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Author Topic: Xenon Amperage???
Matt Close
Expert Film Handler

Posts: 226
From: Hervey Bay, QLD, Australia
Registered: Sep 2001


 - posted 05-17-2002 01:39 AM      Profile for Matt Close   Author's Homepage   Email Matt Close   Send New Private Message       Edit/Delete Post 
I have a CFS 2500W console (the one with the vertical lamp) ... and it is just never bright enough in my oppinion, and I get light flicker on the screen that comes and goes. The lamp is only 2 weeks old. What amperage should a 2500W xenon be run at? It currently sits on 24V , 72A ..... That's a little low aint it?

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Dick Vaughan
Phenomenal Film Handler

Posts: 1032
From: Bradford, West Yorkshire, UK
Registered: Jul 2000


 - posted 05-17-2002 06:23 AM      Profile for Dick Vaughan   Author's Homepage   Email Dick Vaughan   Send New Private Message       Edit/Delete Post 
2.5kW lamps should run around the 28V 90 Amp region .#
Most (all ) lamps should come with a data sheet in the box giving operating ranges.


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John Anastasio
Master Film Handler

Posts: 325
From: Trenton, NJ, USA
Registered: Sep 2000


 - posted 05-17-2002 07:10 AM      Profile for John Anastasio   Author's Homepage   Email John Anastasio   Send New Private Message       Edit/Delete Post 
It sure sounds like a power supply problem, but if that's been checked and it's okay, make sure that the lamp connections are tight. A high resistance there will also cause low current and a flicker. It'll also burn the heck out of the contacts. But you know that...so I'm putting my money on a power supply problem, like a bad diode. Does it do the same thing with another lamp?

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Pat Moore
Master Film Handler

Posts: 363

Registered: Mar 2000


 - posted 05-17-2002 09:21 AM      Profile for Pat Moore   Email Pat Moore   Send New Private Message       Edit/Delete Post 
Matt;

One man's opinion, but vertical consoles have almost always had an arc waver problem. You guys know we bought ORC a few years ago but could never make the problem go away satisfactorily in the Optimax. I think it's a combination of optical design amplifying the movement of the arc, and it really shows badly on the edges of the light field on screen.

Don't confuse arc waver with vibration problems that also seem to plague some of these consoles. The outer edge of that reflector, if unsupported, will "shiver" (for lack of a better term) and you'll see that on screen as well. The vibration will tend to be higher frequency and very rhythmic, while the arc waver is slower and more random.

That lamp should be running a little "hotter" and that 90A figure might be about right. That would probably allow you to defocus the lamp while maintaining good light levels on screen, and that might take some of that visible arc waver outside the aperture edge and off the screen.

Pat

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000


 - posted 05-17-2002 09:36 AM      Profile for John Pytlak   Author's Homepage   Email John Pytlak   Send New Private Message       Edit/Delete Post 
Pat Moore said: "One man's opinion, but vertical consoles have almost always had an arc waver problem. You guys know we bought ORC a few years ago but could never make the problem go away satisfactorily in the Optimax."

I'll second that. One of our Kodak screening rooms is equipped with the vertical lamp ORC Optimax consoles. What I would call "candlelight flicker" has always been an issue with them. We tried various lamps, and settled on Osram as being the best in that console, but the flicker never really went away. Also not the most efficient design for light output. But the 45-degree dichroic "heat mirror" that reflects the visible light and passes the infrared to an efficient heat sink, is very effective in reducing heat on the film.

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

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Randy Stankey
Film God

Posts: 6419
From: Erie, Pennsylvania
Registered: Jun 99


 - posted 05-17-2002 09:54 AM      Profile for Randy Stankey   Email Randy Stankey   Send New Private Message       Edit/Delete Post 
Your lamp is burning at 1728 amps. I would say that you shouldn't burn it at less than 2000.

In my old job, we used to burn them at 2200, more or less. Almost all of our consoles liked to run at about 28V and 80A. (2240 watts, to be exact.)

If you have power problems, you need to get down and check the taps and all the other connections in the projector right away. I've seen it many times. A person decides to change the tap settings and doesn't get the wires tightened properly. The loose connections overheat and burn the wires and the terminals.

I had a projector that actually did a "slow burn" because of this. The whole inside of the power supply was charred. The boost caps overheated and blew their guts all over the inside of the machine. I had to practically gut the whole power supply and rewire it. I had to replace a terminal block because it was so badly charred. I kept a couple of these in the trunk of the car just for the purpose... So you know this isn't an uncommon occurrence with these machines. (Especially if you have somebody who likes to tinker working in your booth.)

Right away... Go take the covers off the machine and get down on your hands and knees with a flashlight. (Wait till the projector isn't running. ) Start at the contactor and follow every wire along its path and check all the connections. Make sure they are tight enough that they don't move when you jiggle the wires.

There are six wires on the contactor. Check them to be sure. Follow the yellow wires from the contactor to the taps. (terminal blocks)
Make sure the ends of those wires are inserted into the terminals the right way and they are tight. (Don't move when you wiggle them.)
Check the black jumper wire. (The thing that looks like a giant letter "E".)
Check the wires that go from the terminals to the transformer windings.
Check the wires that come off the transformer and connect to the "tails" of the diodes".
Check where the diodes connect to the heat sink. (Did you use head sink compound?) (Test the diodes and replace any that are going out of spec.)
Check the heavy cables that come off the heat sink and go to the bulb.
Check the connections to the base of the bulb and to the "return" line from the bulb.
Check the bulb itself... Are the Allen screws that hold it in tight? Is the positive lead tight?

Literally, follow every wire that carries power to the bulb and check every connection. Look for charred ends of the wires and connections that are darkened.

I have seen at least a dozen CFS consoles where some form of this problem has occurred. It's not always the fault of a person. It's just the way these consoles were put together. The heat makes them expand and contract. Over time the connections all get loose from all those expansion/contraction cycles. You should go through these consoles like I just told you and check the connections every time you change a bulb.

Once you learn where to look it'll take you less than a minute to do this job. This it time well spent in order to prevent a disaster.

It took me a whole day to repair that burned-out console. I was so pissed off I could hardly speak. I just coudn't believe that those people were stupid enough to stand there and let the thing do that. They even told me that they noticed a "funny smell" every time they walked by that projector and the STILL didn't do anything. So, I asked them if they had any more "funny smells" and they told me that they did. I found two more consoles that were on their way to oblivion.

Let me tell you, I was spitting blood by the time I left that place!


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Rick Long Jr
Expert Film Handler

Posts: 211
From: Toronto, Canada
Registered: Jul 2000


 - posted 05-17-2002 10:27 PM      Profile for Rick Long Jr   Email Rick Long Jr   Send New Private Message       Edit/Delete Post 
Yup, every day, this job just keeps getting better and better.

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Matt Close
Expert Film Handler

Posts: 226
From: Hervey Bay, QLD, Australia
Registered: Sep 2001


 - posted 05-18-2002 04:31 AM      Profile for Matt Close   Author's Homepage   Email Matt Close   Send New Private Message       Edit/Delete Post 
Randy, thanks for your advice. I will do all that you mentioned. One thing though, I usually just check diodes with a multimeter.... How does one check to see if it is 'going out of spec'?

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Randy Stankey
Film God

Posts: 6419
From: Erie, Pennsylvania
Registered: Jun 99


 - posted 05-18-2002 12:52 PM      Profile for Randy Stankey   Email Randy Stankey   Send New Private Message       Edit/Delete Post 
You can check diodes with an ohm meter. It should have high resistance one way and almost no resistance the other. The actual values vary depending on the type of diode used. I don't remember the values by heart. I'd have to look them up again because it's been so long since I checked a diode that way.

The other way is to use the "diode check" function that some meters have. They give you a reading based on how much current flows through them. (or whatever) The diodes that we used in the CFS consoles would read .300 to .500 on the meter. If they were getting to low we would change them even if they still worked.

Whatever method you use, the values aren't exactly set in stone. For me, it's more an experience thing. You might get a diode that reads .499 on the meter and it would be good but if you got one that read .299, it's still good but it's a little low. I might replace it but it depends on conditions. Let's say the machine is really hot. You'd give a little leeway there and keep a diode that reads a bit low. On the other hand, if the machine was cold, a diode with the same reading would get changed.

The best way, in my opinion is to keep a mental record of the readings you take, compare them with readings of ones that you know to be good and make decisions based on that experience.

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