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Author Topic: Dolby Cat 701 roller and guide adjustment Frank Dubrois Jedi Master Film Handler Posts: 896 From: Cleveland, OH Registered: Mar 2005 posted 02-01-2007 06:36 PM                    How are the rollers or guides adjusted for tension? I think our guides have too much tension on the film causing it to go into failure. I have looked at the manual, and see a couple arms inside the cat 701 unit that look like they can be adjusted, but I was wondering which screw to loosen for the adjustment, and do I have to adjust both arms, or just the one I suspect is causing the problem. Any help would be appreciated. Thanks!  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 02-01-2007 06:41 PM                        You absolutely MUST have enough film tension to positively lock the film on the drum. With slippage you get faults and film damage. Louis  |  IP: Logged Frank Dubrois Jedi Master Film Handler Posts: 896 From: Cleveland, OH Registered: Mar 2005 posted 02-01-2007 06:55 PM                    Is there such a thing as too much tension? I noticed a film playing with an error rate that went from 5 to F or from 4 to F or from 7 to F, but when I lifted the upper arm, the error rate stayed around 4. It made me think that possibly there is too much tension on the film.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 02-01-2007 07:00 PM                     Frank, Assuming this is just a normal wear thing.... You either have a worn lateral guide roller(the one with flanges) or low video level... or both. A worn lateral guide roller is easy to spot... look for a raw alumnium edge...usually the inner edge opposite the sound track. It sticks out like a sore thumb. This allows film to weave back and forth sometimes going out of range of the CCD sensor... so when it drifts back in you get a pretty low reading and when it drifts out of range you get an "F". Simply installing a new roller brings them back spot on every time... at least when someone else hasn't tinkered with them. ALSO... If you remove the flanged lateral guide be sure not to loose the spring washer and spacer washer that are behind that inner bearing on the roller! They tend to stick to the bearing and then drop off on the floor. Naughty Frank...! What ever you do don't mess with the tension or back side lateral guide adjustments. You'll have to return the reader you tinkered with to Dolby to have it properly re-set. Setup your at least 60mhz scope and laptop in the appropriate manner and diagnose it properly!! Mark  |  IP: Logged Frank Dubrois Jedi Master Film Handler Posts: 896 From: Cleveland, OH Registered: Mar 2005 posted 02-01-2007 07:53 PM                    quote: Mark Gulbrandsen Naughty Frank...! What ever you do don't mess with the tension or back side lateral guide adjustments. I didn't. I looked at it, and thought I better ask before touching anything back there. i will look for the worn parts.  |  IP: Logged Cameron Glendinning Jedi Master Film Handler Posts: 845 From: West Ryde, Sydney, NSW Australia Registered: Dec 2005 posted 02-01-2007 11:08 PM                     quote: Mark Gulbrandsen or low video level... Every now and then you have to replace the bulb, has it been changed recently?  |  IP: Logged Frank Dubrois Jedi Master Film Handler Posts: 896 From: Cleveland, OH Registered: Mar 2005 posted 02-01-2007 11:52 PM                    The LED is new. There is no consistant error rate with this unit. It can play fine for a part of the movie, in the 3's or 4's, then all of the sudden goto F for no apparent reason. This has happened for several different movies we have had there.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 02-02-2007 09:13 AM                     Setup your at least 60mhz scope and laptop in the appropriate manner and diagnose it properly!!  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 02-02-2007 09:54 PM                     ...Yeppers, like I gotta do with 14 CAT-70x units in my area - replace all 14 sets of rollers that I just received from Dolby. Each of these units have badly worn upper lateral guide rollers with raw, sharp-edged metal flanges to where one can easily move the film across the drum to get a good error count and stop the "4 to F" readings. quote: Mark Gulbrandsen If you remove the flanged lateral guide be sure not to loose the spring washer and spacer washer that are behind that inner bearing on the roller! They tend to stick to the bearing and then drop off on the floor. ...and make sure that you have the right sized snap ring pliers to take that snap ring off that holds all of this on that shaft...and be careful because those snap rings love to disappear when they fly off the tips of the pliers when not properly seated on the tips.. - Monte  |  IP: Logged Frank Dubrois Jedi Master Film Handler Posts: 896 From: Cleveland, OH Registered: Mar 2005 posted 02-04-2007 12:53 AM                    How long is a set of these rollers supposed to last? Any clue as to how expensive a set of rollers are? also, I'm curious if the washers and end clips are something a hardware store might have? I think they were 1/4" washers? One flat, one curved and then the end clip.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 02-04-2007 03:33 AM                     quote: Frank Dubrois How long is a set of these rollers supposed to last? ..it's all related to the user on how he takes care of things. If a user doesn't use the proper gap space inbetween the two rollers and let the rollers run on to each other while the film is in motion for a week, it pretty well toast for these rollers. Yet, what is good is that if the gap collapses like if a bad splice or something to let the film jump off of the large register sprocket, one just opens up the upper roller, pull on the film slightly to back the film one sprockettooth and then close the assembly,while the film is still in motion, this allows the proper roller gap to be reset. Done this trick many times. Granted, when the film runs out of the assembly, the rollers do snap into each other, thus there is actually no total preventiveness in this snap closing technique..unless the user is right there when the film runs out to catch this assembly before they snapclose, then they can last quite the long time. -Monte  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 02-07-2007 03:17 AM                     UPDATE: After doing a roller changeout on 14 readers, the error count drastically changed from between 7.5 and F, clear down to a good solid 5 on majority of some readers. .. and I did get some 1.5's to a settled-in 3's on rare occasions with some other readers.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 02-07-2007 03:13 PM                     Thats still pretty high if you ask me. 1. to 3. would be normal for new film with some running at 1's and 0's these days. I think you just need to fine tune your technique. Mark  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 02-07-2007 09:20 PM                     Oh, I do agree with you Mark, but when most of these houses run used film, one can wonder on how the condition of the prints. thx-Monte  |  IP: Logged Frank Dubrois Jedi Master Film Handler Posts: 896 From: Cleveland, OH Registered: Mar 2005 posted 02-13-2007 01:03 AM                    didnt fix the issue...  |  IP: Logged

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