Film-Tech Forum ARCHIVE: DTS automation switching question

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Posted by Aldo Baez (Member # 790) on 02-10-2002, 02:17 PM:

Ok bear with me because I'm still trying to learn alot of the stuff in the booth technically (Only been a projectionist 3 years.)

We have a house that has a Dolby basement reader for its digital sound. This basement reader has *always* given us problems, always 6,F,6,F,6,F, and always switching back and forth from SR, to SRD making the auditorium sound really bad in the process. Considering our technician is not very good (We've had some platters broken for a year, and I don't have the expertise to fix them), I have to find some sort of workaround for this Digital problem. This house also has an installed DTS system, and we have a cart that roams around and we could place on different projectors, so I decided to put it in the projector that has the digital problem. That took care of the problem, you can run the movie in DTS and it sounds great, BUT I'm trying to figure out a way to make the automation automatically switch to DTS when the feature start cue runs through. The only way DTS will run is if you manually press the external channel button to switch it to DTS. The projector is set to go to Dolby Digital instead of DTS. My projectionist are lazy and always forget to switch it to DTS, and I'm never there to babysit them all the time so I can't do a thing about it.

We have a CP500, with an all christie setup, and I've looked through the the DTS manual and there is nothing there, so I looked through the CP500 manual and finally found something that might do it. You can assign Sources and Targets to the CP500 as to what it will switch to when the cue goes through and you have it set on auto-digital. Right now the sources are Mono, A-Type, SR, and the Target is Dolby Digital, which it does switch to when the feature start cue runs through. I tried putting the external channel as a source, but that did not work because it switched to DTS for the trailers when a trailer was on, but did not switch out when another trailer came on that was not on the DTS trailer disc. So I tried putting external channel as the target to switch to when the cue went through and that did not work either as it stayed on external channel even when our policy went through which isn't DTS. So, my predicament is how do I put it so when the feature start cue goes through, it will switch to DTS and NOT Dolby Digital. The wierd thing is is that we have CP65's in our smaller houses that do this flawlessly (although they don't have basement readers) so I'm pretty sure it can be done.

Posted by Brad Miller (Member # 2) on 02-10-2002, 02:25 PM:

Explain the wiring between the dts unit and the CP500 in the back of the sound rack. Is there a wire coming from the "automation" connector of the dts unit to the CP500? Also, is this a 3 drawer dts unit?

Posted by Rick Long Jr (Member # 541) on 02-10-2002, 10:40 PM:

The auto digital functions on a CP-500 ONLY work with SR-D (Dolby Digital) and will not work with DTS. The system was intended to switch to SR-D only when the processor is currently in a film format. Which is why 01, 04, and 05, are assigned as scource formats (the little 's' indicates this) and format 10 is the target (indicated by the little 'a') if you assign format 11 (external) you could end up with NO sound. The system switches only when valid DOLBY Digital data is read, therefore if no DTS is being read and you had format 11 as a target, guess what would happen.
DTS is designed to pulse the processor to format 11 as soon as timecode is read irregardless of what format the unit is currently in.
If the DTS system is portable, what kind of interface is used between the automation connector on the back of the DTS unit and the CP500. The interface card used for this in permanent mount situations is the D-715 and is usually found on the back of the CP500,but may noy be there if its a homemade interface.
As for the problem with your SR-D reader. If your reading 6F6F it could be an instability issue with the sound drum. Higher readings, like 7 or 8F could be alignment. I'm not very familiar with Christie machines as we don't have many up here (something I've become thankfull for as I learn more about them), but as a start, you could check for a loose or rubbing flywheel on the sounddrum shaft, or it could be something as simple as crud on one of the soundhead rollers.
Try cleaning the soundhead optics as well.

Posted by Karen Hultgren (Member # 395) on 02-11-2002, 11:59 AM:

Aldo,

When conencting the DTS to CP500, you must use the D715 logic interface board to steer the pulses from the DTS to the CP500. DTS sends one pulse when it's in digital and then another one when it drops out. If it drops out during the feature, it will drop to 04 or 05, if at the end of the feature, it will drop to nonsync.

I suggest you get a DTS setup disc and test the setup.

You don't have to add any sound cues to pulse the CP for DTS. But if you must use cues, remember to never put any cues on film that has timecode, it will over-ride the DTS pulse. Put all sound cues on black leader before timecode starts.

For DTS - CP500, we normally appear on Format 11 (external).

I hope this helps. If you have more questions. Please send me an email.

Karen at DTS
khultgren@dtsonline.com

Posted by Aldo Baez (Member # 790) on 02-12-2002, 02:49 PM:

<As for the problem with your SR-D reader. If your reading 6F6F it could be an instability issue with the sound drum. Higher readings, like 7 or 8F could be alignment. I'm not very familiar with Christie machines as we don't have many up here (something I've become thankfull for as I learn more about them), but as a start, you could check for a loose or rubbing flywheel on the sounddrum shaft, or it could be something as simple as crud on one of the soundhead rollers.
Try cleaning the soundhead optics as well. >

Believe me, I've tried *everything* to try and get it to read digital, thing is we have 5 exact same houses, and two of them are like this, the other three run perfect every single time.

Brad as for the connection of the DTS, I know there is an automation cable connected to the DTS unit, and it is a 3-disc drive. I will try and take some pictures of it because I cannot remember all the technical names yet, but what I'm thinking is that when the cue goes through it signals the processor to go to auto-digital but the film is still a non-digital soundtrack (such as the 8 foot black leader on black hawk down) so it stays on SR until digital comes, by that time there is no pulse or anything from DTS, and Dolby Digital read is bad.
This explains the fact that I forgot to mention earlier that sometimes it kicks into DTS perfectly, but most of the time it doesn't.
And Karen our feature start cue goes on the middle of the film on our feature presentation policy so I don't think that is ever a problem.

Thanks !

Posted by Brad Miller (Member # 2) on 02-12-2002, 03:57 PM:

Is "external digital" programmed into SK5 (the upper right button)?

The "automation cable" should be a 25 pin cable that goes from the dts into a small green breakout board, which plugs into the bottom left corner of your CP500 (as viewed from the rear).

Turn off your "auto digital" crap on the CP500. Make sure there are no "targets" or "sources". Since your SRD doesn't work properly, my initial guess (assuming things are wired correctly) is that the faulty SRD is trying to force it into SK4 (Dolby Digital), but it keeps defaulting to SK3 (SR) and prevents the dts from playing. If not that, your "feature cue" might be placed on your prints AFTER the dts unit has started up, which would be a mistake and would also prevent the dts unit from playing.

Posted by Rick Long Jr (Member # 541) on 02-12-2002, 10:44 PM:

>Believe me, I've tried *everything* to try and get it to read digital<
Have you checked the exciter amplitude across the C.C.D. with a 'scope? If its too low, the error rate can be high even when the DRAS 10 tells you everything else is O.K. I have found that exciter position or illumination are the most likely culprits affecting SR-D systems that worked at one time.

Posted by Roy Claflin (Member # 1113) on 02-13-2002, 12:42 AM:

We had a similar problem in one our DTS houses.

Some prints would switch to DTS for the attached trailer, then switch back to SR as the feature start cue ran through. It was confusing, considering that none of our other DTS houses did this. So, what I did was I moved the placement of the cue ahead, until it would pass through the failsafe about a half-second before the tiny break in the timecode between the feature and the trailer. This solved the problem. If there was no break in the timecode (Rollerball was like that), I put the cue on before the attached trailer. It does mean the house lights go down a bit early, but like Aldo, I too work with lazy projectionists. Try it out; see if it works.

Posted by Tim Turner (Member # 1109) on 02-13-2002, 12:34 PM:

This "basement reader". I was told it was called a thermostat. Is this another name for it?

Posted by Karen Hultgren (Member # 395) on 02-14-2002, 06:03 PM:

Aldo,

Test the DTS system with a setup disc. If it the CP500 is automatically pulsed into external (for DTS) and then, when the disc is ejected the CP500 goes to optical, then the DTS is working correctly and something external is overriding our pluses.

CP500 factory units come setup for External to appear on SK5. That is where we normally send the DTS pulse.

I hope that helps.

Karen at DTS
khultgren@dtsonline.com

Posted by Aldo Baez (Member # 790) on 02-18-2002, 07:32 PM:

Brad, I tried your idea of turning off all the sources and targets and that did not work either. The feature start cue would go through, I place it at the very end of our feature presentation trailer (right before the feature film), but it would kick back to Dolby SR. Here are some pictures of the unit:

Where the unit plugs into.

The unit itself (yes I've dusted it you can't even see that in the dark! hehe)

The back into the CP500, the thick white cord you see on the left is from the dts unit as well as the reader, it connects to that green board.

I've tried not putting a cue, I've tried putting a cue on the actually movie instead of our feature presentation, it doesn't work unless you actually manually put it in. Karen, I started working at this theatre 1 year after it opened and I haven't seen any setup disks. If possible could we be sent one? My email is abaez@mediaone.net for the address.

Thanks alot everyone I will keep trying.

Posted by Gordon McLeod (Member # 33) on 02-18-2002, 07:36 PM:

On the back of the processor momentarily ground the automation terminal for the dts and see if the unit switches
If it does try the same thing on the pins of the cable after disconecting it from the DTS automation If it works there then the cable is good if not then replace the cable
It is probable that something else is overriding the DTS
It is possible that the something is holding the processor in the SR format continously Haveing just looked at the pictures try replace what appears to be a gender bender it is possible not all the pins go through

Posted by Rick Long Jr (Member # 541) on 02-18-2002, 10:23 PM:

The DTS unit momentarily grounds pin 25 on its automation connector when it goes into digital . The D-715 steers this pulse to pin 5 on the back of the Dolby . A Quick test would be to temporarily disconnect the D-715 card from the CP-500 and ground pin 5 for a second. It should switch the Dolby to format 11. Then reconnect the D-715 card and connect the cable that comes from the automation connector on the back of the DTS unit directly to the bottom connector on the D-715 card, bypassing the DPP-10 interface. This unit could be set to look for the digital pulse on another pin.
Anybody got any information on that unit?
Also one question. Does the system default properly? The automation will pulse the Dolby to format 60 at the end of a show, but try Blocking the timecode reader to see if it switches to 05.

Posted by Brad Miller (Member # 2) on 02-18-2002, 10:24 PM:

If you know how to do what Gordon recommended, try those suggestions. If you are not completely clear on what he is saying, do at least go to a computer store and get a proper cable to get rid of that little black "gender changer" that is on the end of your automation cable.

Also, if none of that works, do bypass that roll around plug-in thing and wire the dts automation cable straight from the dts unit to the CP500.

Posted by Karen Hultgren (Member # 395) on 02-19-2002, 01:26 PM:

What is that grey adapter from the DTS white cable to the D715? The DTS cable should plug directly into the D715 board.

Karen at DTS

P.S. Nice photos!

Posted by Gordon McLeod (Member # 33) on 02-19-2002, 03:02 PM:

I think that adapter is there because of teh cable harness from that plugin panel they have on the front of the rack
Go direct and see what happens