Film-Tech Forum ARCHIVE: National Treasure DTS problem

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Posted by Chris Brown (Member # 2800) on 01-07-2005, 12:45 AM:

For the last 3 days or so, I've been having an issue with our National Treasure print, and I was hoping maybe somebody on here more wise than I might have an idea...

Basically what is happening is that about 45 minutes into the film, the DTS stops reading, and the sound switches back to SR. It keeps on switching back and forth until someone comes and powers off the DTS unit, powers it back up, and waits for the discs to sync up with the film again. Otherwise, according to customers, the sound just keeps jumping formats for the remainder of the show.

Now from what I know, I would suspect a problem with the timecode on the film itself. We had no troubles with the print before this (having had it for about 6 weeks now), the discs themselves look fine, and I know the DTS unit is fine because that particular auditorium is sharing with another print, which has had no problems with sound whatsoever.

Anyone have any suggestions? Thanks.

Posted by Darryl Spicer (Member # 711) on 01-07-2005, 10:21 AM:

Verify that the DTS reader on the projector head is giving a steady green light no flashing. There is a 4 second span that the timecode can be missing before the unit switches out of digital. Give us the model of the dts unit. Is it 2 disc 3 disc.

Posted by Chris Brown (Member # 2800) on 01-08-2005, 01:26 AM:

The light on the reader does indeed start flashing...which would support the idea that the problem is with the timecode. Oddly enough, we had this exact problem with a Harry Potter print over the summer, in the same auditorium. Probably just coincidence I'm sure.

Anyways I dont recall the model number on the DTS unit; it has 2 drives though. We've just been running it in SR the last few days (not like most customers will notice the difference anyways). I was thinking of swapping the print with another auditorium, seeing if it does the same thing, just to verify that its not the reader or DTS unit. But assuming the problem is with the print itself, is there really anything else that can be done, short of replacing the reel?

Posted by Darryl Spicer (Member # 711) on 01-08-2005, 01:36 PM:

one possable problem that I have had in the past is the age of the LED on the reader. The voltage may need to be increased to compensate the age of the reader. If this does not help things the reader may need to be replaced. Sometimes just a slightly misaligned or badly produced timecode can be effected by this. The timecode may play through better with less loss of signal on an increased voltage of LED or new reader.

Posted by Bruce Hansen (Member # 281) on 01-09-2005, 07:06 PM:

Check the print to see if there is any damage to the DTS time code area. You can also try cleaning the LED and the lens. You might also want check the reader gain adjustment (you are adjusting the gain of an op amp, not the LED voltage, you can follow the traces on the board if you wish to prove this).

Posted by Stephen Frazza (Member # 2320) on 01-10-2005, 01:04 AM:

Ive had prints fall in and out like that and it was the voltage to the dts reader led. If you have a multimeter you can try this.

Dts reader led voltage calibration instructions

Posted by Chris Brown (Member # 2800) on 01-10-2005, 02:12 AM:

Thanks for the suggestions guys. When I'm up there tomorrow night I'll give those things a try. Like I said, we had a similar problem in this auditorium over the summer, so it may in fact be a problem with the LED on the reader. The readers are all quite old, and as far as I know, we havent increased their voltages anytime even remotely recently. So we'll see. Thanks again!