Film-Tech Forum ARCHIVE: Help with dolby digital problem, CP500, Cat. 700

This is topic Help with dolby digital problem, CP500, Cat. 700 in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Josh Jones (Member # 447) on 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

Posted by Manny Knowles (Member # 1171) on 11-08-2003, 07:23 PM:

Have you tested the system with a known, good source of SR-D data?

Posted by Josh Jones (Member # 447) on 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

Posted by Manny Knowles (Member # 1171) on 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.

Posted by Josh Jones (Member # 447) on 11-08-2003, 08:48 PM:

We'll do, thanks.

Josh

Posted by Matt Zeiner (Member # 1914) on 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.

Posted by Brad Miller (Member # 2) on 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?

Posted by John McConnel (Member # 2000) on 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?

Posted by Brad Miller (Member # 2) on 11-10-2003, 02:48 PM:

702 tracks better than the 701.

Posted by Scott Norwood (Member # 30) on 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).

Posted by Mark Gulbrandsen (Member # 72) on 11-10-2003, 06:30 PM:

The cat 702 has the same scanning correction facilities as the BACP penthouse. Hint-Hint!

Mark

Posted by Josh Jones (Member # 447) on 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

Posted by Manny Knowles (Member # 1171) on 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.

Posted by Josh Jones (Member # 447) on 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

Posted by Josh Jones (Member # 447) on 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

Posted by Paul G. Thompson (Member # 655) on 11-11-2003, 10:58 PM:

Although you have a heart of gold, Josh [Smile]

- I don't think it is a very good idea to use your personal private equipment to troubleshoot other theater's equipment.

If you blow up the theater's equipment in your equipment, you could be held liable. If you blow up your equipment by using it in the theater equipment, you could just simply be up the creek without a paddle. Unless you have a spare 1,000 bucks to replace your personal equipment, I would recommend you let the theatre fend for themselves just like they would probably let you fend for yourself if you damaged your equipment in their equipment.

Been there....

That's just the way it is. I am very sure others on FT could relate horror stories to you because they wanted to be a "nice guy" and help the theater out and it backfired on them.

The bottom line is: Protect your own ass at all times!!! [thumbsup]

Fourty years ago, this would have never be a problem. Unfortunately, that was then and this is now. [Wink]

[ 11-12-2003, 12:04 AM: Message edited by: Paul G. Thompson ]

Posted by Phil Hill (Member # 371) on 11-12-2003, 12:43 AM:

quote:
Protect your own ass at all times!!!

I certainly do not agree with that. If everyone believed in that philosophy, nothing "good" would get done.

Paul is very much on target about NOT using one's own personal property to "help out" an employer. While the gesture may be a noble one, the consequences can sometimes be not beneficial to either party.

I too have been burned big-time by my "generosity" that then evolved into "expected". I STILL haven't got all my personal (many $K) stuff back from ...Ummmm... you-know-who! [evil]

It was "conveniently misplaced or out at a site. [fu]

>>> Phil

Posted by Paul G. Thompson (Member # 655) on 11-12-2003, 01:02 AM:

Phil, I stand by my statement. [Smile]

You didn't keep your butt covered....and you lost. You got burned because of your generosity. That's what I was referring to. The same thing happened to me.

I lost a Brenkert by loaning it to keep the theater running. The operator ran it out of oil and ruined the movement. The theater owner at the time said, "Tough Shit. It was not the company's machine."

I ate it.

Posted by Phil Hill (Member # 371) on 11-12-2003, 01:09 AM:

That's true Paul, but I still lived...I didn't die. I think the risk in many cases far outweighs the down side in taking a chance and helping "someone" or a company/theatre out.

And when I couldn't recover my property, it was a tax write-off. We all learn to make more "enlightened" decisions as time goes on.

I still stand by my philosophy...Josh did the right thing. [Smile]

>>> Phil

Posted by Manny Knowles (Member # 1171) on 11-12-2003, 01:13 AM:

quote:
If everyone believed in that philosophy, nothing "good" would get done.

Nothing "bad" would get done either. [Big Grin]

I could add to the long list of tales about how companies will let you do for them what they would never do for you if the shoe was on the other foot.

Don't you *ever* do that again, Josh! [Big Grin]

Posted by Paul G. Thompson (Member # 655) on 11-12-2003, 01:15 AM:

Thanks for your re-enforcement, Manny. [Smile]

Phil, are we both Norwegian? [Big Grin]

Posted by Josh Jones (Member # 447) on 11-12-2003, 01:27 AM:

I think you guys are getting a little carried away. I have a little more faith in my boss and friend for that matter, than anyone else in the building. In the instance that some of my equipment was damaged, I would indeed raise holy hell until the situation was rectified. period. But in a situation like this were it litereally couldnt get any worse, I have little to loose.

Josh

Posted by Brad Miller (Member # 2) on 11-12-2003, 01:30 AM:

I can't believe I am reading this.

Guys, it's a judgment call. If Josh was working for some megaplex that treated him like a number, I would agree not to bother as his efforts would not be appreciated nor noted. However that is not the case here and I seriously do not think his current employer would have screwed him. What Josh did was solve the theater's problem in a speedy manner that even a high dollar service tech may not have been able to. Any quality employer can see that and few employers are lucky enough to have someone that cares that much about their job to go to so much trouble for them.

If nothing positive comes out of helping the theater, or if something bad was to happen, that's just what happens and it becomes a learning experience that sticks better than being simply told stories from someone else's misfortune in the past. Personally I have bent over backwards for theaters in keeping them running and have never gotten screwed. Those that showed no appreciation for my going above and beyond to help them, I simply did not go out of my way to help in the future.

Besides, it is his equipment and as such it is his decision, not anyone else's. Only Josh knows the relationship between him and his employer as well. Personally I am shocked to see you guys publicly scolding his generosity and desire to help. If the need to dictate to him how he must handle his life is that important to you, at least have enough tact to do it in private and not on the internet to embarass him in front of the world. That's pretty shitty in my book.

I am closing this thread because the problem has been solved and to prevent any more of this nonsense.

Posted by Manny Knowles (Member # 1171) on 11-12-2003, 01:30 AM:

Here it is...from the Great Big Book of Boys' Names:

quote:
Josh...from the Greek, meaning "more looks than brains."