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Author Topic: Projection Q&A Peter David Bruce Expert Film Handler Posts: 187 From: East Anglia -England Registered: Aug 2007 posted 11-23-2007 05:04 PM                    Ok, so im new to projection... learning fast! How do you 'see' the xenon arc? i presumed i shouldlook for something in the bulb through the viewhole but nope.. i am probably being very naive with this.... a nice explanation would suffice! Where is the rectifyer located (approx) and what does it do (precisely)? Anybody know a surefire way to eliminate vertical movement of the frame when running a film? I adjust the frame tension straps with the side screw and this helps a fair bit, but on still scenes its still slightly bobbing away... ... Really after a still image. Anybody know of any good brain units? We use bog standard lace-it-up-yourself ones that are simply a piece of metal with the rollers in the right place. Often we get loops of film caught up in it while doing ad/trailer changes... Is there a better brain unit I can check out? Its a constant battle against brain wraps and we have to stand by it and physically pull the film out of the way if it gets caught up.... Thanks everyone... ill use this topic to pose any future questions. As I say, im learning here and im going to have lots of questions! Cheers Peter  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 11-23-2007 05:14 PM                     "How do you 'see' the xenon arc? i presumed i shouldlook for something in the bulb through the viewhole but nope.. i am probably being very naive with this.... a nice explanation would suffice!" It is impossible to see the plasma in the lamp but it is possible to see the arc between the electrodes. You can't miss it! _______________ "Where is the rectifyer located (approx) and what does it do (precisely)?" It can be located just about anywhere one wants to place it. It converts AC to DC. ________________ "Anybody know a surefire way to eliminate vertical movement of the frame when running a film? I adjust the frame tension straps with the side screw and this helps a fair bit, but on still scenes its still slightly bobbing away... ... Really after a still image." You need to discern if the bobbing is in the print or from a malfunction of the projector. You need a piece of film like RP-40 thats camera original to test the projector with. If this film is steady then the print is at fault and there is not really anything you can do about it except request another print.... which will also probably have some bounce to it. _____________________ "Anybody know of any good brain units? We use bog standard lace-it-up-yourself ones that are simply a piece of metal with the rollers in the right place. Often we get loops of film caught up in it while doing ad/trailer changes... Is there a better brain unit I can check out? Its a constant battle against brain wraps and we have to stand by it and physically pull the film out of the way if it gets caught up...." It sounds like you need to install wrap detectors to shut the system down when a brain wrap happens. A picture of your "brain" would really help us to see what the problem is exactly... also, what make of platter system is it? Hope this helps. Mark  |  IP: Logged Peter David Bruce Expert Film Handler Posts: 187 From: East Anglia -England Registered: Aug 2007 posted 11-23-2007 07:09 PM                    right, so the actual bright light i can see in the middle of the bulb is the arc? its such a small bright light, its impossible (i think) to see how its curving! Ah right... ac to dc. i think im clear on where that is... is the 3-phase thingy nearby or built in... i keep hearing people talking about checking the ratings on the three phase power to solve flicker... ? I am running RP40s again next week, so I will have to see how it looks then. fingers crossed its just the print! Wrapping... well im not sure I just want to stop the projector if it starts to wrap... cos im fine with fixing it as it happens (get my hands in there). Rather than interrupting the showing. below is a pic of my brain unit. Our platters are by Strong - its model is the AP3. PICTURE REMOVED BY MODERATOR - ALL PICTURES MUST BE UPLOADED TO THIS WEBSITE TO MAINTAIN THE INTEGRITY OF THE FORUMS - NO OFFSITE PICTURE LINKING IS PERMITTED [ 11-23-2007, 09:35 PM: Message edited by: Brad Miller ]  |  IP: Logged Chris Slycord Film God Posts: 2986 From: 퍼항시, 경상푹도, South Korea Registered: Mar 2007 posted 11-23-2007 09:42 PM                     It actually takes quite a large amount of wrapping from what I've seen to get the wrap detector to engage; at least at my cinema and we have the same platters. Though, I've really only seen the detector engage while threading/lacing the projector and pulling film through really fast. Guess we're lucky to not have it wrap often. Furthermore, I don't see why you'd be against the wrap detector. On the chance that no one's sitting up there constantly staring at the brain, the wrap detector avoids the chance of further damage to the film. Obviously, if the wrap gets bad enough the print will stop and get melted/torn up. With the wrap detector, you're less likely to get that. Also, you don't really have a choice of what kinds of brains to use; the strong platter works with the brain you're using and any others will not work whatsoever. Like if you used a christie brain it's bottom peg wouldn't fit and wouldn't have the electrical connector the strong platters use (since christie platters brain is just mechanical; the controller is completely separate). Small note: There's no "curving" to see in the zenon. One of the meanings of arc is "a luminous bridge formed in a gap between two electrodes. Also called electric arc."  |  IP: Logged Cameron Glendinning Jedi Master Film Handler Posts: 845 From: West Ryde, Sydney, NSW Australia Registered: Dec 2005 posted 11-24-2007 02:47 AM                     Hi Peter I have a few questions Do you work with anyone else or are the the only operater there 24/7? Is it a part time operation? How many screens? What brands are labeled on the projectors, the cakestands/platters are strong ( , and sound equipment? Bulbs can flicker due to old age, irregular power from the powerpoint, AC ripple in the rectifier, wrong voltage for the bulb, or even cheap or defective bulbs, perhaps the bulb conections are not tight enough. there are many other possibilities. Lets start with the brand of bulb, how many hours or months/years has the bulb been in the projector? quote: am running RP40s again next week, so I will have to see how it looks then. fingers crossed its just the print! As for the test film, um a quicker way to cheack migh be answered with this question. Does the bounce happen during the ads and trailers at the begining? do you have any other film in the box you could run, if the bounce is consistant on all movies, ads & trailers your problem is with the projector. If its just one or two movies/ads its the lab.  |  IP: Logged Peter David Bruce Expert Film Handler Posts: 187 From: East Anglia -England Registered: Aug 2007 posted 11-24-2007 04:07 PM                    i do work with a second projectionist, but our hours are split 70/30 to me. its good having him around but it leaves me to do 90% of all the maintenance... its a full time operation - 6 screens - our projectors are Century MSC-TA and the lamphouses are Strong Highlight II. Not sure about the brain unit makes... I presume strong as our platter units are strong model AP3. Sound equipment: processors are Dolby CP45's (3 smaller screens) and CP650's (3 biggest screens). amps are Ashly FTX Series III. CD decks comprise of various makes, mostly Denon. The bulbs we use are Osram XBO 3000 W/HS OFR (thats 3000watt). We use the XBO 2000watt on smaller screens. Since being installed about a month ago, screen 4, it has done only 180 hours and is in need of being stepped up soon (something i plan to do tomorrow morning). The bounce seems to be constant throughout the ads trailers and film. Hence why I was looking at a mechanical issue....? I will be running a kids showing tomorrow morning of Elf so will see if the bounce occurs on that showing too. Hopefully as you say it could be the Lab making somewhat iffy prints. I have a dolby Jiffy loop i can run sometime next week. Always good to spot this kind of thing, plus also lets me enjoy the capabilities of our sound system! Second query - THIS IS ODD - I have just closed down projector 6... its been running Stardust there for over a week now. I go to cover the platter up for the night and I noticed that it hasnt plated back on properly... its all loose and you can squash the print inwards if you push the edge.. its just not plated back on tightly. You can see the first half of the print is fine, but the rest is all loose. Im running it again tomorrow morning - should I just wait and see?  |  IP: Logged Ben Wales Jedi Master Film Handler Posts: 602 From: Southampton. England Registered: Jul 99 posted 11-24-2007 04:40 PM                     Peter: Have you discussed some of your "Picture Issues" with your Service Tech Mr Mort?.  |  IP: Logged David Graham Rose Expert Film Handler Posts: 187 From: Cambridge, UK Registered: Sep 2002 posted 11-25-2007 04:53 AM                     Greetings Your problem stems from the use of crappy Osrams. David  |  IP: Logged Peter David Bruce Expert Film Handler Posts: 187 From: East Anglia -England Registered: Aug 2007 posted 11-25-2007 05:52 AM                    Wow, David... you think so? Weve been using them for years and they always seem to do a good job... I guess I may have just stumbled on a bad bulb this time around, but still... very good track record. Whats your experience with them? Also, can you offer any advice on the platter issue ive just mentioned? It seems to be doing it again this morning...  |  IP: Logged Cameron Glendinning Jedi Master Film Handler Posts: 845 From: West Ryde, Sydney, NSW Australia Registered: Dec 2005 posted 11-25-2007 04:27 PM                     quote: can you offer any advice on the platter issue ive just mentioned? It seems to be doing it again this morning... [Frown] I think it might just be an issue with the print, The few times this happens to me, I tend to take up the print upside down. ie soundtrack down if you usually take up soundtrack up, on the plate. This may allow the print to take up better for a while. If its more than just one or the ocasional print see, your service tech! Osram can have quality control issues in my recent experience. My suggestion is to change the bulb, make sure the connections to the bulb are tight. If the problem persists its probably the rectifier. If its gone, it was the bulb and can be replaced under warranty by osram. As for the bounce, it sounds like you need a serve tech to look at your machine.  |  IP: Logged Scott McGuire Film Handler Posts: 94 From: Elmira, NY/United States Registered: Oct 2007 posted 11-26-2007 12:47 AM                     Have had a print take up like that on two occasions, both were because of sprocket damage to the pring. One was from a loose pad roller and the other i think was froma miss thread as there were no loose pad rollers in the projector. Also once this damage occured the print did not take up right from that point on.  |  IP: Logged Emma Tomiak Expert Film Handler Posts: 238 From: Carrollton, TX, USA Registered: Aug 2003 posted 11-26-2007 05:44 AM                        Scott's right, Peter, you've got perf damage. And, at least in my experience, the print will always have it and take up oddly. I call it "mushy syndrome". Taking it up soundtrack down really won't help, and could end up doing more damage than good. You're just stuck with the mushy print. Filmguard it well and give your projector (and threading methods) a thorough going-over to find out what caused the damage.  |  IP: Logged Peter David Bruce Expert Film Handler Posts: 187 From: East Anglia -England Registered: Aug 2007 posted 11-26-2007 08:53 AM                    It seems (after just taking a call from my colleague) that we might have a loose pad roller in the projector. I will only be able to check this in the morning, but apparently its been running ok on and off all morning. Cant vouch for this as im not there today to see for myself. I think that this happened due to poor lacing up by my colleague the first time around. first time it happened, he had rushed the laceup and caused incredible tension to the rollers (far too small loops!). He had to stop the showing half way through to relace. I believe the pad roller in question has become loose due to the tightness of the film before he got there to stop it. Hopefully i can just tighten the screw and we wont have any more problems... but its been running badly for a few days now so the damage may be done. as for the bulb... ive had to up the amps twice now recently and now its looking STUNNING. really good. Didnt expect to have to increase the amps JUST yet.... but either way im getting a good picture now. The bobbing im seeing on the film is so minor I may get away with it for a while. we ran a different film on the screen recently and even though the bobbing was still there, it was less than in american gangster. so... not a bad result there. I will attempt to organise a full tech inspection for the new year. thanks everyone. I really appreciate all the help. next thing.,.. aperture plates. ok, so they are all worn due to age. they ARE only copper after all! but on some of our screens the wear is so bad we are projecting over a foot off the edge of the masking, at the sides and top! I suppose the only thing to do is get new plates?  |  IP: Logged Kenneth Wuepper Phenomenal Film Handler Posts: 1026 From: Saginaw, MI, USA Registered: Feb 2002 posted 11-26-2007 02:39 PM                     Peter, The aperture plates don't "Wear Out" making bigger openings for the light to pass through. They are carefully fitted with a file to change the openings. Wear can sometimes make the plates sloppy and then the registration will be off on one side or the other but not both at once. I believe that the focus of your light source may be causing the problem. If the lamp is spreading the light far beyond the edges of the aperture there may be an enlargement in the image being projected. Since the image on the screen is too big OVERALL, I would suggest properly focusing the lamp before making any drastic changes in the aperture plates. If the picture was right once, it will be something besides the plates causing this over-sized image. KEN  |  IP: Logged Peter David Bruce Expert Film Handler Posts: 187 From: East Anglia -England Registered: Aug 2007 posted 11-27-2007 04:55 AM                    ok after closer inspection (and chatting to the old proj. boss) it seems he had filed down the edges in the past in order to remove any edge fuzz... and unfortunately it seems he went a bit overboard on that particular screen! i will play with the focus anyway and see what i can do. running the rp40 tests today so i will get it as good as i can today.  |  IP: Logged

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