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Author Topic: Barco S series brightness issues Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 10-29-2015 12:06 PM                     Barco's claims are for the DMDs only. Both ends of the integrating rod, cold mirror, fold mirror, notch filter and any lenses between the lamp and the prism are open as well as the outlet of the light engine, including the lens inlet pupil. Though the light sensor readings will only notice dirt up to the fold mirror.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 10-29-2015 02:02 PM                     quote: Dave Macaulay I've never had any LE dirt problems with one. Christie and NEC, yes. Same here. Steve, All the lenses and filters inside the LE, including the integrator case, are relatively sealed. I wouldn't expect much dust going in there. One place which gets dusty is between two prisms, just before the lens end. There is a small gap between them.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 10-30-2015 07:32 AM                     Pull one down and look for yourself with an LED flash light (they tend to show the dust off very well). Heck, just look at the inlet of the integrating rod via the, likely, dusty cold mirror.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 10-30-2015 10:10 AM                     I have opened one of those in the past to replace a cracked lens and I noticed how sealed and clean the area was. A little dust visible with a flashlight does not mean that you will have a visible effect on screen. And coatings may be more important that a few specs of dust. I cleaned some very - very - dirty Dolby 3D wheels some months ago. I thought I would have a sensible increase in brightness, and in fact the difference was negligible. Contrast: yes. Brightness, unless the optics are really dusty I don't think it's a problem. That said, I always clean the reflector, the cold mirror, the integrator's face etc. etc.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 10-30-2015 12:32 PM                     I don't know what to tell you...the owner of the theatre wanted the projector cleaned...so to let myself know what the difference was, I turn the projector on and aligned the lamp...measured it (with a color meter to ensure that I was at .314/.351)...cleaned the optical path completely...measured it again and I was up 10% in brightness. All that was removed was dust.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 10-30-2015 01:12 PM                       One of the many areas you cleaned made way more difference than the others. Any guesses which surface? Sort of related to this is I have 24 solar panels on my roof. It has not rained out here since anyone can remember so I cleaned the panels with soap and water but first looked at the output on two consecutive cloudless days at the same time and the output hardly increased at all.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 10-30-2015 01:37 PM                     Steve, I was not clear, sorry. What I meant was that what's inside a Barco light engine (those lenses you mentioned after the integrator) will probably have a negligible effect on brightness and that a few specs of dust on them is not worth cleaning them. On the contrary, the prism exit, the lens end, the cold mirror and the main reflector can get quite dusty and indeed I don't struggle to believe that you can get a 10% improvement, particularly on a dusty machine. Never measured myself on a DLP to be honest. I reckon the most critical areas are the prism exit/lens end (that will also affect contrast) and the main reflector.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 10-30-2015 02:28 PM                     Sam, I think it was a cumulative effect. I tend to think those areas with smaller surface (integrating rod) are more apt to play a role since the percentage of obstruction is going to be higher than the same dust amount spread over say the area of the reflector. But that is just a guess. Marco, I agree, once the light leaves the fold mirror, there is going to be very little opportunity to get any significant dust in there until you start exiting the prism area to the lens as well as the lens itself.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 10-30-2015 02:43 PM                     I meant the cold mirror though (the one after the main reflector). I agree on the integrator's outer face but I don't think that opening the integrator compartment and clean what's inside could bring any benefits to the projector. Have you noticed lots of dust build-up in there?  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 10-31-2015 08:48 AM                     It depends on the air quality. Projector air filters can get disgusting when booth air is drawn from the cinema - not unusual due to the lamp exhausts, and it's rare to pull make-up air from outside. The cinema air is always full of dust just from the people traffic. Popper smoke is the most common serious problem. It's often not completely (or at all) exhausted, either to save money or intentionally to flood the building with "alluring" popcorn stink. Drawing air from the lobby is worse than getting it from the auditoriums where the smoke has usually dissipated. Singles and small cinemas are the worst, multiplexes usually manage HVAC properly. If I can smell popcorn stink in the booth when it's popping I know there will be some nasty cleaning to do. The tar that gets on air filters also, naturally, coats the projector optics. After needing strong chemistry to get the Barco metal filters clean once, I got curious and measured a fair color shift (by numbers, I couldn't see it by eye) after cleaning tar off the lens faces, lamp envelope, lamphouse collectors, UV plate, folding mirror, integrator entry, and prism exit face. The screen luminance didn't jump a lot though. Getting a few miles off topic but... that popcorn smoke tar can be very difficult to clean off. Isopropanol works safely on coated optics but it takes quite a while to dissolve tar. For Barco metal (or S series paper) filters the service manual procedure using sodium carbonate works well - if you have (1) boiling hot water (2) a big enough basin or sink and (3) lots of time for the filters to soak. If you like your fingerprints, wear rubber gloves. Swish 5100 cleaner is the best I've found for quickly doing the metal filters but you absolutely need good rubber gloves and a respirator would be nice.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 10-31-2015 08:54 AM                     Funny - Christie has JUST released two new support documents, one named: Christie Degrading Optical Performance Technical Bulletin The other: Cleaning Projector Optics - Carsten  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 10-31-2015 12:53 PM                     I noticed that too. Pretty much useless though. It basically says to dust the optics and if still dusty... to clean them! Oh well, there must be a reason for that. Maybe similar reason to release a bulletin to "warn" "engineers" that when swapping a Dolphin card in a Doremi server great care should be adopted to avoid scraping components off the motherboard while doing so. Ah-ehm.  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 11-01-2015 05:06 AM                     I would have thought that Acetone would be harmful to the various coated surfaces yet that is the solvent they are recommending if things don't come clean with just air. I know, once upon a time, I have used Acetone to turn colored Christmas lights clear. It will definitely dissolve popcorn tar too.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 11-01-2015 10:41 AM                     100% Acetone was always the recomendation for cleaning optics in laser light shows  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 11-01-2015 11:04 AM                     The only product that you can buy that will not scratch the coating or leave any residue or streaks from cleaning is Pancro Lems Cleaner that I mentioned earlier. It does not have acetone in it, it is non toxic. Acetone is really bad for you and you do not want to expose yourself to a lot of it. Mark  |  IP: Logged

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