my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Digital Cinema Forum   » Blue and Red light leak after swapping Light Engine

Author Topic: Blue and Red light leak after swapping Light Engine Nat Jencks Film Handler Posts: 9 From: Brooklyn, NY, USA Registered: Apr 2019 posted 05-01-2019 11:30 PM                        We just swapped a light engine on a new DP4K-19B and after the swap we are seeing much more light leakage coming from the front of the lens including some blue and red leaks that look like they are from the prism. In our setup there is a foam core divider in our porthole. Prior to light engine swap there was *NO* light hitting this divider and now you can see a big circle of light with clear red and blue spillage. Does anyone have any thoughts or clues about this? The tech that did the swap noticed that the design of the light engines was slightly different with the newer one having two holes in the front of the light engine. Waiting for more info from Barco. Anyone seen this issue? Thanks! -Nat  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 05-02-2019 03:17 AM                     I struggle to believe that a 4K projector won't have any residual light coming out from the engine - what you see looks pretty normal to me (besides those funny coloured spots!). Get your colour meter and measure the contrast ratio ON/OFF (make sure the auditorium is pitch black when measuring black). If it reads something around 1600/1800:1, then your engine is working well (I'm assuming you don't have a High Contrast lens). Not all engines are the same. Some are better some are worse. Take measurements to make sure they meet the specs.  |  IP: Logged Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 05-02-2019 04:28 AM                     The residual light is hard to judge from this picture, since you don't know about the exposure time. The blue and red spots are definitely not something I see in our unit and might point to a somewhat misaligned prism. The unit might still calibrate fine though.  |  IP: Logged Nat Jencks Film Handler Posts: 9 From: Brooklyn, NY, USA Registered: Apr 2019 posted 05-02-2019 08:54 PM                        @ Marcel, it looks about the same in person as it does in the picture. This is actually the third light engine for this brand new projector (don't ask). The first Light Engine which came with the projector didn't have this bright circle of light or the red and blue leaks. However BOTH of the replacement light engines which seem to be slightly differently designed DO have the issue. The attached image shows the difference between the light engines and the issue we are seeing.  |  IP: Logged Alan Gouger Jedi Master Film Handler Posts: 501 From: Bradenton, FL, USA Registered: Jul 2000 posted 05-02-2019 10:45 PM                        It's possible it looks like the folding mirror or light pipe was not properly aligned. Is there any shading issues around the corners or the edges of the screen if displaying a 100% full white raster.  |  IP: Logged Nat Jencks Film Handler Posts: 9 From: Brooklyn, NY, USA Registered: Apr 2019 posted 05-02-2019 11:03 PM                        Thanks for the reply Alan! Bear with me because my knowledge of the inside of the light engine is limited! Are the folding mirror and light pipe part of the light engine? The reason I ask is that we have seen this on two totally different light engines at this point. We are not seeing shading in the corners if we put up white. Uniformity is not perfect but its not bad. Thanks  |  IP: Logged Alan Gouger Jedi Master Film Handler Posts: 501 From: Bradenton, FL, USA Registered: Jul 2000 posted 05-03-2019 10:35 AM                        If there are no colors appearing at the edge or corners of the screen then disregard my previous comment, your folding mirror, and light pipe is not an issue.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 05-03-2019 10:55 AM                     I doubt that those openings are the culprit of the issue. Indeed when a new engine is replaced sometimes you may need to re-adjust the cold mirror but if you don't do that you'd lose light - I wouldn't expect the issue you are mentioning. I still recommend you check the contrast ratio on screen - that amount of light doesn't seem so weird for a 4K chip.  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 05-03-2019 03:33 PM                     Put some duct tape over the holes?  |  IP: Logged Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 05-04-2019 04:27 AM                     The amount of light leakage itself doesn't look entirely off, but those colored corners are simply weird and I've not seen this before. To me, it looks like a problem with the prism. But if it doesn't end up on-screen and the contrast ratios are OK, then it's probably fine to live with it.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 05-04-2019 04:49 AM                     It is normal to have "a" coloured patch on a corner of the light output - Barco has an info-T about that and the same applies for Christie. But it's usually a low level coloured patch, not what you are showing in the picture. I still feel that you should check the contrast on screen and if that checks out, you're ok. Again, remember that an emergency light in the auditorium will completely void your black level reading.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 05-04-2019 12:03 PM                     I've put in quite a few NEC 3240's and never had any light leaks like that. I even replaced two engines that were bad from the initial batch of projectors and never saw any leakage like that during convergence and set up. Mark  |  IP: Logged Paul Finn Film Handler Posts: 41 From: Bay City, MI Registered: Jan 2019 posted 05-04-2019 01:12 PM                     Sir: Please explain, if possible, the reason(s) that this is the third new light engine in a "brand new projector"? Thank you, Paul Finn  |  IP: Logged Nat Jencks Film Handler Posts: 9 From: Brooklyn, NY, USA Registered: Apr 2019 posted 05-07-2019 11:15 AM                        @ Paul Light engine was swapped because of issues hitting P3 targets satisfactorily.  |  IP: Logged

All times are Central (GMT -6:00)

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.