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The DTS backup track is the analog track. When there is a problem reproducing the sound the player switch automatically in Dolby SR. This will happen if timecode is lost for more than 4.5 sec, CD rom problem or hardware failure. If your offset switches are bad, the player will see a different offset than what you set but it is not considered a fault! I cleaned the switch with a spray contact cleaner. I had the sync changin continuously during a show...
Do the A/B comparison and let us know!

Karen,
I wish add to Michael question: should count the frame when shutter has illuminated the print the first pass or the second?

Bye
Antonio

I expected that there must be a processor fault, because:

* We had run the print on several occasions in other houses, using the 6-ADs, and it was flawless.

* We had reports of similar problems from another site that has a DTS-6.

* The troubleshooting guide from DTS mentioned this 'drift' problem and suggested replacing the timecode board.

So, naturally, if it were a processor fault, I would expect that the faulty one would drift way out of sync with the working one. What really happened?

Both processors drifted out of sync, together! I don't even remotely know how that's possible. I mean, if the timecode is lost for over 4 seconds, the sound will cut out. How can even an intermittent time-code cause the sync to wander, slowly?

The technician who came by yesterday says that he aligned the reader. I asked if he aligned it with an oscilloscope, and he said that, well, the reader is something that either works or it doesn't. Since he was unable to correct the problem, and can't explain it, he now says that we don't know how to lace the projector correctly. That an incorrect upper loop size will cause a constant sync error (not a drift) is logic that seems to have eluded him. That the other three DTS houses work perfectly also doesn't phase him.

Karen, this is a mystery to me - do you have any ideas? We're talking two different processors out-syncing simultaneously!

Are you saying that the SAME print in a different house is ok and on that houses with two different processors has a sync problem?

Strange...

Wait for Karen's reply...

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Antonio, yes, that's what I'm saying. And I'm saying that a processor with no problems at all, when moved to the troubled house, drifts out of sync too.

>Wait for Karen's reply...

That's a given!

Michael:
>You also checked if the unit was still playing dts when the drifting
>occurred?

Absolutely - there was NO analogue sound available. I hooked up ONLY the time-code to the two DTS processors, and monitored their outputs.

>Remember that analogue can also be a little bit out of sync when the
>loop below the intermittent sprocket is very big or very small!

Again, analogue wasn't an issue - it was non-existent.

>If
>you are dealing with a very large audtorium, that can also add to
>the problem. In that case, you cannot check sync while listening to
>the monitor and watching the movie from the booth window because in >the back of the auditorium, the sound will be late.

I agree, but the sound shouldn't drift that far out on the monitor.

Adam Martin:
>Is the timecode cable firmly seated and screwed down in the reader
>and in the DTS unit? Have you tried grounding the reader to the
>projector chassis with the wire provided on the timecode cable? Are
>the timecode cable connectors corroded? Have you tried a different
>timecode cable?

Adam, I made a completely new cable for the test, because I needed to run two processors simultaneously. So the old cable is not a suspect.

Very scientific, your responses were. But a scientist, I am. Already addressed in my test, your concerns have been. Meditate on this, I will.

Damn - I've watched that film a couple times too many!

Does it always fail in the same place by the same amount? What's the magnitude of the drift, by the way? Are we talking 500ms or 5 seconds, or...?

Have you tried cleaning the optics on the timecode reader?

--jhawk

Brian, do you have another reader? If so, try to swap the "faulty" one and see if the problem disappear.

More: does the "Timecode" green led on the DTS6 is blinking all the time or is it steady?

Let us know!

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What I'd need to know is the data format of the time-code. Anyone know this? Is it standard SMPTE?

Answer to your question: I don't know if it always fails in the same place, because it doesn't always fail. But when it does, goes up to more than 500ms.

Antonio: I would have swapped readers, but the technicians have bolted a film roller to the top of the reader. This won't suit any of our other projectors, because the reader in this cinema is uniquely on top of both the Dolby and SDDS readers. The LED does flash on occasion, and the sound does drop out, despite the tech-head assuring me that he'd adjusted it.

Gordon: The problem is [b]not[/i] likely to be an intermittent time-code board, because it affected both the DTS-6D, and DTS-6AD equally. Unless there is a board in the reader to which you're referring.

Thanks for the useful responses. I await Karen's response.

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So I would say that if your reader has big problems perhaps you can reach also sync problem...

Before aligning the reader be sure that the reader itself is aligned with the projector and with film path. I would not recommend to correct the alignment of the reader/projector (physically) with the lateral screw, use that to correct the alignment of the reader.