Film-Tech Forum ARCHIVE: DTS Dropout on older Acetate

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Posted by Bernie Anderson Jr (Member # 410) on 05-05-2010, 01:23 PM:

I'm using a DTS 6D player and Im getting drop outs of the time code on older acetate prints from the 90's . There is very slight warpage to the film from shrinkage, but other than that the prints are mint. This has happened now on two different reels. On Polyester magenta prints, its absolutely perfect. Any thoughts on how to get it to work right with the older prints?

Thanks

Bernie

Posted by Markus Lemm (Member # 3456) on 05-05-2010, 03:27 PM:

I had a similar issue on an print of Jurassic Park that I ran about a year ago. There is an adjustment on the reader that moves the film in and out to better position the dts track. It is usually under a sticker that says something like "Warning do not adjust". I found that on my print about a half a turn clockwise gave a solid green light.
Just remember to mark were the adjustment screw was so you can move it back.

Posted by Bernie Anderson Jr (Member # 410) on 05-05-2010, 03:33 PM:

I thought that was a no-no? I was also figuring that there maybe a voltage adjustment. If you hook an Oscope up to it, can you see the code?

Thanks

Posted by John Wilson (Member # 269) on 05-05-2010, 04:46 PM:

DTS say it's a factory-set adjustment, but it has gotten me out of a few jams. Just remember to put it back where you found it...and don't let your co-workers know it's an option.

Posted by Bernie Anderson Jr (Member # 410) on 05-05-2010, 04:49 PM:

So it is literally a lateral adjustment just like an analog sound head then. If you go clockwise, you'll pull the big roller in, and counter, goes out?

Posted by John Hawkinson (Member # 1135) on 05-05-2010, 05:38 PM:

Yes. NOTE WELL: there is a setscrew that comes up from the bottom, vertically. Loosen it before you turn the adjustment screw under the sticker.

I may have mentioned this in another thread, but I find the best way to do this alignment on older prints is to patch the timecode signal into the booth monitor and then turn the screw for maximum volume.

I also let my mad instrumentation fetish get out of hand and we mounted dial indicators on the back of our timecode readers, so we can set them right back where they were. But the thread of the adjustment screw is fine enough that this is really just precision masturbation -- marking it with some tape and a sharpie is more than adequate.

--jhawk

Posted by Bernie Anderson Jr (Member # 410) on 05-05-2010, 06:36 PM:

Thanks John,

How do you make the timecode into an audio signal? I get the concept, sounds similar to focusing Pink Noise on analog. Obviously, the louder the audio, the better it reads. Pretty cool.

Thanks

Bernie

Posted by John Hawkinson (Member # 1135) on 05-05-2010, 06:54 PM:

Well, the timecode is a 5V signal, and that's close enough to line-level that you can just directly patch it into an audio amplifier (start with the volume turned down low if you're worried). You have to break out the signal and ground pin from the timecode cable, of course. We have a patch panel in our rack so this is easy to do "live" without disconnecting it from the DTS processor.

I should add, we have DFS's print #958 of Men in Black this week (one of the better prints, I'm told), and R2 seems to have this shrunken problem, so we did this adjustment earlier this week. [Smile]

[I'm 75% sure this is a polyester print, but even old polyester prints can show DTS lateral shifts over time. It does keep shrinking when you're talking about decades...]

--jhawk

Posted by Bernie Anderson Jr (Member # 410) on 05-05-2010, 07:17 PM:

Excellent! I'll have to try it. This is that you do on the fly?

Bernie

Posted by John Hawkinson (Member # 1135) on 05-05-2010, 07:19 PM:

Yes, we do it on the fly. T-ing the signal off to an amp does not appear to have any impact on the DTS processor's ability to reliably decode the signal.

--jhawk

Posted by Bernie Anderson Jr (Member # 410) on 05-05-2010, 08:14 PM:

Can I use any kind of Serial Splitter to tap into the signal instead of going into the plug end itself? Also, since I'm trying to run this with changeovers, eventually, can I use a standard y cable to connect the two projector cables to the DTS player?

Posted by Tony Bandiera Jr (Member # 2365) on 05-05-2010, 09:02 PM:

I think a serial breakout will work just fine to monitor the timecode as most are simply passive terminal-access devices. An active one (with LED's in it) would not work and could damage the reader or TC board.

DO NOT use a serial cable of ANY kind for DTS timecode readers!! Most have too small of conductors to carry the LED current. I found this out the hard way experimenting on my own projector.

And the "Y" cable for two-projector set ups is NOT a "pin-for-pin" cable...look in the DTS manuals to see how it is wired and you will see that a simple "Y" cable WILL NOT work. (Proj 1 and proj 2 use different pins on the 9-pin player end for the timecode, all other functions like LED power, ground, etc. use the same pins on all ends though. )

Posted by John Hawkinson (Member # 1135) on 05-05-2010, 11:21 PM:

Yeah, as Tony said, you should be fine with a serial breakout device. I don't think LEDs are going to hurt anything, the worst that might happen is you burn out the LED with the timecode LED driver current...

They make "standard serial Y cables"? Who knew?! I didn't. But certainly the DTS cable is not a pin-for-pin straight through Y. And for that reason, if you make a DTS-to-audio adapter cable (or DTS-to-BNC Y splitter like they show in the manual), in a changeover setup, you have to use it on the TCR end of the Y cable, otherwise you'll only get Projector #1, since the Y cable swaps the Proj#1 and Proj#2 timecode inputs at the reader end, so both readers can be identical.

Quite possibly this is all too much effort -- you can just twist the adjustment until you get a solid green light on the timecode feedback green LED on the timecode reader...

--jhawk

Posted by Monte L Fullmer (Member # 2797) on 05-06-2010, 03:06 AM:

I've broke that rule many-a-times by tweaking the setscrew on the scanner drum of the readers to get a solid green LED light.

Figured that "it's my booth and my show, so I do what is needed.."

-monte

Posted by Bernie Anderson Jr (Member # 410) on 05-06-2010, 02:01 PM:

On some of my DTS readers at work, there is a wire coming out of the serial plug and is tied back with some shrink tube. What is that for?

__________
Nevermind, I found what it is.

Posted by Gordon McLeod (Member # 33) on 05-07-2010, 12:37 AM:

Even though it is a DB9 connector it is not a serrial connection
per se
some older prints were less than accurate on track placement and the newer readers (the ones with the label on them) had a wider slit to allow for placement errors

Posted by Bernie Anderson Jr (Member # 410) on 05-07-2010, 03:43 PM:

I just replaced the original reader (from 1995) with a newer one (from 2003). Night and day difference. Now that's not to say that a brighter LED didn't help. But it played through just fine.

Bernie