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» Film-Tech Forum   » Operations   » Large Format Forum   » IMAX DTAC proj. time sound reset problem (Page 1)

 
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Author Topic: IMAX DTAC proj. time sound reset problem
Brian Michael Weidemann
Expert cat molester

Posts: 944
From: Costa Mesa, CA United States
Registered: Feb 2004


 - posted 07-21-2004 07:20 PM      Profile for Brian Michael Weidemann   Author's Homepage   Email Brian Michael Weidemann   Send New Private Message       Edit/Delete Post 
I've been wanting to pitch this problem for a while, but we kept thinking we were fixing it, and it keeps coming back ... so now I'd welcome some input. My tech has been constantly on the phone with IMAX and they are being most unhelpful.

THE SYMPTOM:
At a random point in the show, the DTAC "projector time" will reset back to 0:00:00 and run from there. The "show time" immediately finds itself too far ahead, drops out, and catches up with the new projector time, which is the very beginning of the trailer. The PLC keeps frame count perfectly and does not reset. But once the DTAC has effectively "started over", there is no way to synch it back to the console or the film.

THE FREQUENCY:
When the problem started occuring, it would happen roughly once or twice a week; random shows, random parts of the movie. It has happened twice in one day (different shows, though) and it has also gone as much as 18 days between instances.

THE CHRONOLOGY OF (ATTEMPTED) REMEDIES:
(months of periodic sound resetting)
The DTAC had its TIC card replaced with a new one.
(it happens again 6-09, and twice on 6-10)
The cable connecting the TIC card to the Sync Timing card was discovered to be bad, and replaced.
(it happens again 6-18)
A new Sync Timing card is installed, with another new cable.
(it happens again 6-28, and again 7-02)
A new "J" Module is replaced in the PLC.
(it happens again 7-20)

THE REALLY UNPROFESSIONAL QUICK-FIX:
Because the show is effectively ruined, passes and refunds are handed out, and management really hates us. So to "save" the show when this happens, this is what I've been doing. It doesn't really work, but at least we can finish the show.

Stop projector, stop DTAC, close DTAC show list, open SCREENING mode, open show list, advance to "feature" region, convert PLC frame count to hr:min:sec:frames, use the DTAC "Jump To..." and enter hr:min:sec:frames. Start projector, when projector is at full speed (about eight seconds) hit the "OK" and theoretically, the sound will start up at the same part of the movie that the projector is running at. (I did the math, and the eight seconds you lose from the restart was gained at the original start, since it goes from 59:52:00) It's not a perfect method, but because the sound is now in no way connected to the projector, you can use the "Jump To..." to fine tune the synchronization. I've got it to within half a second, which was good enough that NOT everyone wanted refunds.

THE GRIPE:
Why has Sonics NEVER included the ability to adjust the synch, outside of reseting frame count at the beginning. Even with the old DDP system, there were times when the ability to retard or advance the sound manually would have saved many, many shows.

STATUS AND FEEDBACK:
Our next step, apparently, is to sever the connection from the PLC to the DTAC completely, to further isolate where the damn problem is coming from. Because of the nature of the symptoms, it's a "Well, we'll just have to WAIT to see IF it happens again; if it does, call me" kind of problem. Which sucks.

So, any information, speculation, general discussion, etc. you'd like to throw out, go for it!

"I'll give you a topic: the PROJECTOR TIME is neither related to the PROJECTOR, nor in TIME with anything ... discuss."

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Robert Stawiarski
Film Handler

Posts: 62
From: MW
Registered: Aug 2003


 - posted 07-21-2004 07:52 PM      Profile for Robert Stawiarski     Send New Private Message       Edit/Delete Post 
Brian, I wish I could help, but I have not experienced that myself.

Also, only a small handful of posters on here have DTAC experience. Might want to try the 1570.com Technical Issues forum where you will have a much better pool to draw from.

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Gordon McLeod
Film God

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From: Toronto Ontario Canada
Registered: Jun 99


 - posted 07-21-2004 09:54 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
That is when it is good to have the MagnaTec Dubber running in tandem

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Adam Martin
I'm not even gonna point out the irony.

Posts: 3629
From: Dallas, TX
Registered: Nov 2000


 - posted 07-21-2004 10:19 PM      Profile for Adam Martin   Author's Homepage   Email Adam Martin       Edit/Delete Post 
We battled this exact problem in Sacramento for almost A YEAR. Our problems there were also complicated by random audio looping and skipping at no particular time and for no particular reason.

We replaced the Ginseng with the TIC card, replaced (one-by-one) EVERY card in DTAC, replaced the power supply, replaced the hard drives (twice) and finally stopped deleting soundtracks from the drives and stopped defragging.

Replacing the drives (we had the 80gig drives) the second time and no longer deleting soundtracks or defragging seemed to solve the problem. It never came back.

To overcome the obvious issues of not deleting soundtracks and not defragging, every service required deleting every soundtrack file off of the backup drive, unregistering unneeded soundtracks, rebooting, using windows explorer to copy all of the soundtrack files to the blank backup drive, swapping the drives, and repeating the deletion, reboot, and copying process back to the master drive.

Tim Silver is the Imax tech who had to deal with this and he's based in Los Angeles.

quote: Brian Michael Weidemann
Why has Sonics NEVER included the ability to adjust the synch, outside of reseting frame count at the beginning.
Because they fired everyone who knew anything about how DTAC works when no one wanted to move from Alabama to Toronto when Imax purchased the rest of the company.

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Brian Michael Weidemann
Expert cat molester

Posts: 944
From: Costa Mesa, CA United States
Registered: Feb 2004


 - posted 07-21-2004 10:38 PM      Profile for Brian Michael Weidemann   Author's Homepage   Email Brian Michael Weidemann   Send New Private Message       Edit/Delete Post 
quote: Gordon McLeod
That is when it is good to have the MagnaTec Dubber running in tandem
I'm all for that! We just don't have one. And I haven't seen a DTAC/dubber combination in any theatre. It seems once the "reliability" of the DTAC showed up, the dubbers seemed unnecessarily superfluous (an intended redundancy).

Adam, I've worked with Tim before. He's been out for at least one service that I can recall. And I can get his number from my tech, too.

We had the audio looping, skipping, and freezing issues a long time ago, and haven't happened in a little over a year. The first time was when the sound got caught in Lion King, a two-second loop from the chorus of Hakuna Matata ... now that would drive ANYONE nuts!

quote: Adam Martin
Replacing the drives (we had the 80gig drives) the second time and no longer deleting soundtracks or defragging seemed to solve the problem. It never came back.
Interesting. The problem doesn't seem to be related to the hard drives at all, since it's never at the same point in the movie. But if new drives the first time didn't work ... hmmm. I get the impression that you guys never figured it out, it just seemed to stop at some point. It's been a while since we've deleted anything or defragged, but it had happened before the last time we did, too. Hmmm ...

Thanks so much for the info, though!

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Adam Martin
I'm not even gonna point out the irony.

Posts: 3629
From: Dallas, TX
Registered: Nov 2000


 - posted 07-21-2004 11:05 PM      Profile for Adam Martin   Author's Homepage   Email Adam Martin       Edit/Delete Post 
quote: Brian Michael Weidemann
it's never at the same point in the movie
Ours wasn't at the same place in the movie every time, either.

I actually replaced the master drive with another drive of my own (later getting yelled at for trying to fix the problem [Razz] ) and still had the skipping, etc. problems. We could go for days without problems and some days we'd have a show go down 8 or 9 times. Sometimes hitting "Stop" on DTAC and re-starting (re-chasing) would correct the problem and other times, DTAC would entirely lock up.

It's my opinion that us not deleting and not defragging solved the problem, and that DTAC has issues with the 80gig drives (because there are several theaters out there having the same type of problems) but Imax seems to think it was the drives. Despite the fact that I used the third-party drive with the same results. [Shrug]

We documented the problems we were having pretty well and I probably have 50 pages in the log book devoted to DTAC problems. Unfortunately, I'm out of town for the next month and can't get to my copy.

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Bob Brown
Expert Film Handler

Posts: 146
From: Grand Rapids, MI
Registered: Apr 2002


 - posted 07-22-2004 11:23 PM      Profile for Bob Brown   Author's Homepage   Email Bob Brown   Send New Private Message       Edit/Delete Post 
So Adam, are you suggesting that I do not delete and defrag the HD in my DTAC unit?. IMAX installed new 80 gig HD's last December. I have, on the instructions of Norm at IMAX, been defraging the drives on a regular basis. I also have been deleting all old registered files. We have NOT experienced the problems you and Brian have been dealing with, at least not yet! Is this more of a GT problem than SR?, or just one more DTAC issue to be on the look out for.

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Daryl C. W. O'Shea
Film God

Posts: 3977
From: Midland Ontario Canada (where Panavision & IMAX lenses come from)
Registered: Jun 2002


 - posted 07-22-2004 11:35 PM      Profile for Daryl C. W. O'Shea   Author's Homepage   Email Daryl C. W. O'Shea   Send New Private Message       Edit/Delete Post 
Unless you're using some lousy defragmenter there's no logical explanation why you'd have problems with a presumedly less fragmented volume.

However, not deleting things (solving the problem) makes sense assuming there is some sort of indexing system -- that is possibly (probably) getting corrupt, or inaccurate, when things are purged.

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Richard Hamilton
Phenomenal Film Handler

Posts: 1341
From: Evansville, Indiana
Registered: Jan 2000


 - posted 07-23-2004 02:17 AM      Profile for Richard Hamilton   Email Richard Hamilton   Send New Private Message       Edit/Delete Post 
You need to replace all of the equipment with Megasystems 8/70 projectors and sound systems;) We never have any sync problems!!!

Rick

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Adam Martin
I'm not even gonna point out the irony.

Posts: 3629
From: Dallas, TX
Registered: Nov 2000


 - posted 07-25-2004 12:42 AM      Profile for Adam Martin   Author's Homepage   Email Adam Martin       Edit/Delete Post 
The hardware in the GT and SR DTAC systems differ a bit since the SR self-generates timecode and the GT requires an outboard converter.

Now that I think about it, the other theaters that I've talked to that are having the problems described above are all GT theaters.

I would say that if you're not having problems, continue whatever you're currently doing.

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Brian Michael Weidemann
Expert cat molester

Posts: 944
From: Costa Mesa, CA United States
Registered: Feb 2004


 - posted 07-25-2004 01:02 AM      Profile for Brian Michael Weidemann   Author's Homepage   Email Brian Michael Weidemann   Send New Private Message       Edit/Delete Post 
Oh, now really, what good will that advice do?! [Wink] I say if you're not having problems, do EVERYTHING different that you possibly can, until you DO have problems. That way you know exactly what NOT to do in the future. Simple. [Razz]

As a kind of update to our problem, my tech suggested I go back through the log to pinpoint when our specific reset problem started happening with when they connected the theatre's fire alarm to the E-Shut. (Parenthetical "off the record" comment edited out.) The fire alarm was connected a month before the first reset. The suggestion is that there is crosstalk, or some ungrounded pulse that's sneaking over to the frame count area from the theatre's fire alarm network, since it's been connected ever since the fire inspection.

It sounds fairly unlikely, but we'll see if anything happens. At this point, I'm willing to accept that the lost Mars probe really hit our building and is sending out interference which is causing this. In fact, that could explain a whole slew of random crap ... our auditorium wall lighting going out all the time, for instance. Or the ushers tending not to clean for the last show of the night. Makes sense.

[ 07-26-2004, 08:09 AM: Message edited by: Brian Michael Weidemann ]

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Adam Martin
I'm not even gonna point out the irony.

Posts: 3629
From: Dallas, TX
Registered: Nov 2000


 - posted 07-25-2004 10:16 AM      Profile for Adam Martin   Author's Homepage   Email Adam Martin       Edit/Delete Post 
Our fire alarm was not connected while we were having the problems. Hmmm ... and neither was the network connection, but the phone line might have been.

quote: Gordon McLeod
That is when it is good to have the MagnaTec Dubber running in tandem
Unfortunately, you can't put a 150-minute reel on the dubber. (Unless, maybe, you concoct some sort of reel transport out of a tower or something.)

quote: Daryl C. W. O'Shea
Unless you're using some lousy defragmenter
Diskeeper running under WinNT 4 is what's installed. And there's apparently no way to upgrade the OS and still have the hard/software work. [Roll Eyes]

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Gordon McLeod
Film God

Posts: 9390
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 07-25-2004 12:21 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
"quote: Gordon McLeod

That is when it is good to have the MagnaTec Dubber running in tandem

Unfortunately, you can't put a 150-minute reel on the dubber. (Unless, maybe, you concoct some sort of reel transport out of a tower or something.)"
When Fanasia came out I visited one theatre that had an Eprad Wall Mut beside their dubber for just that purepose

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Daryl C. W. O'Shea
Film God

Posts: 3977
From: Midland Ontario Canada (where Panavision & IMAX lenses come from)
Registered: Jun 2002


 - posted 07-25-2004 09:21 PM      Profile for Daryl C. W. O'Shea   Author's Homepage   Email Daryl C. W. O'Shea   Send New Private Message       Edit/Delete Post 
So long as it's NT4 SP6a it should be a very solid system. Knowing that it's Diskeeper, I would be confident in ruling out defraging as a part of the problem. It's far more likely an indexing problem.

Is the timecode generator well grounded? Is it on a power conditioner, or at least a good, not cheap, UPS?

Is there a way to monitor the timecode coming out of the TC generator before it hits the DTAC?

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Gordon McLeod
Film God

Posts: 9390
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 07-25-2004 09:47 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
Use a DTS and JSK generator off the tach and all the problesm will go away [Smile]

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