on 03-08-2003, 09:55 AM:
Randy,
Just because one doesn't NEED (as a matter of law) a fire shutter doesn't mean they are not a good idea. The concept is simple, if the projector is not running fast enough, the film is not exposed to the light/heat source. They are a good idea.
A machine that has a sloppy fire shutter often is sloppy though and through. Given a choice, I'll always take a machine with a fire shutter over one without.
Steve
Posted by Joe Morris (Member # 1553) on 03-08-2003, 04:09 PM:
Thanks steve.
This projector actually does run slower than the others...so it's probably a good idea that I put it back.....that and the owner might not be to happy with extra parts laying around...
Posted by System Notices (Member # 2357) on 04-06-2005, 03:40 PM:
It has been 759 days since the last post.
Posted by Dominic Espinosa (Member # 2122) on 04-06-2005, 03:40 PM:
What can be done however about a changeover douser on a Century that doesn't lift completely up and out of the way?
I've currently got this issue on one of my machines.
It's a Century SAW outfitted with a Kelmar electric changeover.
If I lift the douser by the pushrod or tie rod just slightly, not like the changeover is sticking, but just enough to take up the play in the linkage it clears up but because it's just a slight mechanical play it's not going to stay up.
The only thing I could think of is moving shortening the tie rod by about 1/32" or some small ammount and moving the douser up just slightly on it (the tie rod comes all the way down to the back of the douser as it is) but then that could possibly lead to light bleeding through into the gate before the douser is open.
Advice? Did I miss the obvious answer?
Posted by Louis Bornwasser (Member # 3063) on 04-06-2005, 06:16 PM:
If you inspect the bellcrank (the triangle that converts lateral motion to up/down motion), you might discover another hole that is a better match for the actuator wire. This will result in more travel which, with adjustment of the blade/actuator wire, will translate into proper operation.
The Kelmar changeovers have always worked well on the machines for which they were made. Occasionally a force-fit works less well.
Louis
Posted by Mark Gulbrandsen (Member # 72) on 04-06-2005, 08:22 PM:
Actually there have recently been some issues with certain runs of brand new out of the box Kelmar C/O's. If you get one that seems to have sticky armatures over in their travel it is because the two coils are not quite in line.... they are just a tad bit offset from each other because the mounting holes are not machined quite correct. If you encounter this problem take it apart and grind flats along both sides of both armatures. This will allow plenty of side clearance so there is no sticking of the armatures in the bore of the coils.
Mark
Posted by Dominic Espinosa (Member # 2122) on 04-07-2005, 02:20 PM:
I dont' think it's the coils for the fact that, when I pick up the douser by hand after it's opened all I'm taking up is a very small amount of play, the pushrod moves all the way back just fine.
I'll have to check the bellcrank, I was sure I moved it to the furthest hole. If I didn't then once again I ask the stupid question
Thanks guys.
Posted by Louis Bornwasser (Member # 3063) on 04-07-2005, 08:29 PM:
There are no stupid questions! Answers, maybe.....
Posted by Dominic Espinosa (Member # 2122) on 04-09-2005, 04:56 AM:
Well, in the end it turned out that this one WASN'T set to the last hole on the converter dealie. Trouble was, moving it there put the tie rod at such an angle that it would bind against the projector casing.
In the end I used my pliers and bent the end of it slightly, this allowed free movement through the projector, of course now the issue was that it still wasn't perfect, the douser would drag on the guides. So after a little fiddling I ended up shifting the rear end of the changeover slightly out of line and it did the trick.
Posted by Louis Bornwasser (Member # 3063) on 04-09-2005, 07:45 AM:
Sounds like you may have an earlier vintage douser blade where the connection point is rigidly attached. Newer ones swivel slightly which usually solves the interference between the casting and the rod. Another problem with the old setup was that the blade sometimes would bind in the channel.
Your "fix" sounds good to me. Louis
Posted by Dominic Espinosa (Member # 2122) on 04-09-2005, 01:13 PM:
I don't think I've ever seen any other type of douser in a Century.
Posted by Louis Bornwasser (Member # 3063) on 04-09-2005, 03:30 PM:
No, I am referring to the old vs. new style Kelmar/Century blade.