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

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Stereo Cell Alignment Issue- (Page 1)

This topic comprises 2 pages: 1  2

Author Topic: Stereo Cell Alignment Issue- Bill Duelly Film Handler Posts: 92 From: Roselle Park, NJ Registered: Feb 2006 posted 02-20-2009 08:26 PM                     I have a Sony DFP 3000 Processor, JAX light and stereo cell in a RCA 1040 sound head. When running Dolby Tone, the level on the right channel seems to bob up and down a bit, but the left channel seems fairly steady. When I think I have it up to an average level, and then put a reel on, it appears that the right channel could be a few hashmarks weaker. As it is, the gain diffrerence between the two is about 2.0 DB. Also as an FYI, it is aligned for minimal cross talk as well. Could this be a sign of one side of pickup cell going bad? (I also checked to make sure the lens optics were clean. Also, there is a new LED array in the JAX light so it shouldn't be that) Or could there be something else at play? Anyone else ever come accross this?  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 02-20-2009 08:32 PM                     you might have some oil in that slit lens that could be an issue. Have an extra slit lens around to swap out and try? Big problem with the Jaxlight on existing slit lens/photocell assemblies is that the lens and photocell originally work together to accomodate the full light spectrum of the white light from the exiter lamp. The emissions from the red LED of the Jaxlight isn't strong enough to go through the glass elements of the slit lens and the cell isn't sensitive enough for red light frequency as for normal full spectrum white light. Thus, you're only getting half of what's needed. -Good luck -Monte  |  IP: Logged Bill Duelly Film Handler Posts: 92 From: Roselle Park, NJ Registered: Feb 2006 posted 02-20-2009 08:58 PM                     The only other slit lens I have is a wider mono one. I heard tell of opening a lens to clean it. Is it a difficult process?  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 02-21-2009 03:46 AM                     Sorry, can't answer that one on how one would take apart a slit lens assembly outside of sending them to your supplier who knows where to send them in for professional cleaning.  |  IP: Logged Marin Zorica Jedi Master Film Handler Posts: 671 From: Biograd na Moru, Croatia Registered: May 2003 posted 02-21-2009 04:57 AM                     First clean all optics including cell, I did have seen some small damage to cells but they still performed well. Are this happened before or, maybe something is wrong with wiring or grounding on that channel?  |  IP: Logged Ken McFall Jedi Master Film Handler Posts: 615 From: Haringey, London. Registered: Apr 2001 posted 02-21-2009 09:40 AM                     Jax lights are awful and very critical to align to get the most out of them. You may well find that the uniformity is.... will be, poor. Get a loop of some CAT506 uniformity test film. Feed the left and right test signal from the processor into one channel of your analyser and feed BOTH left and right test signals from the processor in to it. You should ideally see six peeks representing three signals on each channel from your processor. The aim is to get the peeks all the same hight so that the film is illuminated evenly across both channels. You may find you have to shim the Jax light on the inside, outside, rear or front or a combination to get the best results possible. As for you having a mono lens tube I'm not heard on one before. I'd give it a try and run some buzz track. You should be scanning to the maximum width without any signal from the edges of the sound track. It's a time consuming job to experiment with different parts and having to re do the a chain each time but it may reward you with an overall better sound. If all else fails dump the Jax light!! Regards.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 02-21-2009 11:27 AM                     I don't think one can take a slit lens apart Put a scope on the output and see if the level fluctuation you are seeing is the dolby tone or background noise then reverse the cell connection at the jax light preamp and see if the problem moves  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 02-21-2009 03:06 PM                        Many of the old B&L lenses unscrewed. I haven't unscrewed an RCA lens, but they are all build alike. Be sure to reseal! BTW: the only good Jax lite is one in a museum, that is not powered up. Louis  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 02-21-2009 03:14 PM                  Why do so many people put down JAXlights? It seems like a viable solution to the cyan track issue. I'm not particularly fond of their preamp... I think it sucks. But properly modified, it works great. Please be specific in your pro and/or con comments.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 02-21-2009 03:18 PM                     I believe that Ray Derrick made a modified preamp for them down in Oz The Led source is by itself more than clever  |  IP: Logged Bill Duelly Film Handler Posts: 92 From: Roselle Park, NJ Registered: Feb 2006 posted 02-21-2009 04:35 PM                     I did give things a thorough cleaning today, having to pull the lamp socket out to get to the back of the slit lens. When I put it back in, I had to readjust (raise) the levels. The right side still needed more gain, but it did seem more stable. We'll see. BTW, I had also reversed wiring like Gordon suggested and it is NOT the pre-amp.  |  IP: Logged Bill Enos Film God Posts: 2081 From: Richmond, Virginia, USA Registered: Apr 2000 posted 02-21-2009 06:50 PM                     Make one of Jeff Strickler's homebrew red led replacements. We made two of them and used them for 3 years without having to touch anything. They seem to be brighter than the Jaxlight and have a wider angle and covered the slit lens completely. They were eventually replaced by BACP reverse scans.  |  IP: Logged Kenneth Wuepper Phenomenal Film Handler Posts: 1026 From: Saginaw, MI, USA Registered: Feb 2002 posted 02-21-2009 10:09 PM                     Bill, Try looking at a Dolby installation for the A chain alignment. There you will find a simple way to "see" the light coming through the slit lens. Perhaps that will simplify your alignment as well as answering your question of coverage of the track. In the CP-55 manual in the manuals section of this site you can see this process in the 4.4 section of drawings. Hope this helps. KEN  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 02-21-2009 11:58 PM                     Dang,forgot about that old 'paper trick' to see the filament display..that would work.  |  IP: Logged Bill Duelly Film Handler Posts: 92 From: Roselle Park, NJ Registered: Feb 2006 posted 02-23-2009 09:02 AM                     Well those tips have offered some guidance to go further as well as jarred the memory. I may be on to the root cause of all things evil in this setup... A little history first to set this up. About 10-12 years ago, the soundhead was at the old Rangertone to modify for stereo. The put a newwcell in, but for the narrower slit lens, they did NOT use one for the 1040 but took another on that was short & stubby. Doing so, they took off the tightening knob and put in a new lock down screw on the side. It is aslo apparent that they did some minor boring to that lense hole. With the bright incadessent, there was always plenty of light to work. When the JAX went in, the short lens was NG for generating enough light. So I was able to obtain a proper slit lens. I installed and aligned using the scopes, but after contantly doing that, it never really seemed to hit the perfectly clear sound. So after very careful study this past weekend, what had happened was that after I hit the right spot on the scopes, and then tightened, the tightening process (with their new set screw) was actually rotating the lens ever so slightly (changing azimuth) and with the wiggle room, was also shifting it horizontaly so it was giving weaker signal to the right channel area. Sooo.. it will be some work to shim the lens so it won't shuffle in the next alignment. It at least looks like I may be on the right path. As always, gentlemen, thank you for your assistance!  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 2 pages: 1  2

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.