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Author Topic: Help with dolby digital problem, CP500, Cat. 700 Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 11-08-2003 07:13 PM                        Here's the scoop, We have a CP500 and a cat 700 reader that has been getting gradually worse over the last few weeks. I have tried swapping the reader with a known good cat 701, and the results are about the same. tried a new bulb, raise the video level to 4V p-p and it still isnt tracking for shit. Need help, thanks, Josh  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 11-08-2003 07:23 PM                     Have you tested the system with a known, good source of SR-D data?  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 11-08-2003 07:46 PM                        Yes, we ran a selection of trailers through as well as test loops, movies we are currently running, and such. We have also tried a different reader. JJ  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 11-08-2003 08:03 PM                     Assuming that you have a good link between the reader and processor, I think you are now left with a suspect processor component, which means board-swapping if you have another unit that is working. But first, I recommend going back and performing a textbook calibration of the reader. This means running a loop of calibrated Dolby film and aligning the reader with DRAS.  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 11-08-2003 08:48 PM                        We'll do, thanks. Josh  |  IP: Logged Matt Zeiner Expert Film Handler Posts: 146 From: Windsor, CT USA Registered: Sep 2003 posted 11-09-2003 01:32 PM                     What kind of projector is it with what platter? I have seen all sorts of mechanical problems that lead to excess jitter. How does the right hand goalpost look? I had an Ernemann once that had a good-looking signal, but something was exciting a mechanical oscillation that caused jitter that made DRAS read OK (low jitter reading), but jitter was clearly visible on the goalpost. Turned out that the main drive belt was too tight causing the entire projector to oscillate. Seen similar problems with Century shutter shaft bearings, and also with poor film path alignment with Potts-type platters.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 11-09-2003 02:36 PM                     It may not only be the projector, but the CP500 as well. Joe and I did a test before where we ran a loop of film through a CP500 and noted the readings, then without changing anything on the projector, hooked the reader cable into a DA20 and got noticeably better results, to the tune of a couple error points. A cat700 by definition will track better than the cat701, assuming both are calibrated properly. Did the CP500 ever track well in the past?  |  IP: Logged John McConnel Expert Film Handler Posts: 118 From: Okmulgee, OK USA Registered: Nov 2003 posted 11-10-2003 02:37 PM                        Brad, You mentioned that a Cat. 700 tracks better than a 701. How does the performance of a Cat. 702 compare?  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 11-10-2003 02:48 PM                     702 tracks better than the 701.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 11-10-2003 03:40 PM                        Out of curiousity--how does SRD deal with speed variations? Is it possible that the projector isn't running at the proper speed or is varying in speed over the course of the show? Is the projector equipped for variable-speed operation (for silents, etc.) and, if so, is the speed locked to 24fps? Does the electric power in the theatre vary by time of day? In Providence, RI, the voltage always goes up slightly at about 8:00pm, which affects the feed speed in arc lamps. Maybe there's something like that going on. Try putting the CP500 on a UPS for a show and see what happens. I'll second the possibility that the processor (or cards) may be an issue. At the 6-plex we have three sets of SRD cards which rotate among auditoria depending upon what films we want to play in digital. Swapping the cards with a different set can have a noticeable effect on the SRD error rate, even with the same print and reader (CE basement readers in Simplex 5-Star soundheads).  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 11-10-2003 06:30 PM                     The cat 702 has the same scanning correction facilities as the BACP penthouse. Hint-Hint! Mark  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 11-11-2003 12:37 PM                        The projector is a Simplex 35/70, 70's vintage. we are feeding it with a christie platter. I took the 700 home and put it on my machine which has a DA20, and it was tracking 1's and 2's, so the reader is ok. Its card swapping time. Josh  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 11-11-2003 01:18 PM                     Scott -- I don't recall the exact figures but the issue of film speed during SR-D playback operation came up at the Dolby seminar in Boston. Dolby Digital is quite forgiving in terms of correcting for playback speed. Odds are good that someone on Film-Tech knows the exact min/max range of fps for SR-D.  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 11-11-2003 04:12 PM                        actually, its in the manual. It can be flexible because the internal processing speed can change to compensate for playback speed issues. That is why the CP500 has a bitrate coverter card in it. Josh  |  IP: Logged Josh Jones Redhat Posts: 1207 From: Plano, TX Registered: Apr 2000 posted 11-11-2003 09:29 PM                        Just an update. I brought by cat 675 card downtown today to see if I could locate the problem. I didnt, so I took all the interchangeable cards home and stuck them into my DA20. one of the DSP cards began to freak out, the leds flashing randomly at all times. I swapped it with one of mine and its tracking 1's and 2's. We are now in the process of ordering a new cat 671. Thanks for all the suggessions guys. Josh  |  IP: Logged

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